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Author Topic: DEM edges with no data, from of cleaned dense cloud  (Read 3119 times)

obw

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DEM edges with no data, from of cleaned dense cloud
« on: July 17, 2017, 10:23:10 AM »
Hi there.

I've cleaned my dense cloud around the borders and used the compact dense cloud function. Still when I create a DEM from dense cloud as source, it uses the entire sparse cloud area as a source, which then results in a DEM with no data around the edges. See Attached example.

Is there a workaround for this? I'm creating 5 models which are overlapping, so I need the edges to be sharp with correct data.

Alexey Pasumansky

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Re: DEM edges with no data, from of cleaned dense cloud
« Reply #1 on: July 17, 2017, 11:39:33 AM »
Hello obw,

You can disable the interpolation option in the Build DEM dialog, otherwise PhotoScan will interpolate the elevation for the areas seen from at least one camera.

Also before exporting you can use polygonal shape defined as outer boundary to save DEM with straight boundaries.
Best regards,
Alexey Pasumansky,
Agisoft LLC

obw

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Re: DEM edges with no data, from of cleaned dense cloud
« Reply #2 on: July 17, 2017, 12:54:24 PM »
Allright, thank you Alexey.

So I would like to keep the interpolation to not get a lot of holes in my DEM (removed buildings etc) and still keep the edges sharp. So if I understand you correctly I can just create a shape around the area I want to export inside, but where do I choose this from the export menu? I can only see the setup boundary settings which I presume uses the bounding Box coordinated?

And since we're talking about exporting, how do i make the no data section transparent, and not solid background?

Thanks a lot for all the help :)

Alexey Pasumansky

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Re: DEM edges with no data, from of cleaned dense cloud
« Reply #3 on: July 17, 2017, 01:02:05 PM »
Hello obw,

You need to draw the polygonal shape in the Ortho view mode, then right-click on it and assign Outer Boundary type to it.

All shapes defined as boundaries will be automatically applied during orthomosaic and DEM export.

As for No-data value, you can select the desired value in the Export DEM dialog.
Best regards,
Alexey Pasumansky,
Agisoft LLC

obw

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Re: DEM edges with no data, from of cleaned dense cloud
« Reply #4 on: July 17, 2017, 01:13:59 PM »
Thanks a lot for your help, the boundaries helps a lot!

So what value is transparent? -32767?

Jeremiah_ROWE

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Re: DEM edges with no data, from of cleaned dense cloud
« Reply #5 on: July 18, 2017, 04:00:11 PM »
Thanks a lot for your help, the boundaries helps a lot!

So what value is transparent? -32767?

Depends on what software you are feeding the data into. The NoData input value can generally be set by the user, however there are some general defaults in some programs, like -32767. I believe its generally related to the bit-depth.