Tutorial BL Orthophoto DEM With GCP

8/13/2019 Tutorial BL Orthophoto DEM With GCP

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First run tutorial:

Orthophoto and DEM Generation with Agisoft PhotoScan Pro

0.8.

!with Ground "ontrol Points#

PhotoScan settingsOpen PhotoScan Preferences dialog from $ools menu using corresponding

command.

Set the following values for the parameters in the General tab:

Maximum points per photo:%0000

P1:%0

P2:&000

Write log to file:specif' director' where Agisoft PhotoScan log would (e stored

(in case of contacting the software support team it could be required)

Project compression level:)

Enable stereo mode:Disa(ledEnable V! support:Disa(led

"hec# for updates on program startup:Ena(led

Set the parameters in the Open"*tab as following:

"hec+ on an' Open"* de,ices detected (' PhotoScan in the dialog and reduce the

nu-(er of acti,e "P cores (' one for each Open"* de,ice ena(led !if 'our "P

supports h'per/threading then two acti,e "P cores per each Open"* de,ice

should (e disa(led#.

$dd photosSelect the Add Photos...command from or+flowmenu. In theAdd Photosdialog

browse the source folder and select files to be processed. Click Openbutton.


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$dd ground controlt this step coordinate s!stem for the future model is set using camera positions.

Open Ground "ontrolpane using the corresponding command from the 1iewmenu.

Click 2-portbutton on the Ground "ontrolpane toolbar and select file

containing camera positions information in the Opendialog."he easiest wa! is to load simple character#separated values file ($.t%t) that contains

%# and !# coordinates and height for each camera position (camera orientation data&

i.e. pitch& roll and !aw values& could also be imported& but the data is not obligator!).

In2-port "S1dialog indicate the delimiter according to the structure of the file and

select the row to start loading from.

'ote that rows are numbered starting from ero * character indicates a commented

line that is not counted while numbering the rows.

Indicate for the program what parameter is specified in each column through setting

correct column numbers in the "olu-ns section of the dialog. Columns are

numbered from ero as well. Check !our settings in the sample data field in 2-port

"S1dialog:

Click O3. "he data will be loaded into the Ground "ontrolpane.

"hen click on the Settings button in the Ground "ontrol pane and in the

Ground "ontrol Settingsdialog select corresponding coordinate s!stem from

the list.


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Click O3 and camera positions will be marked in +odel view using their

geographical coordinates:

$lign photost this stage ,hotoScan refines the camera position for each photo and builds the

sparse point cloud model.

SelectAlign Photoscommand from the or+flowmenu.

Set the following values for the parameters in theAlign Photosdialog:

$ccurac%:4igh

Pair preselection:Ground control"onstrain features b% mas#:Disa(led

Click O3to start photo alignment.


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Place mar#ers+arkers are used to optimie camera positions and orientation data& which allows for

better model reconstruction results& and for precise georeferencing.

"o generate high qualit! orthophoto at least - ground control points (/C,) should

be marked evenl! within the area to be processed.

"o be able to follow guided marker placement approach (that would be faster and

easier) !ou need to reconstruct geometr! first.

Select 5uild Geo-etr'... command from the or+flow menu and specif! the

following parameters in the5uild Geo-etr'dialog:

Click O3.

"hen& when the geometr! is built (it usuall! takes a few seconds)& open a photo

where a /C, is visible inPhoto 1iewdouble#clicking on its icon in the or+space

pane. Switch to marker editing mode using Edit Mar+erstoolbar button. 0oom in

to locate the /C, on the photo and place a marker in the corresponding point of the

image using "reate Mar+er command from the conte%t menu available b! right#clicking on the opened photo in the corresponding position:


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Select the marker on the Ground "ontrol pane. "hen filter images in Photo pane

using Filter (' Mar+erstoolbar button.

'ow !ou need to check the marker location on ever! related photo and refine its

position if necessar! to provide ma%imum accurac!. Open each photo where the

created marker is visible. 0oom in and drag the marker to the correct location usingthe mouse in the Edit Mar+ers mode.

1epeat the described step for ever! /C,.

&nput mar#er coordinates+arker coordinates should be imported from a file. Click 2-port button on

the Ground "ontrolpane toolbar and select file containing /C, coordinates data in

the Opendialog. "he easiest wa! is to load simple character#separated values file

($.t%t) that contain markers name& %#& !# coordinates and height.

In2-port "S1dialog indicate the delimiter according to the structure of the file and

select the row to start loading from.

'ote that rows are numbered starting from ero * character indicates a commented

line that is not counted while numbering the rows.

Indicate for the program what parameter is specified in each column through setting

correct column numbers in the "olu-ns section of the dialog. Columns are

numbered from ero as well. Check !our settings in the sample data field in 2-port

"S1dialog:


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Click O3. "he data for markers will be loaded into the Ground "ontrolpane."hen click on the Settingsbutton in the Ground "ontrolpane and in the Ground

"ontrol Settings dialog select corresponding coordinate s!stem from the list

according to the /C, coordinates data.

Set the following values for the parameters in Measure-ent accurac'section:

"amera accurac%:60

Mar#er accurac%:0

Projection accurac%:0.6

Click O3.

!ptimi'e photo alignment"o achieve higher accurac! in calculating camera e%ternal and internal parameters

and to correct possible distortion (e.g. 2bowl effect3 and etc.) optimiation

procedure should be run. "his step is especiall! recommended if the ground control

points coordinates are known almost precisel! (several centimeters accurac!).


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On the Ground "ontrolpane uncheck all photos and check the markers to be used in

optimiation procedure. "he rest of the markers that are not taken into account can

serve as control points to evaluate the optimiation results.

Click Opti-i7ebutton on the Ground "ontrolpane toolbar.

Select all camera parameters. Click O3to start optimiation process.

Set bounding box"his step is optional since ,hotoScan automaticall! calculates bounding bo%dimensions and location. It is recommended& however& to check if an! correction is

needed as geometr! reconstruction procedure is applied onl! to the area inside the

bounding bo% and odd points e%clusion ma! speed up the process.

4ounding bo% is resiable and rotatable with the help of esi7e region and

otate regiontools from the $ool(ar.

Important: $he red/colored side of the (ounding (o9 indicates the plane that would

(e treated as ground plane and has to (e set under the -odel.

uild geometr%

56 model reconstruction is a computationall! intensive operation& it can take a longtime& depending on the quantit! and resolution of loaded photos and selected target

qualit!.


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Select5uild Geo-etr'command from the or+flowmenu:

Set the following values for the parameters in the5uild Geo-etr'dialog:

!bject t%pe:4eight/field(arget )ualit%:Mediu-

*eometr% t%pe:S-ooth

+ace count:&000000

+ilter threshold:0

,ole threshold:60

Click O3to start building geometr!.


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*enerate orthophotoSelectE9port Orthophoto#7E9port PEG;$2FF;P


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*enerate -EMSelectE9port DEMcommand fromFilemenu.

Set the following recommended values for the parameters in theE9port DEMdialog:

Projection t%pe:Geographic

Projection:b! default the pro8ection set in the /round Control Settings is used

"rop invalid -EM:Ena(led

.o/data value:Default ,alue

Pixel si'e:Default ,alueSplit in bloc#s:Disa(led

Setup boundaries:Disa(led

Click E9port... button and then specif! target file name and select t!pe of the

e%ported file (e.g. /eo"I99). Click Sa,ebutton to start 6+ generation.

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Tutorial BL Orthophoto DEM With GCP