A DAT/EM Systems International White Paper • October 2012

Landscape™

Stereo Viewing and Editingfor LIDAR Point Files

DAT/EM Systems International, 8240 Sandlewood Place, Suite 101, Anchorage, AK 99507 USATel (907)522-3681 • Fax (907)522-3688 • E-mail sales@datem.com • Web www.datem.com

LANDSCAPE: Stereo Viewing and Editing for LIDAR Pointsa DAT/EM Systems International White PaperLast Document Edit Date: October 30, 2012

Copyright © DAT/EM SYSTEMS INTERNATIONAL 2012Made in U.S.A.

For questions concerning this document, contact:

DAT/EM Systems International8240 Sandlewood Place, Suite 101Anchorage, Alaska 99507 USAPhone (907) 522-3681Fax (907) 522-3688www.datem.com

Trademark Acknowledgements3Dconnexion, SpaceExplorer, SpaceNavigator, and SpacePilot are registered trademarks of 3Dconnexion Holding S.A. Corporation Switzerland. Stealth Mouse is a trademark of ABC Software Developers. CONTOUR CREATOR, DAT/EM CAPTURE, LANDSCAPE, and SUMMIT EVOLUTION are trademarks of DAT/EM Systems International. SoftMouse is either a trademarks or registered trademarks of GGS. Windows XP and Windows Vista are registered trademarks of Microsoft Corporation. All other product names mentioned herein are used for identification purposes only, and may be the trademarks or registered trademarks of their respective companies.

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LANDSCAPEStereo Viewing and Editing for LIDAR Point Files

A DAT/EM Systems International White Paper

Contents

Summary.............................................................................................................................1

Landscape Hardware and Operating System Requirements ........................................1

License Options ..................................................................................................................2

File Formats........................................................................................................................2

Input and Output Point File Formats ............................................................................2Input and Output Vector File Formats..........................................................................3

The Landscape Project File...............................................................................................3

Viewing and Navigation ....................................................................................................4

Point, TIN, Surface Viewing, and Coloring Choices ...................................................4View Rotation and Zooming ........................................................................................5Snap Z to Surface .........................................................................................................6

Tools ....................................................................................................................................6

Point Selection Methods ...............................................................................................6Interactive Point Editing Tools.....................................................................................7

Automatic Point Editing Tools..........................................................................................9

Elevation Contour and TIN Generation Tools ...........................................................13Vector Loading and Drawing Tools ...........................................................................13Vector Superimposition ..............................................................................................13

Contact DAT/EM Systems International.......................................................................14

Summary

LandscapeStereo Viewing and Editing for LIDAR Point Files

Summary Aerial and terrestrial LIDAR (Light Detection and Ranging) is widely used to create point clouds representing the ground surface and objects on the ground. LIDAR file output typically contains millions of points, which require review for proper classification and preparation for future use. LANDSCAPE is used to view, edit, and process these point clouds in the following ways:

• View LIDAR points in stereo and from any view rotation or viewpoint distance.

• Filter LIDAR points for viewing based on criteria such as class and elevation.

• Edit LIDAR points and many other formats of XYZ data files. A common editing task would be to reclassify points.

• Offer vector drawing tools. A common vector drawing task would be to create breaklines, which are used as input for automatic contour generation.

• Provide additional tools such as CONTOUR CREATOR, DAT/EM’s automatic contour generation tool.

LANDSCAPE may be used alone or together with DAT/EM’s SUMMIT EVOLUTION stereoplotter for simultaneous stereo aerial image viewing and/or with DAT/EM CAPTURE for direct digitizing into AutoCAD or MicroStation.

LANDSCAPEHardware and

Operating SystemRequirements

LANDSCAPE has specific requirements for the computer and peripheral hardware:

• Computer. Before purchasing a computer to run LANDSCAPE, please visit www.datem.com for the most current list of required computer hardware.

• Operating System. LANDSCAPE operates under the Windows® XP and Windows 7 operating systems. Before purchasing or upgrading the operating system, and to check on 32-bit and 64-bit compatibility, please visit www.datem.com for the most current list of required operating system versions.

• Stereo viewing hardware. Before purchasing stereo viewing hardware to run LANDSCAPE, please visit www.datem.com for the most current list of required stereo viewing hardware.

• 3D input device. The following 3D input device options are compatible with LANDSCAPE:

• GGS or Immersion® SoftMouse™

• ABC Software Developers Stealth Mouse™ (some models)

• 3Dconnexion® SpaceNavigator™, SpaceExplorer™, or SpacePilot™

• DAT/EM Systems International handwheels and foot disk

Note that while the 3D device works to control the 3D position of the LANDSCAPE cursor, the regular system mouse is still present and still works as the usual system pointing device.

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License Options

License Options LANDSCAPE may be licensed for use:

• Alone.

• Together with the DAT/EM SUMMIT EVOLUTION stereoplotter. Either one may control the cursor of the other. SUMMIT EVOLUTION must have a project with imagery in the same area as the LANDSCAPE LIDAR points project.

• Together with DAT/EM CAPTURE for AutoCAD or MicroStation. LANDSCAPE acts as a 3D digitizer for AutoCAD or MicroStation.

File Formats LANDSCAPE accepts many file formats for point files, vector files, and vector file output. These are outlined below.

Input and OutputPoint File Formats

The most commonly used input point formats are LIDAR point files, but many other formats from other sources are accepted. They will all be referred to as “LIDAR files” in this document, because LIDAR files comprise the majority of input files.

LANDSCAPE saves and outputs most edited file formats under the same format as the original input file. Some formats may not be saved under their original format, but may be translated by the included Point Translator tool into a format that can be edited and saved.

Table 1: LANDSCAPE Point Input/Output Formats as of March 2010

File Extension Description

.las LIDAR files, including LAS 1.2 format files that contain color.

.bin, .prj TerraScan files, including 16-bit .bin files.

.sdtm SUMMIT EVOLUTION DTM files

.bil, .hdr BIL files

.asc, .grd, .adf ESRI grid files

*.CATD.DDF SDTS

.dem USGS DEM

.dxf CAD files, drawing exchange format

.shp ESRI ArcGIS shapefiles

.dt0, .min, .max, .avg DTED

.txt, .xyz Text files. The file must contain (X, Y, Z) coordinates and the user must be able to identify the contents of the line format.

.sdt ISM DiAP files

.img ERDAS IMG files

.pix PCI PIX format

.pts Leica PTS

.tif, .tiff TIFF with embedded DEM

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The Landscape Project File

Input and OutputVector File Formats

LANDSCAPE can also import and output vector files. These vector files are used for viewing and with the drawing tools shown below in “Vector Loading and Drawing Tools” on page 1-13. The following vector file formats may be input and output:

The LANDSCAPEProject File

The LANDSCAPE project file contains a list of LIDAR point files and settings choices. The user creates the project file from within LANDSCAPE by browsing for files or dragging and dropping them into the LANDSCAPE application window. More files may be added at any time, or files may be unchecked or removed at any time.

This very simple LANDSCAPE project contains 12 .bin files. It is shown in the initial state before screen rotation, zooming, point filtering, displaying

as a TIN or filled surface, or opening information windows.

Table 2: LANDSCAPE Vector Input/Output Formats as of March 2010

File Extension Description

.dwg Autodesk AutoCAD drawing files

.dxf CAD files, drawing exchange format

.shp ESRI ArcGIS shapefiles

.dgn Bentley MicroStation design files

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Viewing and Navigation

Viewing andNavigation

The user has many viewing and navigation choices within LANDSCAPE. These are outlined below.

Point, TIN, SurfaceViewing, and

Coloring Choices

As LIDAR files are loaded, there are several choices for how to view them:

• Points only

• TIN (Triangulated Irregular Network) only

• TIN and Points

• TIN with Filled Surface, with or without surface lighting

Conceptual example of “Points Only” setting.(The actual view would be enhanced by stereo display)

Conceptual example of “TIN Only” setting.(The actual view would be enhanced by stereo display)

Conceptual example of “TIN and Points” setting.

Conceptual example of “TIN with Filled Surface” setting.

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Viewing and Navigation

All of these display options may be affected by the following filtering and coloring choices.

• LIDAR filters. The user sets up filters based on class, flight line, intensity, return number, and time stamp. This is the most rigorous type of filter; filtered points are not loaded, and do not take part in the project until the filter is removed. Different filters may be applied to different files.

• Display by class. Classes are all loaded, and may be toggled on and off quickly. The user may also choose display colors for each class.

• Color by class. Each class is colored by a default or user-defined color.

• Color by elevation. Rainbow-like colors are used to color points by elevation, with blues at the lowest elevations and reds at the highest elevations.

• Color by flight line. All points in a certain flight line receive the same color, and each flight line receives a different color.

• Color by return number. A point is colored based on its LIDAR return number.

• Color by intensity. This option may be used alone or with the other coloring options. For example, “color by elevation” can be further enhanced with intensity levels.

• Color by orthophoto image or RGB. To color by orthophoto image, one or more orthophotos for the area must be loaded. Points are colored based on the closest pixel colors for the matching XY in the orthophoto. If the points have RGB colors associated with them in their file format, this setting activates the points’ own colors.

View Rotation andZooming

There are several choices for zooming and moving the user’s viewpoint in the LANDSCAPE view:

• New window. Using the system mouse, drag a window on the project overview. The main view zooms to the window.

• Pick a location. Using the system mouse, click a location on the project overview. The cursor moves to that location and automatically sets the Z of the closest point.

• Rotate in 3D. Use the 3D cursor’s “Rotation Clutch” button to drag the main view to the desired 3D orientation. Use another button to quickly reset the view.

• Profile View. Select a specific area. The main view zooms to the area, and the points contained in the profile area are shown in the profile view for viewing by elevation.

• Pan. Move the 3D cursor on the table surface to pan with fine movement; use the 3D cursor’s “Pan” buttons to pan more quickly; use the system mouse and the “hand cursor” to pan the main view in XY.

• Change the elevation: Use the 3D cursor’s Z wheel alone to change the elevation; use the system mouse and the “hand cursor” to pan the elevation in the profile view.

• Change the viewpoint height above the cursor: Use the 3D cursor’s clutched Z wheel or the system mouse wheel to change the viewpoint height with respect to the cursor location.

• Zoom to selected files: Highlight files in the project list and choose “Zoom to Selected Files” to fit these file areas into the main view.

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Tools

Snap Z to Surface Snap to Surface and Follow Surface set the cursor to the elevation of the surface.

• Snap to Surface. Sets the cursor elevation to the elevation of the surface that the (x,y) of the picked location. This is a one-time-per-pick elevation snap. Set this on a digitizer button or activate it from a toolbar and the system mouse.

• Follow Surface. Constantly snaps the cursor to the elevation of the surface as the cursor moves. Either follow all available points or apply filters in order to follow the elevations of certain types of points.

Tools LANDSCAPE offers tools for point editing, contour viewing and generation, and vector manipulation. LANDSCAPE may work alone or together with DAT/EM SUMMIT EVOLUTION to accomplish point editing tasks. These tasks are outlined below.

Point SelectionMethods

LANDSCAPE offers the following point selection tools.

• Select points using the system mouse cursor. Activate the selection tool and select the points in the main view.

• Select points using a fence. Activate the fence selection tool and draw a fence polygon around points using the LANDSCAPE cursor. Draw more fence polygons to add to the selection.

• Select points around the cursor path. A circle of a user-set size appears around the cursor. Move the cursor to select points along the circle's path.

• Select points using Selection Sets. Selection sets offer an advanced point selection method. Default sets are “All points” and “Currently Selected Points.” The user may define custom selections sets, which describe points based on properties such as class and flight line or where they are with respect to polygons or polylines in vector files. Examples: Define a selection set to select points on Class 3 and Class 4; Define a selection set to select all points that lie inside polygons on the “building” layer/level in a vector file; Define a selection set to select all points that lie within a certain distance of polylines on the “breakline” layer/level in a vector file.

Selection Sets are used to provide the input for tools such as the Breakline Filter and Reclassify Points tools. Selection Sets may be saved and used any number of times.

Draw “fence” polygons around areas to select the points inside the polygons.

Move the cursor to select points along the cursor’s path.

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Tools

Interactive PointEditing Tools

LANDSCAPE offers the following interactive point editing tools.

• Reclassify Selected Points from Point Properties Display. This option changes the class of one or more selected points. Select points either by manually picking or with a user-defined selection set. Set the new value in the Point Properties window and apply to either a single or all selected points. This may be used, for example, to select a group of high points from the profile window and classify them as bird strikes.

• Delete Selected Points. This option deletes selected points. Select points by manually picking or with a user-defined selection set.

• Edit Points Around Lines. This is an interactive version of the Breakline Filter tool shown below in the automatic tools. The user draws the polyline and the points near it are deleted, moved, and/or changed, depending on the settings.

The point’s class is changed to class 8 high point.

A point that is far above the surface is selected. It is a class 1 unclassified point.(Multiple points can be changed at the same time.)

After deleting selected pointsPoints are selected

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Tools

• Interactive Point Editing with the LANDSCAPE or SUMMIT EVOLUTION Cursor. Individual points may be moved in XYZ or Z only using either the LANDSCAPE cursor or the DAT/EM SUMMIT EVOLUTION cursor. Running SUMMIT EVOLUTION together with LANDSCAPE is optional, but it has the advantage of additional tools and viewing points superimposed on a stereo image view:

› Edit points interactively› Shift a single point to a new location› Lock point’s XY during shift (shift elevation only)› Shift points to match a surface (otherwise known as “Face Shift”)

With the Edit Points Interactively and Shift a single point... tools on, the closest point in XY to the cursor is highlighted to indicate which point will be edited. In either LANDSCAPE or SUMMIT EVOLUTION, adjust the 3D cursor to the new location and pick to move the highlighted point to the cursor coordinate. The Lock piont’s XY... tool may be active at the same time to make sure the point moves in elevation only.

LANDSCAPE can edit points interactively using its own cursor or the SUMMIT EVOLUTION cursor. For LANDSCAPE alone:

• The nearest point to the cursor is highlighted.

• The LANDSCAPE cursor picks a new XYZ or Z-only position for the highlighted point.

• The point moves in LANDSCAPE.

(Optional) SUMMIT EVOLUTION may be running and may be controlling the LANDSCAPE cursor.

• SUMMIT EVOLUTION must open a stereo model in the same geographic area and the same coordinate system as the LANDSCAPE project.

• The LANDSCAPE points are superimposed over the stereo image view. The nearest point to the cursor is highlighted.

• The SUMMIT EVOLUTION cursor picks a new XYZ or Z-only position for the highlighted point.

• The point moves in LANDSCAPE and updates in the SUMMIT EVOLUTION view.

DAT/EM SUMMIT EVOLUTION

DAT/EM LANDSCAPE

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Automatic Point Editing Tools

To use Shift points to match a surface (otherwise known as “Face Shift”), first draw a polygon, polyline to offset, or a series of points with SUMMIT EVOLUTION. A TIN is constructed from the input. Points move onto the surfaces defined by the TIN.

Automatic PointEditing Tools

LANDSCAPE offers the following automatic point editing and reclassification tools.

• Air Points Filter. Classifies points that are clearly higher than the median elevation of surrounding points. It can be used to classify “noise” up in the air. When possibly classifying one point, this routine will find all the neighboring source points within a given search radius. It will compute the median elevation of the points and the standard deviation of the elevations. The point will be classified only if it is more than a limit times the standard deviation above the median elevation. Comparison using standard deviation results in the routine being less likely to classify points in places where there is more elevation variation.

• Bare Earth Filter. The Bare Earth filter analyzes points to meet bare Earth criteria and either reclassifies the points or removes all other points.

• Below Surface Filter. Classifies points that are lower than other neighboring points in the source class. This routine can be run after ground classification to locate points that are below the true ground surface. The algorithm for this routine can be outlined as follows: For each point (central point) in the source class, find up to 25 closest neighboring source points; fit a plane equation to the neighboring points; if the central point is above the plane or less than Z tolerance below, it will not be classified; compute standard deviation of the elevation differences from the neighboring points to the fitted plane; if the central point is more than a limit value times the standard deviation below the plane, classify it into the target class or delete the point.

“Face Shift” is a tool that may be used when editing interactively with SUMMIT EVOLUTION

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Automatic Point Editing Tools

• Breakline Filter. This option deletes, changes the class, or keeps points within a set distance of vector breaklines. Vector polylines must be available in a .dwg, .dxf, .shp, or .dgn file. This tool deletes, keeps, or changes points based on separate XY and Z distances from the polylines. It searches through all points, selected points, or points defined in a selection set. This tool may be used, for example, to prepare input for contour generation so that breaklines and point input are not at the same XY location.

After “breakline filter” with the “delete within” option

Before “breakline filter”

After “breakline filter” with the “delete beyond” option.

Before “breakline filter”

After “breakline filter” with the “change class” option

Before “breakline filter”

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Automatic Point Editing Tools

• Building Classification Filter: Classifies building rooftops and outside walls.

• Isolated Points Filter. Classifies points that do not have very many other points within a 3D search radius. This is useful for finding isolated points up in the air or below the ground. When possibly classifying one point, this routine will find how many neighboring points there are within a given 3D search radius. It will classify the point if it does not have enough neighbors.

After building and water classifications filters

Points before classification filters

Zoomed-in view of an area of Building Classifications

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Automatic Point Editing Tools

• Key Points Filter: The Key Points filter acts as a "point thinner" to extract a smaller data set. The least amount of points extracted may be defined using the highest and lowest point in each cell of a grid (two points per cell). If a tolerance is used, more points are included per cell to better represent the surface.

• Low Points Filter. Classifies points that are lower than other points in the vicinity. It is often used to search for possible error points which are clearly below the ground. This will compare the elevation of each point (center point) with every other point within a given xy distance. If the center point is clearly lower than any other point, it will be classified. If there are several error points close to each other, those will not be detected if searching for single low points; however, this routine can also search for groups of low points where the whole group is lower than other points in the vicinity.

• Reclassify Points by Selection Set. This reclassifies points that are selected by selection sets rather than by user selections.

• Water Classification Filter: Classifies flat or almost flat water. See example together with Building Classification above.

• Z (Elevation) Filter. This option deletes or changes the class of points based on elevation above and/or below set Z values. It searches through all points, selected points, or points defined in a selection set.

“above” limit

“below” limit

Surface Z for this grid cell area

This point would become a key point

This point would not become a key point

This point would not become a key point

This point would become a key point

+z

-z

(based on current key point set)

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Simplified concept of Maximum...below and Maximum...above settings in the Key Point filter.

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Automatic Point Editing Tools

Elevation Contourand TIN Generation

Tools

LANDSCAPE offers the following elevation contour and TIN generation tools:

• Contour Visualization. This tool is used to prepare and verify input before actual contour generation. It shows temporary contours and/or TIN lines in the view. The contours/TIN lines are based on the points loaded in the view and any breaklines from loaded vector files. The user views the temporary contours and/or TIN lines to determine whether the input is correct or whether it requires editing.

• Contour Generation. DAT/EM’s CONTOUR CREATOR is supplied with LANDSCAPE. CONTOUR CREATOR generates contours based on point files and vector input such as breaklines, soft breaklines, borders, and exclusion areas. It detects depression contours. It outputs contours and/or TIN lines. It outputs to vector files in .dwg, .dxf, .shp, or .dgn format. If DAT/EM CAPTURE is licensed and AutoCAD or MicroStation is running, it can also output directly to AutoCAD layers or MicroStation levels.

Vector Loading andDrawing Tools

LANDSCAPE offers tools to load vector files and draw new vector objects:

• Load vector files. Load existing files in .dwg, .dxf, .shp, and .dgn formats.

• Draw new polylines: Draw polylines in point-to-point or streamed vertex mode, polylines with squared segments, arcs (simulated by many polyline vertices), or circles (also simulated by many polyline vertices).

• Draw new points. Digitize new points. These are vector objects; they are not considered LIDAR points and are not combined with any of the point file input.

• Label spot elevation points. Place elevation text next to point objects.

• Draw new text objects: Two text placement tools are provided. One is for simple text, the other keeps a list of labels that may be used again at any time.

• Edit drawing objects. Tools are provided to edit existing objects.

Resulting vector objects may be exported to .dwg, .dxf, .shp, or .dgn format files.

Vector files are most often used to prepare input for contour generation (see “Elevation Contour and TIN Generation Tools” on page 1-13).

Note that if DAT/EM CAPTURE is licensed on the computer and AutoCAD or MicroStation is running, vector objects may be drawn directly from LANDSCAPE into AutoCAD or MicroStation. In this case, all of the DAT/EM CAPTURE, AutoCAD, or MicroStation vector drawing and editing tools would be available. Vector objects in AutoCAD or MicroStation would be superimposed in the LANDSCAPE view, but would be edited from within AutoCAD or MicroStation.

VectorSuperimposition

Vector superimposition is supplied as part of the LANDSCAPE if the SUMMIT EVOLUTION stereoplotter or DAT/EM CAPTURE is also installed. With SUMMIT EVOLUTION, superimposition displays LANDSCAPE’s points and vector objects in SUMMIT EVOLUTION’s main view. With DAT/EM CAPTURE, superimposition displays CAD vectors in LANDSCAPE’s main view.

Vector superimposition makes it easy to see features that have been digitized and to verify that they are correct in X, Y, and Z. Superimposition also make it easy to find data omissions. Superimposed vectors appear “on the ground” when their Z values match the actual ground in the images or points in the LIDAR files. It is easy to see where a digitized object matches or diverges from the other data; an object at the wrong elevation appears to “float in the air” or be “under the ground.”

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Contact DAT/EM Systems International

Contact DAT/EMSystems

International

Please contact DAT/EM Systems International for more information or for a referral to your local distributor:

www.datem.com Visit the DAT/EM Systems International website.

sales@datem.com Email DAT/EM Systems International for a knowledgeable technical discussion, sales information, and referrals to local distributors.

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About DAT/EM Systems International

DAT/EM Systems International is a leader in the development of software for digital mapping and photogrammetric applications. Currently, DAT/EM serves over 500 photogrammetric production companies, engineering firms and government agencies in more than 70 countries worldwide.

DAT/EM takes pride in a reputation for delivering quality systems and superior customer support. With an ever-changing technological climate in the mapping world, DAT/EM stays committed to continued development and implementation of state-of-the-art software and hardware for digital mapping applications.

DAT/EM employs highly technical and creative personnel, integrates cutting-edge technology and performs its business transactions in an honest and open manner.

DAT/EM Systems International8240 Sandlewood Place, Suite 101Anchorage, Alaska 99507 USA

Telephone: (907)522-3681Fax: (907)522-3688E-mail: sales@datem.comWeb: www.datem.com