Programme description LISA

Module BASIC Version 4.3

Update: 01.05.2005 Author: Dr. Dr.-Ing. Wilfried Linder, Bad Pyrmont Hagen, Germany Contact: info@maptec.de

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Please read before starting the programme: This programme was carefully developed and intensively tested. Nevertheless, due to the complexity of such software it cannot be excluded that errors were not detected during the programming and testing. Such errors may occur for instance when seldom sequences or combinations of commands are carried out, or if the input data have unusual formats or an extraordinary size. To prevent you as the user from following damages we recommend urgently to control the plausibility of all results given by this programme before any further use of the data. If errors occur, we kindly ask you to inform us about them, if possible together with the corresponding data set. We will do our best to correct the programme as soon as possible, and we will wend you the actualised version free of charge.

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Pre-remarks The programme LISA is divided into two modules: BASIC: Raster GIS software FOTO: Digital Photogrammetry Please take a look at our icon. The little ladybird beetle has got three meanings: it symbolizes luck and shall bring it to you, it refers to a small, highly successful German car, not to a luxury vehicle that is exactly what our software

is about: small, inexpensive but reliable. Please be fair and don't compare beetles with jaguars! in American-English, Kfer (the German word for beetle) means also bug and simultaneously refers to

errors within the program none of the software can claim to be 100% perfect nor can we do. Hardware requirements LISA is developed for the use on standard PCs. Special equipment such as a second monitor etc. is not required. Due to the huge amount of data resulting from raster image processing it is however in your own interest to make sure that there is a high computation speed, enough main and hard disk memory and a good graphics periphery. The necessary and the recommended hardware is shown in the following table: necessary recommended

Processor frequency 400 MB > 1 GHz Main memory 128 MB > 512 MB Available disk space 20 MB > 10 GB Graphics 1024 x 768 pxl. 1280 x 1024 pxl. Monitor 17" 19" In addition, a 3-button mouse and a CD-ROM drive are required. For the input of graphical data a digitising tablet or a scanner might be used, for output printer or plotter. The operating system MS Windows 2000 or XP is recommended. It seems that LISA runs also under different other Windows 32-bit systems (without any guarantee for full functionality!). Installation Very important for Windows NT, 2000 or XP: During system starts, you have to log in with maximum priority (standard: user name = administrator) to have full rights on the system. In other cases the installation will fail with an error message! Installation from CD-ROM Put the CD-ROM into the respective drive. Click onto Start and then Execute. Type for example d:\l_e_setup (according to the CD-ROM drive and the

name of the Setup file) and click onto OK. The next steps are self-explaining - you should use all default values.

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Installation after download from the Internet Create a target directory, e.g. c:\lisa Copy the Setup file (e.g. l_e_setup.exe) into it and start it like a program (double click). The next steps are self-explaining - you should use all default values. Additional settings Now click successively onto Start, Settings, System control, then onto the icon Display and again onto Settings. Control / set the following parameters: Colours: 65536 colours (high colour, 16 bit) or higher. Resolution: At least 1024 x 768 pixels. Fonts: "Small fonts". Now click above onto Representation. Within windows (active or inactive) as well as the dialogue box the following parameters may not be exceeded: Pixel: Size 18 Text: Size 10 In case you have less than 512 Mbytes main memory (RAM) available on your computer, and/or you want to process large raster images a certain part of the hard disk capacity can be made available in addition. Therefore a correspondingly large paging file is to be defined within the Windows system control: successively click Start, Settings, System controls, then onto the icon System and there onto Performance data. In the menu Virtual storage you can define the size of the paging file using the button Modify. For more details, please refer to the Windows manual. In case you want to use a digitiser with LISA, you have to install a WinTab driver which the manufacturer provides with the hardware. Then please install the tablet, switch it on and re-start the computer. Directory structure The following information may fascilitate assessments and provide a general view. After a successful installation, your computer holds directories and files listed below: c:\lisa lisa.exe, foto.exe (programme files) lisa1.fnt, lisa2.fnt (font files) menu.frm (digitiser menu, see appendix) lisa.sys (system parameters) salflibc.dll, freeimage.dll, gidfbib.dll, haspms32.dll (runtime libraries) c:\lisa\text programme description(s), PDF files c:\lisa\common\pal directory for palettes c:\lisa\common\sig directory for area symbols c:\lisa\common\cam directory for camera data

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The internal structure of LISA BASIC Input data: Raster, vector, attribute data Format conversions Digital image processing Digital terrain models Data input with digitiser Format conversions Output: Raster, vector, attribute data Data management, analysis, statistics The data flow in LISA: The kernel of the raster-oriented processing are the modules Digital Image Processing and Digital Terrain Models. The modules for data management, analysis and statistics handle the processed data. General remarks, conventions LISA is project oriented. A project consists of a working directory, co-ordinate range, pixel size and an optional image data base (see option File > Project definition). With the exception of palettes and area symbols, all created files are stored herein and all input files will be searched here, unless the file name is entered with an concrete path. File names may consist of up to 120 characters, if necessary with full path name (e.g. c:\lisa\data\alturas.dat); the standard is to use the working directory indicated in the project. The file extensions (e.g. .IMA) are fixed, cannot be changed and therefore they usually dont have to be entered. Beside others these are: .DAT common ASCII file, e.g. reference point files (*) .DBF attributes (format dBase IV) .FLT filter matrix .IMA raster image in LISA format .LEG raster image legend .PAL colour palette for raster image .PRJ project definition .SIG raster symbol .TXT text file, e.g. for legend (*) free choice for input files.

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Each time the name of an (existing) input file is asked for the button ... can be clicked. A file selection window (file manager) will then be opened. In general: input- and output files should be given different names. Exceptions are indicated. All angular data is given in degrees (circle = 360). Directions are reckoned clockwise from North = 0, therefore East = 90, South = 180 etc. Please note that numerical values require a decimal point instead of a comma (input: 3.14 instead of: 3,14) as customary with EDP. Instead of the button OK offered in each input window the enter key may be used. Instead of the Cancel or Back button it is possible to use the ESC key. In addition, some popular options can be called up directly with the buttons right in the main window or using a pop-up menu: click anywhere in the main windows using the right mouse button and a menu will be displayed providing the options to start the display of a raster image, a vector graphics, text or attributes. Program system files During your work with LISA different files are created, which serve the control of the system and simplify the data input. Among others these are: LISA.PRO: name of the project last used. LISA____.PRD: name of the files last used (raster, vector, attributes). IMAGE___.PRD: Contains different information about the size of a raster image. It is created after a

vector-raster-transformation. MODEL___.PRD: contains the names of reference points and DTM file, will be created through

interpolation of a digital terrain model (DTM). DEFLT___.PRD: contains different parameters in order to create plotter files (scale, exaggeration, marks). BIKO____.PRD: Parameters for the manual image co-ordinate measurement (LISA FOTO). STEREO__.PRD: the last used stereo model (LISA FOTO). The first file exist only once in the LISA main directory. The others are generated for each project separately so that the particular parameters can be used there. PRD stands for protocol file. Error messages "Error opening input file": File does not exist, at least not in the current or given directory. In most cases the file name or the path is incorrect or the file exists but is defective (has a file size of 0 Byte, for instance). "Error opening output file": Inadmissible drive, inadmissible file name (regard Windows conventions!). "Error reading input file": The file is incomplete or the format is not correct. "Error writing output file": Usually there is not enough storage capacity. "Error reading/writing internally": Mostly refers to defective input data. "First load or interpolate DTM": This operation has to be executed before calculating any kind of DTM resulting products (like contours, ortho images). "Files do not fit together": This message may refer to one or more of the following parameters: No. of image rows and columns, depth of image [bit], co-ordinates of the lower left or the upper right corner, pixel size, concerning a DTM height range.

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"Maximum size exceeded": A raster image is larger than allowed. Remedy e.g.: Reduce the number of rows and/or columns, increase pixel size (within the project definition), reduce exaggeration factor (profile, 3-D view). In general: Before starting the program make sure that there is enough space for the output files on the storage medium (hard disk). Otherwise the program will terminate at some stage giving the message "Error writing output file". WARNING: It may happen that data gets lost! Differences between the test and the full version The performance of the test version which is available as a free download from the internet is compared to the full version limited regarding the following aspects: the maximum image size is limited to 10 MB the maximum number of points (vector data) is limited to 50000 the raster image data base is not available True colour images (24 bit) cannot be processed To upgrade the test version in order to gain full access see the chapter Upgrade to the unlimited full version (below). Help function For this option, the programme Adobe Acrobat Reader must be installed. You can download this from the internet (http://www.adobe.com/). With a click onto the button Help or hit the F1 key, this programme will be started and the programme description loaded. Now activate in the Acrobat Reader the option Bookmarks, giving you a list of the chapters. With this you can easily reach the respective chapter. In case of problems please check first if the respective file (e.g. LISA.PDF) exist in the LISA subdirectory TEXT.

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File

Starting LISA, a project has to be declared. With this, a working directory, an optional image archive, co-ordinate frame (minimum and maximum for x, y and z) and a pixel size will be defined. In the working directory all input files are searched for and all output files are stored by LISA. This way a flexible and clear data arrangement is possible. The project definition files are in the ASCII format, have the extension .PRJ and are located in the program directory (usually c:\lisa). File > Select project Corresponds to a new start of the program. Alternatively, the last used project can be taken, one of the existing projects can be chosen or a new project can be defined (see below). File > Project definition The following parameters has to be defined: Name of the project. From this, the definition file (extension .PRJ) will be generated. Working directory (folder) this can also be chosen from a tree diagram using the respective button. If the

directory doesnt exist it will be created. Image data base (optional, see programme part data base). Already existing data can be loaded into the

working directory using the respective button. Co-ordinate range in x and y as well as the pixel size. The button Reset puts Co-ordinate range to the

maximum possible one. In such a case it is without any meaning! Optional the x and y values can be rounded to an integer manifold of the pixel size.

Co-ordinate range in z. The button Reset puts them to 0 ... 5000 m. A unique value range for z is very important for the generation and matching of DTMs! As an option, a fixed scaling grey value = z value can be selected. DTMs then will have a height resolution of 1 meter.

Length unit (m, mm, m or km). The pixel size and the range of the z-values are invariably fixed for all the data of a project! Therefore these values should definitely be chosen carefully! The co-ordinate limits can also be overtaken from an existing geo-coded raster image or a vector file (buttons Reference raster or Reference vector). File > Edit project After choosing an existing project, its parameters can be modified.

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File > Import vector graphics Input formats: DXF, ASCII- files with any sequence, dBase DBF, MapInfo MIF, ArcInfo E00 ASCII, polar co-ordinates. TASH KOR, SCOP INP, TOPSY KTB, Zeiss PHODIS (several vector DTM formats), LISA old. Output file: Format No., x, y, z; ASCII, extension DAT. Single points are stored with the code 1, lines with the code 5001. Special features: AutoCad DXF (release 11 and higher): All lines up to the entry ENTITIES are skipped. Co-ordinates which follow the entries LINE or POLYLINE (and then VERTEX for several times, until SEQEND) are rated as points on one line. Co-ordinates after VERTEX without previous POLYLINE or after POINT are rated as single points. All other entries will be ignored. Normally, the z value will be adopted directly from the file, but as an option, the layer number may be used instead. In the same way, the layer number can be used as code. ASCII, any sequence: universal import filter for files containing the required entries x, y, z as well as optional the number for each reference point within one line, but in an unusual order or sprinkled in among other pieces of information. Example: In each line the entries point No. code_1 z code_2 x y operator are stored in the course of which the first 6 entries are numerical and the seventh is in textual form. For the processing in LISA, however, the data must look like this: point No. x y z Accordingly, the number of (numerical) entries has to been set to 6, the position of the number to 1, of the x-value to 5, of the y-value to 6 and the one of the z-value to 3. Further more the separating sign between the entries can be provided, e.g. space or semicolon. Before the data is being read the following operations take place internally, first (1) all separating signs are replaced by spaces (mute characters), (2) all commas by full stops and (3) all non-numerical characters by spaces as well. This leads to a slightly slower reading speed with a high tolerance threshold concerning the formats (so e.g. CSV files or others with semicolon, tab stops etc. can be processed without any problems). For a maximum of 15 numerical entries within one line and a maximum line length of 200 characters. Dbase DBF: The input file has to contain each a field for the x and the y co-ordinates. From the remaining fields, one must be chosen from which the z-values are taken. Values for x, y and z are set to 999999. MapInfo MIF/MID: Adopted are entries of the types POINT, LINE, PLINE, PLINE MULTIPLE and REGION. A numeric field of the MID file can be used to give the z values, otherwise the z values will be set to -999999. Arc/Info E00 ASCII: Entries of lines (part ARC) as well as anchor points (parts CNT or LAB) will be adopted. Lines will be given a code according to the so-called coverage-ID (if lower than 5001, increased by 5000). Individual points are given the code 1 and the so-called centroid number from the input file. If DTM grid points are found (part GRD), the output file is closed. The grid points will then be imported into a 16 bit raster image (DTM) by the same name as the output file but with the extension IMA. As an option, an additional 8 bit image may be derived. Polar co-ordinates: For this option, no input file must be defined. Beginning with a starting point, all other cartesian co-ordinates will be calculated using the distance and the direction (= polar co-ordinates) and will be stored in the output file. LISA old: Vector data of older programme versions will be updated, the file name is maintained. The point numbers remain unchanged, the codes are transformed (for instance, 201 5001, 202 5002).

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File > Import raster image Input formats: BMP, JPEG, TIFF each 1 24 bits, single band byte map (RAW) 8 / 16 / 32 bit with or without header, multi band byte map at 8 bit each, IDRISI 8 32 bit, ArcInfo ASCII 8 or 16 bit, GTOPO30 16 bits (DEM), SRTM 16 bits (DEM), From clipboard, LISA old. Output file: LISA raster image, extension IMA. Special features: BMP 1 or 4 bit: is converted to a nominal size of 8 bit. BMP 24 bit: Either one or more colour extracts of 8 bit each (red, green, blue) or one 24 bit image may be generated. A single 8 bit mixed grey value image may be produced in addition. The name of the output files will be added by _R, _G, _B or _M (mixed image). JPEG, TIFF: For import, parts of the FREEIMAGE library are used. Either one or more colour extracts of 8 bit each (red, green, blue) or one 24 bit image maybe generated. A single 8 bit grey value image may be produced in addition. Byte map 8 32 bit: The length of the header in bytes (without header: enter 0) as well as the number of rows, columns and depth of the image must always be provided. If known, the co-ordinates of the lower left corner and the pixel size (for geo-coded images) may be entered. Further more the minimal and maximal terrain elevation (especially for raster DTM) can be provided. In case of 16 bit images which have been generated on machines with Motorola processor the Motorola option should be activated. This causes a reversal of the byte sequence. Subsequently, the grey tone range used in the input image must be selected: 0 ... 32767 (unsigned integer) or -32767 ...32767 (signed integer). Intel-processor data always uses the latter format The option z-value = grey value causes an appropriate equalisation. Multiband byte map: The source has to be a normal (not compressed) byte map file, containing between two and seven bands at 8 bit each. Inside the file they can be arranged in different ways: either point interleaved (BIP; point-wise channel 1 to channel n, each), line interleaved (BIL) or band sequential (BSQ). The output is an 8 bit raster image of each band. The output image name is extended by _R, _G, _B and _M (mixed image). It is also possible to import channel 1 only. IDRISI: Only for files with the extension RST (simple byte maps without header). A documentation file by the same name and with the extension RDC must exist in the same directory as the image file. GTOPO30 DEM: For the import of tiles (normally 6000 rows x 4800 columns) of the world-wide available 16-bit raster DTMs. Beside of the image file (extension DEM) a file of the same name but with the extension HDR (additional information) must exist. Optional, the whole DTM or a part of it can be transformed to one of the projections Gauss-Krueger or UTM. SRTM DEM: For the import of tiles (1 x 1 degrees) of the world-wide available 16-bit raster DTMs. Optional, the DTM can be transformed to one of the projections Gauss-Krueger or UTM. From clipboard: The name of the input image is irrelevant. Either one or more colour extracts of 8 bit each (red, green, blue) or one 24 bit image maybe generated. A single 8-bit grey value mixed image may be produced in addition. Remark: If the header of the input file contains a colour palette (usually when 4 or 8 bits depth), this will be directly used in the header of the IMA file.

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File > Export vector graphics Input file: LISA vector file with the extension DAT. Output formats: AutoCad DXF, Standard ASCII, dBase DBF, MapInfo MIF/MID, ArcInfo E00 ASCII, Excel CSV, HP-GL (plotter), IGES (CAD). Note: In the vector data display, vector data can also be converted into the raster image formats BMP or JPG or transferred into other programmes using the clipboard. Special features: Standard ASCII: The contents of the input file will be exported without point numbers and codes. The delimiter sign (e.g. ";") and the decimal sign (point or comma) can be chosen. Dbase DBF: A DBF-file with three numerical fields (x-value, y-value and z-value) is generated, each of which having 12 digits with 3 decimals; the name of the third field may be altered. This file can be used to generate an attribute file, for instance by replacing z-value field by another and/or adding further fields. (Option Output > Attributes, see below). MapInfo MIF/MID: Apart from the x-y-values the code as well as the z-value is exported. Important notice: If MapInfo is being launched subsequently and a new relation generated based on these files, the original file (from LISA, extension DAT) will be overwritten! Therefore it should be stored in advance. HP-GL: Version 1, for output on a pen plotter. File > Export raster image Input file(s): LISA raster image(s) with the extension IMA. Output formats: BMP, JPEG, TIFF each 1 24 bits, RAW (a simple byte map without a header) 8 or 16 bit each, IDRISI IMG 8, 16 or 24 bits, ArcView ASCII, ArcGIS ASCII, DAT / vector, Icon (ICO). In case of 8-bit images, the grey values can be modified with the options Normal (like in LISA), Negative or Background white (replaces only grey value 0 by 255). Binary images (1 bit) are always exported black on white, DTMs (16 bit) are always exported normal. Special features: BMP, JPG, TIF: When exporting a geo-coded image, an additional file by the same name but with the extension BPW (JGW, TFW; world file) or TAB may be generated. This file contains the images geometrical information (corner co-ordinates, pixel size) required to be adopted by ArcView or MapInfo. RAW: Besides the image file (simple byte map without header) a documentation file by the same name and with the extension INF is generated. In case of exporting a 16 bit DTM, the option Motorola can be activated to reverse the byte sequence described in the raster import section above. IDRISI: The image file (simple byte map without header, extension RST) and a documentation file (extension RDC) having the same name are generated. DAT / vector: The input image must be geo-coded. Output data is issued as the form No., x, y, z in an ASCII file whereas the z-value is derived from the input image (24 bit: band 3). Especially with grid data the output file can reach a large extent! Single point or profile data: The x/y-values must be entered using an ASCII file. To create profile data, it is

necessary to define the intervals (= distances between points). Grid data: Defined by the co-ordinates of the lower left corner as well as the grid width. As an option for

each pixel of the input image a point may be issued (All Points). Please note once again that the output file can become rather large!

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Points of the raster image for which no information is available (grey value = 0), will normally be issued given the minimal z-value (see project definition). In case of individual point or grid data, the output of such points may be suppressed. File > Reset file attributes Reset the attributes of all files in the working directory. This is a useful option for files which were copied from a CD-ROM and which shall be edited. Files like these have always the attribute read only and could not be overwritten therefore.

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Tablet

General information The LISA digitising module is used for the true to scale input of point or line co-ordinates from a map or an aerial photo on the digitising table or tablet. For this purpose the draft will be rectified internally through control points. Moreover, areas, slope inclinations and distances can be determined. Note: the following possibilities can also be used for on-screen-digitising. With the button Periphery can be tested whether a WinTab driver is correct installed. Setup of the digitiser The WinTab-driver which is accompanied has to be installed first. Further on the tablet should be started before you turn on the PC and the cross hair cursor be placed inside the active area. So the operating system can realise the driver and include it in its coming work. In some cases, the parallel operation of tablet and mouse causes problems: The mouse didn't react or the cursor "jumps". Then, switch on the tablet only if you really need it or put the cross hair cursor, if not needed for the moment, besides the tablet. General information to the mode of operation All kind of maps and paper prints of fixed scale can be processed. The degree of the achieved accuracy depends on the digitiser resolution, the scale of the map or picture, the quality of the draft, the adjustment accuracy etc. Before there can be any measurements in the picture or in the map, as a rule the draft must be orientated. In order to do this you have to create a file containing control points, fix the draft on the digitiser and finally measure the control points. Alternatively you may work without orientation. In this case, device co-ordinates will be registered. The orientation data will be stored in a system file (e.g. ORIENT.DAT) as well as in the output file so that they may be taken over from there if the draft was not removed from the digitiser. Tablet > Control point editor Purpose: Create a new resp. edit control point file. This is necessary in order to orient the draft (map or picture). For a maximum of 900 points. Definition: A control point is a point which can be clearly defined in the draft (e.g. corner of a house or property, cross-roads) and whose terrain co-ordinates (x, y) are known to you. With a map, for instance, all corners of the map or grid intersections may serve as control points. For each point you have to enter the point number and the values for x and y. The z value will not be used because the orientation is done two-dimensional. Also, the BLUH parameters are without any meaning in this case. The number of control points needed depends on the transformation method (see below), a maximum of 900 points can be processed there. The co-ordinates have to be given in a rectangular system (e.g. Gauss-Krueger or UTM) and should be well distributed within the area. If the map gives only geographic c-ordinates (longitude, latitude) these values must first be transformed to Gauss-Krueger or UTM (Vector data > Projections).

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Tablet > Orientation Basically the orientation of the draft can be carried out using one of the following three methods: 1. The draft was newly fixed or removed in between: The orientation must be done completely anew. The control point file is to be entered then. After this the control points have to be measured (digitised). 2. The draft has not been removed. Therefore the parameters of the last orientation can be taken over. Go to the menu Orientation, then select the option Parameters of last orientation. Afterwards the lower left and the upper right corner of the desired part or the entire draft are to be digitised. For the orientation an equation system is set up in the computer which enables a clear assignment to either terrain or device co-ordinates. Concrete: With the help of the control point terrain co-ordinates and the corresponding device co-ordinates, the coefficients ai and bi of the equation systems x' = a0+a1x-b1y y' = b0+b1x+a1y (plane similarity transformation) resp. x'= a0+a1x+a2y y'= b0+b1x+b2y (plane affine transformation) resp. x'= a0+a1x+a2y+a3xy y'= b0+b1x+b2y+b3xy (2nd order polynomial type A) resp. x'= a0+a1x+a2y+a3xy+a4x2+a5y2 y'= b0+b1x+b2y+b3xy+b4x2+b5y2 (2nd order polynomial type B) are determined. For the last three the least squares method will be applied in case of over-determination. In the first case 2 points are needed, in the second at least 3, in the third at least 4 and in the fourth at least 6 points. The selection of the type of transformation depends on the number of available control points and on the geometric state of the draft. So, for a topographic map normally the plane affine transformation is OK whilst for aerial photos usually 2nd order polynomials are taken. The control points are to be measured in the indicated order (as located in the file and displayed in the status line). Points which cannot be measured can be skipped with a button greater than 1. If needed after the last measuring , the residuals in each point (remaining error in x and y, in the terrain unit) as well as their standard deviation are shown. If a single value shows a strong deviation from the arithmetical mean with sufficient over-determination (6 ... 900 control points) the transformation should be done without this point. For this use the option (De)activate point: Give in the index of the point, then click on New calculation. The residuals of this point now are set to each -999.999. With a second time giving the index and New calculation, the point can be re-activated. The residuals are stored in the file RESIDU.TXT, the orientation parameters in another file (e.g. ORIENT.DAT). If the draft has not been moved (see above) the orientation from this file may be taken over by LISA later on. Note: If data shall be obtained without orientation of the map or picture, i.e. only as device co-ordinates, all steps mentioned before do not apply. Then go straight to the menu point Register, click "no" when question "Taking over orientation from file?" appears, click "yes" after question "Registration of device co-ordinates?" and continue as usual. Tablet > Digitise Purpose: Measuring and storing (registering) of co-ordinates (points, lines) in the terrain system (unit meters). For a maximum of 2000000 points.

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At this point as a rule the draft must be oriented already. The name of the output file has to be entered. In case it already exists it may be overwritten or new data may be added. First the lower left and the upper right corner of the draft (or the part to be processed) are to be digitised. Then the co-ordinates of single points or points belonging to a line can be digitised. At the beginning of every measuring cycle (single points, line) point number, increment, z-value and code etc. must be entered. Note the following: The input of a z-value is interesting when digitising contour lines for example. Z must not necessarily be a

terrain height; e.g. when digitising a precipitation map, z would e.g. represent the value for the annual rainfall. If the z-value is unknown or irrelevant 0 might be entered instead.

A code between 1 and 5000 represents single points, 5001 ... 9999 polylines. Codes between 3501 and

3600 can be linked with single point symbols (see option Image processing > Area symbols). The parameter code will be further differentiated for later program versions.

The data input is carried out point after point via pressing key 1 of the cross hair cursor. Keys No. 2 to 8 have the following meaning: 2: Snap to node: For this an already digitised point (e.g. on a polyline) is to be caught. Then press key 2. The exact co-ordinates of the already existing point are taken over. Continue as you like, e.g. with key 1 for registration or finish with key 4. 3: Snap to start: Terminates the measurement of a line by registration the current co-ordinates as well as the ones of the initial point (closes a polyline within the code area 5001 9999). Return to input window. 4: End of measurement and return to input window (then start with a new cycle or end). 5: Interrupt line and immediately measure next line (you need not to return to the input window first; the entered values will be kept). Continue with key 1 or 2. 6: Delete last point. This option can be used step by step for all points of the current measuring cycle. 7: Quit; that means leave current cycle without storing. 8: Shift z-value by the step width entered in the window. This is useful for example when digitising contour lines of a fixed equidistance (= step width) successively. The registration format is No., x, y, z (transformed onto the terrain co-ordinate system); the end of a line is entered in the file with -99 -99. -99. -99. Note 1: If you would like to put in data for digital terrain models, please note that the codes are relevant. Contour lines should be digitised with the code 9009 (soft break line). Note 2: After the interruption of the registration process by pressing cursor key 3 or 4 the output file will be closed (= stored) once and then immediately reopened. This means co-ordinates registered up to that point cannot get lost even in case of an abrupt termination of the program caused by reading errors. Note 3: In case the cursor has only 4 keys, a paper menu can be used (see below). Also, you can activate the functions from the tool bar. Note 4: If you have very much data in the draft so that it seems to be good to subdivide the output into several files, it is not the best way to do this in the form of sub areas. Quite better is to subdivide according to the meaning, for example: File 1 contour lines up to 500 meters, file 2 contour lines up to 1000 meters etc., file 3 watershed, file 4 roads etc. With this it will not happen that objects belonging together are splitted into spaghetties.

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Tablet > Measure Note: For the options described below the draft does not have to be orientated. For the options Area / Perimeter, Slopes / distances and Polyline the map scale must be defined (see below). Area / Perimeter: First the map scale is to be entered and the lower left as well as the upper right corner of the draft are to be digitised. Thereafter areas of any shape may be surrounded (Measurement of break points use cursor key 1); after returning to starting point or pressing cursor key 2 the area will be displayed. For each area a minimum of 4 points has to be measured (triangles: double measuring of one point). The area measurement is done with the strip method (named after Gauss). Further more the compactness parameter is displayed (squared value of the perimeter divided by area). The result is issued with suitable units ( m2, acres, km2, resp. m or km) in the terrain model. Results of additional terrain measurements may be added or subtracted. Slopes / distances: Two points are to be digitised and their respective height is to be entered. From the measured co-ordinates and the height values the program calculates the slope inclination in degrees and %, the horizontal and spatial distance between the two points in the terrain unit (meter) as well as the azimuth (angle against grid-north) in degrees and grads. Polyline: All points of a polyline are digitised one after another; the last one is clicked on with cursor key 2. The total length in meters will be shown. Note: If the length of a closed polyline is asked, it is better to use the option Area / Perimeter (see above) where the parameter perimeter gives the searched result. Define scale: For the options Area / Perimeter, Slopes / Distance and Polyline the map scale must be defined if it is not already known from an orientation or the following option. Scale from distance: Starting and ending point of the distance referred to (e.g. scale bar) are to be digitised and their nominal (terrain) distance is to be entered in meters. The scale of the map will then be calculated. Tablet > Test Useful to find the order of the cursor keys, for example, if they are not labelled with numbers but colour coded. Press the keys of the cursor one after the other and notice (write down!) the number displayed. With the help of the individual keys (No. 1-8) you can call different options in the registration mode (see there). Tablet > Menu bar > Define In case the cursor has only 4 keys or you prefer to work with the menu, then one can be fixed on the digitiser (preferable at the edge). For this, print the file MENUE.FRM (delivered with the program) or copy the corresponding page in the appendix (see below), clip the menu and fix it in portrait at the tablet edge but within the active area. Afterwards click at the lower left and upper right menu corner within this option. The usage of the keys 3 to 8 are then available. The position of the menu bar is stored in the file DIGI.SYS in the LISA directory. Tablet > Menu bar > Delete To delete the definition of the menu bar. This is often necessary for example when a new tablet was installed.

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Vector data

Pre remark concerning the terminology: Vector data are stored as simple ASCII files in LISA. Due to that, the termini vector (-data, -files) and ASCII (-data, -files) are often used synonymously. Basic functions Extracts: From the data available in the format No., x, y ,z (as well as code) it is possible to define extracts of each of these parameters. For example, sub areas can be defined by entering a minimal and a maximal x- resp. y-value (co-ordinates window). Each parameter can be stored being multiplied by a factor and/or increased by a summand (constant). The data outside the extract will not be taken over into the output file. A logical AND-connection follows (if point number in the given range AND x-value in the given range AND y-value ...) as well as a conversion of the form output value = input value x factor + summand. Factor, summand: Here the same applies as described above, but the data outside the limits will be taken over into the output file unchanged. In addition the option Centralize is available for the parameters x, y and z. This allows the corresponding values to be grouped symmetrical around the zero position. Values possibly defined for factor or summand are not taken into account. Points polylines: If for example a reference point file based on digitised contour lines is available for the generation of a DTM, the points belonging to each contour line should be marked "soft break line", which means they have the code 9009; they should further more be marked "end of line marking" -99 -99. -99. -99. If this is not the case, which means all points at hand are single points (code in the range from 1-5000) with the help of this option they can be joined together. For this step the criteria are: Successive points must have the same code, their distance to one another may not exceed a certain threshold. Point numbers and code for the polylines in the output file have to be defined. Data reduction (tolerance): For the purpose of thinning polylines as e.g. digitised contour-lines using the tunnelling method. A tolerance value has to be provided. Two successive points determine a straight line. All successive points which fall short of the defined tolerance value wont be taken over into the output file. Data reduction (grid): As an alternative to the option before, the particular point co-ordinates will be rounded to the given grid width. The larger this value, the more points will be located in the same grid mesh, but only one of them will be used. Match files: For a maximum of 5 LISA vector files (ASCII). If available the header of the first file will be taken over. Define symbols > Points Single points of the codes 3501 ... 3600 can be connected with vector symbols. There are 10 standard symbols (circle, cross etc.) which can be modified in size and colour. A file named VEC_SYMB.DAT will be created in the actual working directory. The size units are. The colour is given via the defined colour value and the corresponding entry in the palette.

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Define symbols > Lines In a similar form like described before, also lines of the codes 8501 ... 8600 can be modified. There are the types continuous, long dashed, short dashed, dotted and dashed-dotted. A file named LIN_SYMB.DAT will be created in the actual working directory. The colour is given via the colour value and the palette like before. Projections This option is for the transformation of ASCII vector data between several co-ordinate systems. For example, non-cartesian geographic co-ordinates (longitude, latitude) can be transformed to cartesian (metric) systems like Gauss-Krueger or UTM. Projections: Geographical Gauss-Krueger Gauss-Krueger geographical Geographical UTM UTM geographical Degree / minute / second Decimal degrees Decimal degrees Degree / minute / second Gauss-Krueger co-ordinates refer to the ellipsoid from Bessel (1841), UTM co-ordinates to the ellipsoid from Hayford (1909). When entering the co-ordinates consider the following: In all cases: If you like to read the input data from file, remember the LISA vector format. In each line there must exist three entries (x, y, z) with z can be set to zero. Geographical co-ordinates have to be entered in the order longitude, latitude and in the unit decimal degree or degree/minute/second as one number (example: 7 degrees 12 minutes 24 seconds is entered as 71224). Besides: eastern longitude positive values, western longitude negative values. Northern hemisphere positive latitudes, southern hemisphere negative latitudes or option Southern hemisphere activated. For the entering of zones: this may be given explicitly in case for example co-ordinates of another than the actual position in question shall be calculated. Otherwise the zone is calculated automatically (from the longitude value). Gauss-Krueger and UTM data have to be entered in the order Easting, Northing resp. East, North and in the unit meter. For UTM besides the zone is to be defined geographically. The Northing values of UTM co-ordinates of the southern hemisphere are according to definition to be entered with an addition value of 10000 km and option Southern hemisphere activated or as negative numbers. If an area is located both north and south of the equator, either all north values should be increased by 10000 km and the option Southern hemisphere activated or values south of the equator must be negative (example: Ecuador). For special applications, the position of the co-ordinate centre in degrees as well as the corresponding co-ordinates in meters can be defined explicitly (Example Colombia: GK system with the centre in the observatory of Bogot, or Austria: GK system with central meridians numbered from the island of Ferro). Further an ellipsoid can be selected. When the data entry is done manually and the points position is located within Germany, the map sheet numbers of the official topographic maps TK25 and TK50 are shown. This may help you to find the actual map more faster.

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Rectification Via a control point file created in the vector graphics display (options Edit > Digitise > Prepare rectification) the input file can be rectified / transformed using the methods described in the image processing part. The control point file mentioned contains the entries No., x_new, y_new, x_old, y_old for each point. Vector Raster The vector data must exist in the form (No.), x, y, z, (for each point one row). The vector- raster conversion may be achieved by creating a new raster image or by entering the data in an existing raster image. All needed data (number of image rows and columns, co-ordinates of the lower left corner, pixel size) can be determined in different ways: Like given raster image (in order to adapt the size to the available image) From project definition No given data (starts range calculation) Like raster image: Suggests the last used raster image. This option can then be chosen in case the vector data should overlay an already existing image or serve as a definition of free cut areas (see below). The raster image has to be defined. From project definition: From the parameters co-ordinate range in x and y and the pixel size given in the project definition, the image size (number of rows and columns) are derived. Range calculation: The border limits of x and y will be calculated, the values of pixel size and height range taken from the project definition. The resulting amount of rows and columns will be displayed for control purposes. After defining the image dimensions the following options can be chosen: Binary raster image. The vector data are entered with definable fixed grey value (e.g. 255 = white), grey value = (rounded) z-value or the height interval given in the project definition scaled to 1 ... 255 (situation overview, scatterplot). Single points can be entered as scare marks and left to your choice also with their point numbers or height values. It is possible to assign symbols to single points carrying codes between 3501 and 3600. These are to be designed with the symbol editor (see option Image processing > Area filling). Area filling using attributes. Precondition besides a vector file containing the geometry in the shape of one or more polygons (closed polylines, code 5001 - 9999) is an attribute file (DBF) with anchor points (maximum one point each polygon). Choose a numerical field out of these attribute files. The value range can be joined to classes (intervals) using one of the following methods: Equal distances with giver number of classes. Equal distances with given width of classes. Equally distributed. According to natural breaks. The size of the interval which shall be interpreted as a break can be defined

using the parameter class width. User defined by a border value file, containing in each row the data from_z to_z grey_value. The default values for number and width of classes shown in the input window are calculated using the well-known formula from STURGES (1926). Example for a file with border values: 12.8 20.7 6 20.7 28.4 7 The values between 12.8 and 20.7 will be given the value 6, those between 20.7 and 28.4 the value 7. The parameter to_z is inclusive, so in the example above a value of 20.7 would belong to the first class (6). Then the

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program fills the polygons with the colour value defined by the class number. The parameter to_z may be dropped in the table. Then it will equal from_z. Example:

20. 6 21. 7

Meaning: 20 will be given the value 6 and 21 the value 7. In the special case that all z values are integers in the range between 0 and 255, instead of a classification the option Class = z value can be used. For the colour representation increasing or decreasing palettes in red, green or blue are available. Note: It is important that the single areas are bordered by closed polylines. Especially these have not only to be closed optically but mathematically as well! In order to meet this precondition, for example you can use the option File > LISA-Files > Display vector data (see there) and then Edit > Move, or when digitising, the cursor button 2 (Snap to node). For the area filling, grey or colour values between 2 and 254 are used; the values 0 (transparent), 1 (black) and 255 (white) cannot be used here. Creating anchor-point-file: For each area (bordered by polygons) an anchor point (point situated within the area) is defined. The anchor-points are stored as ASCII-file with the values No., x, y, area contents. This can then be used for creating an attribute data base with the help of the option File > Export vector > DBase DBF. Vector overlay (a geo-coded image must exist): The vector data are entered into it with the chosen grey value. Similar to binary raster images (see above) the same applies to creating point numbers, heights or symbols. Free cut areas: If the input file consists of one or more closed polygons (code 5001 or higher) and of one or more starting points for deletion (code 4007), only the marked areas for not free cutting of the input image will be taken over into the output image (mask function; compare to this free cut areas with the interpolation of digital terrain models). Note: The option Display > Vector offers more possibilities of editing (see there).

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Image processing

This module is used to create and process (digital) raster images radiometrically or geometrically. These may be obtained in a number of ways, for example: Scanning of paper drafts e.g. with a flat bed scanner Digitising of video images with the help of so-called frame grabbers Photos from digital cameras Taking over from other (graphics) programs Download from the internet As stated before the LISA programs operate internally with their own file format (IMA). With the help of the option File > Import raster some formats can be taken over, especially raw data (so-called byte maps) and BMP files. Thus you should make sure that e.g. when scanning paper drafts (e.g. a map or an aerial) the data are stored in a supported format (usually BMP). Consult the description of the above mentioned module for the possibility of the taking over data from the clipboard. Image processing > Image radiometry Modules which can change the colour resp. grey tone reproduction of an image, e.g. to give it a better contrast or to emphasise certain parts of the image in favour of others, belong to this group. One principle may be pointed out: the information in the original image is the most valuable. Any processing, for instance a filtering, may possibly result in a better optical impression or in an improved possibility for a visual interpretation, but it will never increase the actual information! The image geometry (number of rows and columns, pixel size etc.) remains unchanged in radiometric operations. Note: Because of the grey value changing effects of radiometric operations these shall be used with care in any cases where other calculations concerning the grey values shall follow. For example, land-use classifications shall be done at all times with the original data. Image processing > Image radiometry > Histogram Calculate histogram: A histogram (image of frequency of the individual grey values inclusively sum curve) is calculated and stored as a raster image. Stretch histogram: Improves the contrast by linear stretching. Grey values within a least frequency (e.g. < 0.1 %) or given border values will be transformed linearly onto the defined standard range. The background will be set to 0 or to the given minimum value. Hereby the conversion can also be stored as a table and so be used in the same way for further images (see below, option Conversion according to table). Histogram equalisation: Improves the contrast by creating a standard distribution of grey values. The conversion can be stored as a table and thus be applied to further images of the same kind (cf. below, option "Conversion with table"). Characteristic sign: The sum curve equals the first main diagonal. Two-dimensional histogram: Conveys an idea of the degree of correlation of two images of the same size (channels, 8 bit each). The histogram is created as a raster image whereas the brightness of the grey values corresponds with the frequency. The highest frequencies (bright areas) can usually be found around the main

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diagonal. The more culminated and precise they are the stronger is the correlation between the two channels. A further indication gives the correlation coefficient shown in the lower part of the histogram. Correction of brightness: For images showing an irregular brightness in reference to the illumination. For this regional brightness are calculated. A surface polynomial of second order will then be laid over these values and serves as correction (8bit). Image processing > Image radiometry > Calculation Steps (equidensities): Joins the grey values to groups. In the original 8-bit image there is a maximum of 256 grey steps (value range 0 ... 255) of which e.g. 16 steps (as in a 4-bit image) can be generated. The step interval in grey values is to be entered, e.g. 10: The grey values from 0 - 9, 10 - 19 etc. are joined together. Parts (from ... to): The grey values situated outside are set to the value 0. In case of the grey values have a numerical meaning, the interval can also be defined via the corresponding z values. For example 50, 150: All pixels with a grey value under 50 or over 150 are set to the value 0. If on the other hand only the values below 20 and above 200 shall remain, and those between 21 and 199 shall be set to zero, define the parameters from = 200 and to = 20. Factor, summand: The grey values of the new image are calculated from the grey values of the old one according to the formula GV_new = factor x GV_old + summand. The resulting image has a depth of 8-bit (value range 0 ... 255); factor and summand should be matched with this. Values outside are clipped (= set to the extreme values 0 or 255). Conversion according to table (8 bit): Single or all grey values of an image can be converted with the help of a comparative table (ASCII). This contains rules for the assignment between the current and the new grey values and could look like this: 100 125 110 122 120 200 In doing so all the grey values 100 would be converted to 125, 110 to 122 and 120 to 200. Moreover you can define grey value ranges (from ... to) in the table, e.g.: 50 100 80 101 150 90 In this case grey values from 50 to 100 would be set to 80, those from 101 to 150 to 90. Values not listed in the table can be kept originally or set to free definable value. On the other hand, to generate image masks, values listed in the table can be set to free definable grey value, values not listed to 0. Note 1: Within the options "Level histogram" and "Stretch histogram" (see above) it is possible to generate comparative tables automatically. Note 2: For more sophisticated conversions of grey values the module Data management / Analysis, option Formula calculation, may be used. Numerate areas: The input image must contain areas of each unique colour, for instance as a result of a classification. These areas are numerated, resulting in increasing colour values in the output image. Colour Grey scale image (8 bit): If, for example, a grey scale image was scanned inadvertently as colour image, the IMA file can be converted into a real grey scale image, if palette with the same name exists. This is the case for example after the import of an 8-bit BMP file coming from a scanner.

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Image processing > Image radiometry > Filter In contrast to the point orientated methods described so far filters are environs orientated, therefore calculating the new grey value of the output image from the old one and several others in a square environs, usually called window. Thus, e.g. a 3x3 window consists of the central pixel and its 4 neighbours bordering at the top, at the bottom, on the left, on the right and the four diagonal neighbours. If for a filter one of the parameters window size, threshold or minimum frequency has to be defined, this will be said explicitly. The possibilities in detail are: Filter 1 (grey value or colour images) Mean (smoothing, group of low pass filter): Forming of the arithmetical mean. Example of a 3x3 window: The arithmetical mean of the grey values of the 8 neighbours and of its own grey value is assigned to the respective image point. The filter works by smoothing and gives a less sharp image comparing with the input. Window size 3x3 15x15. Edge preserving smoothing : Has the same effect as a mean filter, provided that the contrast (difference between the maximum and minimum grey value in the window) does not exceed the threshold value (which is to be chosen). Therefore the output image appears less blurred compared to the result of the simple mean filter. Window size 3x3 15x15. Speckle-reduction: For the elimination of disturbed pixels. Provided that the difference between the mean of the grey values of the window and the central pixel is larger than the threshold value (which is to be chosen), the mean will be assigned as the new grey value to the central pixel. Window size 3x3 15x15. Remove line errors: Satellite photos (e.g. LandSat MSS) sometimes show row faults of the kind that individual image rows are partly brighter or darker than their environment. These faults can be eliminated to a large degree by using a special mean filter. A threshold value must be determined ( = maximum distance to the neighbouring rows; 8 bit). Median: Can also be used to eliminate disturbed pixels. Assigns the mean of the grey values of the neighbours, which are arranged in a rising order, to the central element. Window size 3x3 15x15. Majority (filling gaps, e.g. for classification): If the grey value with the maximum frequency reaches the indicated least frequency within the neighbours, the central pixel will also get this value. Suitable for the optical improvement of classification results. Normally, the grey value 0 is not taken into account. Shall this be done, the parameter threshold has to be set to zero. Window size 3x3 15x15. Edge sharpening: The effect of this filter can be set using the parameter Sharpness (between 0 and 1). Window size 3x3 15x15. Local contrast: Within the selected window size (3x3 15x15) the contrast is enhanced. The effect can be increased or decreased using the parameter Threshold. Self-defined: The values of the filter matrix, located in an ASCII file, are to be entered. This for instance consists of 9 values (3 in each row) containing the weight for a 3x3-window (real values also possible). Example: -1 -1 -1 -1 16 -1 (a high-pass filter) -1 -1 -1 The 8 neighbours are each weighed with -1, the central element with 16, the sum is divided by the average value (here: 8) (nomination). If there is a "zero sum filter" (sum of weights = 0) a lifting with the average grey value 127 takes place instead of a nomination. Window size 3x3 15x15. Negative image: Inversion of grey value range 0 ... 255 to 255 ... 0.

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Filter 2 (binary images) Remark: In case of 24 bit images, the third band (red) is used for the following options. Second order equidensities (edges): Calculates the grey value difference between the current pixel and the pixels at the bottom and to the right. If this value lies below the chosen threshold value the new grey value will be 0 (black), otherwise 255 (white). Thus, depending on the image contrast and threshold value, edges can be brought out. If the option "negative image" was chosen, the values 0 and 255 are exchanged additionally. Threshold binarisation: Grey values below the determined threshold value are set to 0 (black), those above to 255 (white). If the option "negative image" was chosen, the values 0 and 255 are exchanged additionally. Shrink or blow up the binary image: Starting from a binary image the objects contained in it (e.g. points or lines with the grey value 255) are modified in such a manner that their border is either reduced by one pixel (shrunk) or broadened. By repetition and combination (e.g. 2x shrinking, then 2x blowing up) complex structures can be simplified for this, the parameter No. of iterations can be used. Negative of binary image: Exchanges the values 0 and 255. Filter 3 (gradients, texture) Remark: In case of 24 bit images, the third band (red) is used for the following options. First derivation (gradient): Forms the difference between the grey values of the current pixel and of one of its 8-neighbours, which is determined by the chosen "aspect". The result is a pseudo-relief. Laplace, blurred mask: High pass filter with strong emphasis on the central element (Laplace: four times with regard to 4-neighbours, blurred mask: eight times with regard to 8-neighbours). It is used for the preparation of the segmentation of an image. Sobel in x (columns) or y (rows): Linear structures in row or column direction will be worked out with the help of difference forming of the current row (column) to the neighbouring row (column). Texture (monotony): For each of the 8-neighbours it is ascertained whether the difference between its own grey value and the grey value of the central pixel does not exceed the chosen threshold. The number of these neighbours determines the new grey value, which gives information about contrast resp. homogeneity in the 3x3 window. Texture (variance): The difference between the highest and the lowest grey value in the 3x3 window forms the new grey value. Image processing > Image radiometry > Noise This option creates a random noise which may be added to an existing input image or stored as new image (dimensions like given in the project definition). The amplitude of the noise can be set between 1 and 255 grey values. Image processing > Image radiometry > Fade out The image borders (width in pixels to be set) will be faded out stepless to the selected grey value.

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Image processing > Image radiometry > 16 8 bit This is used for example in order to have access to the raster display for a digital terrain model (= 16 bit raster image) created in LISA. Procedure: linear (grey value/128), root (from grey value), clipping at grey value 255 or limits (scaling the existing grey values to 1 ... 255). The input image will be maintained. Usually the complete height range is transformed into the interval 0-255. Optionally the height range can be limited. Furthermore the areas which are located within the interval can be fixed at 255 (mask). Image processing > Image radiometry > 8 16 bit This option is to be used if an 8 bit image in the DTM module should be processed like a terrain model (e.g. creating a 3-D-view). The conversion takes place as a linear stretching of the value range 0-255 to the range 0-32767. Important: In order to be able to use the DTM further the image has to be geo-coded (that means the co-ordinates of the lower left corner are known as well as the pixel size), additionally the grey values must have a numerical meaning (terrain minimum and -maximum are known and set, compare menu point for changing header data). If the input image is not geo-coded then the 16 bit variant will be formally geo-coded, meaning corner co-ordinates xmin = 1, xmax = cols, ymin = 1, ymax = rows, pixel size and height range as given in the project definition. Image processing > Image geometry Among others modules for the modification of the image size ("resampling") as well as for the rectification (geo-coding) of a raster image belong to this category. The colour and grey values remain unchanged in contrast to the image radiometry with an exception in the image rectification like described below. As soon as the pixel size of the output image differs from that of the input image, for the calculation of grey values (the so-called resampling) some of work has to be done. To illustrate the problem, let us look at the following example: Imagine, we want to enlarge an image with factor 2 in column and line direction. Then, the grey value of any pixel will be taken over into 4 pixels within the output image. So, here we have no problems. But if we choose a factor of 1.5, the situation changes because "half pixels" doesn't exist. A similar case appears for example during a turning by 15 degrees. For the resampling, several methods exist. LISA offers the two most important: Nearest neighbour: Fast, keeps the original grey values, but gives a coarse appearance especially for

enlargements. Optical, it is the equivalent to a scale changing via photo copy equipment. Bilinear: A bit slower, smoothes the grey values similar to a mean filter by taken into account a 4 pixel

neighbourhood. The result is "nicer" than before but contains mixed pixels. For this changing of grey values see also the note in chapter Image processing > Image radiometry.

So, in all cases where the original grey values are of interest for further operations or the input image is an 8 bit colour image, the first method will be the better. On the other hand, if the optical impression is of higher priority, choose the bilinear resampling. Image processing > Image geometry > Basic functions Turning: The input image can be turned by 90, 180 or 270 degrees (clockwise). Image size and pixel size remain unchanged; when turning by 90 or 270 degrees, the number of rows and columns is exchanged. Further, between -90 and 90 degrees a stepless turn by a given angle is possible. Mirror left-right or mirror up-below: The image dimensions remain unchanged.

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Create image extract: In a geo-coded image by entering the co-ordinates of the lower left and upper right corner of the segment, in a not geo-coded image by entering the first/last row and first/last column. The pixel size remains unchanged. Note 1: The creation of a partial image can also be performed interactively in the image display module (option Measure > Sub image). Note 2: Partial images of a 16-bit-DTM are to be created with the option Mosaic (see below). Note 3: Independent from the input image turned or mirrored images are not geo-coded in any case! Change image size: It is optional whether you enter a percent value or the desired width of the image in pixel or cm. The last choice refer to the output on a printer. The output image will then be extended row- and column-wise in contrast to the input image. Take into consideration that the image size is changed by the square of the factor. Resampling method: Nearest-Neighbour or bilinear (see above). This does not apply to geo-coded images! The stretch factor of geo-coded images (from another project, for instance) is derived from the pixel size of the input image, respectively from the value set in the current project and cannot be changed. Fit to reference image: The dimensions (rows, columns) as well as the header information are taken over from the referential image. The input image starting in the lower left corner will be put into the given frame. Suitable for example if images of a uniform size are necessary for matching. Image processing > Image geometry > Corner co-ordinates For rectifying or geo-coding of a raster image, normally control points are used (see also Image processing, option Measure > Digitise > Prepare rectification). In case the terrain co-ordinates of the image corners are known, these can be used instead of control points and can be put in here. After this, go on with the following chapter. Image processing > Image geometry > Rectification > Numerical For the rectification of a raster image, a special control point file is used containing the values Point No., x, y, row, column of each point. A file like this (standard name GEOCOD.DAT) will be obtained by measuring the control points on the screen (Image display, option Measure > Digitise > Prepare rectification) or by using the previous option for the image corners. Rectification: Is done by a number of control points, optionally done by one of the following methods: Plane similarity transformation (2 points, no adjustment), plane affine transformation (3 ... 900 points, in case of over-determination with adjustment), second order polynomial (4 ... 900 resp. 6 ... 900 points, in case of over-determination with adjustment), projective transformation (4 points, no adjustment), Local / rubber sheet (4 ... 900 points, no adjustment). See also the explanations to the module Orientation of the data input with a digitiser. Selection of transformation method: If only two control points are to be found the plane similarity transformation has to be chosen. For oblique photos the projective transformation is suitable. Otherwise a sufficient over-determination (ca. 10 control points) with an even spatial distribution should be the aim. In case of a draft with non-regular distortions (for example historic maps) the local method ("rubber sheet stretching") will be suitable. The co-ordinate frame for the output image is to be set the option Project limits will use the values from the project definition. In case of an over-determination first the remaining errors of the control points will be calculated and displayed. Points with too huge errors can be deactivated (compare also the option Orientation in the Data input with digitising tablet).

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For testing purposes, instead of rectifying the input image the option Only control image can be used. The program now divides the area of the input image into tiles of 50 x 50 pixels and projects them according to the transformation parameters, so that the geometric effect of rectification can be seen. Besides, the error vectors of the control points in x and y are shown within this option. Note: All transformation methods described above lead in a mathematical view to a transformation of one plane to a second plane parallel to it. So, for the quality of the rectification the input image shall have only overall distortions concerning the scale and so on. In case of aerial photos and especially in mountainous terrain we have in contrary local distortions as a result of the central perspective projection (the so-called radial-symmetrical distortions). If the geometric quality of the output image is not sufficient enough, the only solution is to calculate a so-called ortho image (for example using the LISA module FOTO). Image processing > Image geometry > Rectification > Image to image If a geocoded image exist, another image can be rectified to the geocoded one by a direct measurement of reference points. Middle mouse key: Simultaneous movement of both images. Right mouse key: Movement of only the right image. Left mouse key: Registration of points. Method: Move the images with the middle mouse key pressed until the point of interest is in position with the measurement mark in the left image. Now move the right image with the right mouse key pressed until the respective point is in position with the measurement mark in the right image, then press the left mouse key to save the point data. After a click onto the Ready button the rectification will start (see chapter before). Image processing > Image geometry > Mosaic Only for rectified (geo-coded) images or DTMs. At the same time 1 up to 5 images (DTMs) can be processed. What follows is a dimension control as well as the input for rows and columns of the resulting image if it does not exist already if this is not the case the entered image files will be added. Where two or more images overlap, the grey values are overwritten or averaged. This module is also suitable for the creation of partial images. Then only one input image or DTM will be named. In case of DTMs an additional 8-bit image can be created afterwards. If more than 5 images shall be matched to a mosaic, this option has to be started again. Now, the result of the first time (e.g. MOSAIC.IMA) will be taken as the first input image as well as output image, all others as input image 2 to 5. Within the warning message File already exists then the option Add has to be activated. Beside this, it is possible to use in the first input field (Image 1) "wild cards". For example, if Image 1 = TEST*.IMA, the files TEST1.IMA, TEST2.IMA etc. are used for the mosaic. This option is limited to 1000 images. For large mosaics consisting of very many images, a data base should be used (see below). Image processing > Image geometry > Mounting Can be used for up to 5 images which do not have to be geo-coded. The images may be placed in left-right or top-bottom order. It will be good if all images are of the same size. If more than 6 images are to be matched, this option can be started a second time like its described in the previous option Mosaic. Image processing > Classification (8 bit) A classification can be carried out in a single image as well as parallel in several channels belonging together. The parameters needed can be assigned via an unsupervised classification (cluster analysis) on one hand or a supervised classification (analysis of training areas) on the other hand. The offered methods are the box method (parallel epiped) as well as the minimum distance method. There is a distinction between the channels (= bands, images of different spectrum areas, e.g. visible light, near/medium/thermal infra-red, or colour extracts

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red/blue/green of a colour image) and the classes (= land use, e.g. forest, arable land, grass/meadow, buildings, traffic ways, water). The channels are known to the user, the classes however have to be defined first, e.g. by training areas. These are smaller areas with a homogeneous and known use, whose spectrum characteristics can then be transferred to the whole image. A maximum of five channels can be classified at the same time and a maximum of 50 classes can be differentiated. Cluster analysis (unsupervised classification) Enter the maximum radiometric distance in the cluster, the minimum frequency of each class in percentages , the number of iterations (0 or 1) as well as the names of the individual channels (raster images of 8 bit each). Then the program searches for local accumulations of grey values (one channel) or grey value combinations (several channels), the so-called clusters. The results are stored in the file ANALYSIS.DAT. Note: You may take a value of 10 ... 20 for the maximum radiometric distance in the cluster and ca.1 ... 2% for the minimum frequency in each class. Continue with the item "Define method, start classification" (see below). Process of a supervised classification 1. Definition of the training areas Display one of the channels on the screen. Select the option Measure > Digitise > Register and define the code as 5001 (line) in the corresponding window. Now digitise the border line of the first training area. Take the following into consideration: Within the polygon the grey values ought to be as homogeneous as possible and typical for the respective use; the size should contain at least 200 ... 300 pixels. End the measurement by clicking on the button Close. Repeat the points mentioned above for all training areas. 2. Analysis of the training areas Display each of the possible channels one by one within the display module. Now carry out the following steps in each of the channels: Option Measure > Analysis, name of file for a vector-overlay as above. Now the border polygons of the training areas are shown. Click one by one into the middle of each training area and key in the number of the class. It is important to note the numbering of the classes resp. areas as they must be identical in all channels! Finish with click of the right mouse button; the results of the analysis are stored in the file ANALYSIS.DAT and displayed. Now finish the image display and continue similarly with the next channels if necessary. Define method, start classification Choose the option Image processing > Classification > Method, then the method (box or minimum distance).The suggested names of the input bands (raster image) are taken from the file ANALYSIS.DAT. The parameter used for the classification depend on the method: Box: For each class and channel the limits from ... to of the grey value range (= edge lengths of the n-

dimensional box). Minimum distance: Largest allowed distance from the centre and medium grey value for each class and

channel (= radius and central point vector of the n-dimensional sphere), further for the weighting of each class and channel the standard deviation of the grey values

If needed the result can be processed with the majority filter (see there). Here a more homogeneous appearance is reached, which is of a certain advantage, especially for the output on printer because of its necessary dithering. Note: As a rule a classification is practised on the basis of original data! Radiometric pre-processing (e.g. stretching of contrasts) show no effective additional information . Similar to geometric pre-processing which

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may lead to a loss of information (mixed grey values with average filter or rectification with bilinear resampling). Image processing > Matching (8 bit) In contrary to the combination of images as mosaic or montage (see above), with matching the images are overlaid and the grey values of the output image calculated from the corresponding pixels. For this, the images must have the same dimension (No. of rows and columns). The chosen method is done pixel for pixel, for example addition: The grey values of corresponding pixels in the input images are added and thus produce the grey value in the output image as grey value 1 + grey value 2. Note 1: The entering of a third image is only of relevance for the options directed cosine and pseudo colour image (see below). Note 2: For more sophisticated matching (e.g. with more than two input images or using free-definable formulas) see the option Management / Analysis > Formula calculation. The different possibilities in detail: Addition a) Clipping at white: Sum grey values over 255 are set to the value 255 (white). b) Scaled sum: The resulting grey values are transformed linearly onto the range 0 ... 255. Options: Either the actual value range between the minimum and the maximum or the theoretical possible value range (0 ... 510) will be transformed. The latter case corresponds to the arithmetic mean. c) Weighted addition: "Double exposure". The weight of image 1 can be set between 1 and 99%, image 2 will be weighted with the difference of this value to 100%. See also Others > 2 x 8 bit 24 bit. d) To gap: Only where no information is given in the first image (grey value = 0) the grey values will be taken over from the second image. e) Grey value and colour image, superimposed: Useful for grey scale images which shall be overlaid with colour elements (areas) - these will replace the grey values. The number of colours is limited to 192. d) Grey value and colour image, transparent: Additional to the grey scale image (= image 1) a colour image must exist. Usable are a maximum of 10 colours which will be superimposed transparent to the grey values. Subtraction, masks Remark: A binary image (1 bit) is defined as a mask. It may be used to cut specific content off other images (see the two previous options). a) Clipping at black: Different grey values under 0 are set to the value 0 (black). b) Scaled difference: The resulting grey values are transformed linearly onto the range 0 ... 255. Options are the same as in the addition. c) Absolute sum from image 1 image 2. d) Image 2 as mask, remains maintained: Wherever there is a grey value higher than 0 in image 2 the point will be left blank in the output image (set to 0). Otherwise the grey value from image 1 will be taken over. e) Image 2 as mask, remains away: Exactly the other way round. Division, ratio a) Arcus tangens of image 1 / image 2, increased to mean grey value. b) Scaled quotient: The resulting grey values are transformed linear onto the range 0 ... 255. The quotient can be limited to a maximum value. c) Ratio (NDVI): e.g. for LandSat-TM bands 3 and 4; as formula: (image 2 - image1)/(image 2 + image 1) with image 1 represents the visible red and image 2 represents the near infrared.

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d) Ratio (NDVI) scaled: as before, but scaled to 0 ... 255. Others > Minimum, maximum The minimum or the maximum value from the grey values of the two input images is used pixel-wise as output grey value. Note: The arithmetic mean can be derived with the addition (see above, scaled sum). Others > Directed cosine Is calculated as quotient of the grey values of a channel to the radiometric distance of the respective point from zero (grey value = 0). The individual channels and the selected channel are to be entered. The ratio (quotient) and the directed cosine methods are particularly suitable for the elimination of the influence of varying lighting (e.g. by shadow casting). Others > Colour composite From three channels (raster images of 8 bit each) a colour image with a depth of 24 bit is generated. To aim for a good optical impression it may be useful to bring the single input channels to their maximum contrast first (option Image processing > Radiometry > Histogram > Stretch histogram). Others > True colour image LandSat TM Similar to the Colour composite option but designed particularly for the channels 1, 2 and 3 of image data originating from LandSat-TM satellites. A particular adaptation of the histograms generally leads to a good optical impression. Others > 2 x 8 bit 24 bit Similar to the Double Exposure (see above) but designed particularly for 8 bit colour images (for instance, coloured height representation plus shaded relief, DTM). The result will be stored as a 24 bit image. Image processing > Profile Creates a grey value profile over the input image. The profile trace is determined by points of a vector file which must exist. See also the respective option from the programme part terrain models. Image processing > Area symbols Remark: In case of 24 bit images, the third band (red) is used for the following options. In order to represent grey value or colour images on a black and white printer they have to be dithered. Alternatively to the point-raster method (dithering) offered in the printer program specific area symbols (hatching, point raster) can be used for this purpose. For this a file is to be created first (option Determine grey value symbol). The grey value range (from, to; also possible: from = to), the signature (e.g. hatching 45) and the distance between the lines or points as well as the width of the lines or the thickness of the points are to be entered in pixels. Instead of area symbols, raster images (1 or 8 bit, e.g. scanned graphics) can be used. Overall, grey values from 2 to 254 can be replaced, the values 0 (transparent), 1 (black) and 255 (white) will be kept. If the file is created or exists already the option Carry out area filling can be started. Non-defined grey values of the input image may be kept or replaced by 0 (transparent / background).

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Finally you have the possibility to define your own area patterns (option Create symbols). The signature size (number of rows and columns) and the grey value is to be entered; moreover, a signature already existing can be loaded as a draft. An orientation raster appears left on the screen, a test image right. Depending on the selected tool, points can be set or deleted with the left mouse button. You should take into account that with the continued rowing of the signatures a sensible pattern should result this can be checked in the test image. The finished signature will be stored with a number between 101 and 200, the extension SIG, and can thus be used in the option Determine grey value symbol. The displayed saturation (percentage of defined pixel) makes it easier to create brightness flows. Besides the area filling it is possible to assign the signatures to single points holding the respective code within the vector raster conversion (e.g. code 3501: the signature file 101.SIG is searched for and if needed be entered into the raster image). Newspaper effects: As an alternative to the options described before, the grey or colour values can be replaced by horizontal or vertical lines of different width or a point raster. Note 1: An image in which the grey values were exchanged by an area dithering is highly suitable for a mathematical matching with a same sized grey- or colour image in the sense of a raster overlay. Then the grey- or colour tones are visible through the area dithering (cf. above, Matching > Addition > Clipping at white). Note 2: Self-created symbols (e.g. 101.SIG) are not stored within the working directory but within the common directory c:\lisa\common\sig. Note 3: Normally, only for raster images (extension IMA) the replacement of grey or colour areas by symbols can be done. But, if for the input image a legend (extension LEG) is defined explicitly (with extension), it will be treated in the same way.

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Digital terrain models

This module is used for the calculation and analysis of digital terrain models, hereafter simply named DTM. The following options are available: Vector raster conversion Interpolation of digital terrain model as raster image Calculation of profiles ("1-D") Calculation of the surface representation ("2-D") Calculation of a block image ("3-D") Matching of two DTMs Calculation of areas, volumes and statistics Input data Almost every type of 3-dimensional co-ordinates can be processed. Usually the aim is to produce and process a height model. In order to realise this, a network of well distributed points (= as densely and homogeneously as possible) with the x, y and z (height) co-ordinates being known, is required over the test area. Note that the quality of a terrain model, which means the extent of an agreement with the real terrain, depends primarily on the density and distribution of the input data (reference points). It is therefore absolutely necessary to take the terrain topography into account while collecting the data. A general rule is: The more undulating the terrain the more dense the point network should be. Terrain elements such as edges of steep faces, ridges or V-shaped valley floors should be measured separately and defined as break lines. Local minima and maxima (single points which appear to be higher or lower than their surroundings) have to be entered in the reference point file, too. Instead of height data as the third dimension you may use other numerical data related to locations as well, for example ecological data such as dust or data concerning CO2-pollution, height differences due to soil erosion or dumping etc. In this case an extreme exaggeration factor may be chosen for profiles or block images; it will be suggested by the program. To be able to use the data they must be available as ASCII file and arranged in the sequence (No.) x y z . As far as the program itself is concerned the number of reference points is not limited. Data of very densely neighbouring points will be averaged during the interpolation if need. Codes can denote polylines if needed (see below). The point numbers are without meaning and need not necessarily be available. The code is used to define the following meanings see the appendix, vector data, for more details. Example for a border polygon: 9008 -999999. -999999. 1. 1 1000. 1000. 10. 2 1200. 1200. 10. 3 1050. 1600. 10. 4 1000. 1000. 10. -99 -99. -99. -99.

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Therefore a starting point for deletion:

4007 -999999. -999999. 1. 1 1900. 1900. 10.