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Author Topic: Geometry type requirement for 2D orthomosaic  (Read 7349 times)

realtimeraster

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Geometry type requirement for 2D orthomosaic
« on: July 01, 2013, 07:13:20 AM »
If I am only interested in exporting a 2D GeoTiff and have no need for the 3D DEM, can I simply create a point cloud during the Build Geometry step, or do I still need to have Geometry type be smooth to get the most accurate results?

RalfH

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Re: Geometry type requirement for 2D orthomosaic
« Reply #1 on: July 01, 2013, 10:27:01 AM »
As in so many cases, the answer is it depends. In many cases, creating an orthophoto based on a height field model with "point cloud" selected as geometry type will provide good results, but depending on topography and camera positions you sometimes get better results with higher quality height field models. I suggest doing some comparative tests with what would for you be typical topographies and image acquisition geometries.

airmap3d

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Re: Geometry type requirement for 2D orthomosaic
« Reply #2 on: July 03, 2013, 05:05:20 AM »
I perform UAV mapping over various terrain types and have just run some tests creating orthos from different 'build geometry' setting.  Point cloud vs meduim (smooth) vs high (smooth) produced very similar results.

Personally, I just use point cloud geometry type to extract my orthos as the time involved to build higher quality geometry doesn't seem to yield any significantly better results.

But as RalfH stated, always best to test for yourself as every ones situation is different.

Peter

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Re: Geometry type requirement for 2D orthomosaic
« Reply #3 on: July 03, 2013, 08:43:02 AM »
If i only want ortho i use point cloud geometry for export, roads can sometimes not align properly but for forestry the trees look moore natural.

Would aligning at high setting help to improve the quality of ortho when exporting with point cloud geometry?

What aligment settings do you guys use for large uav projects, over 500 pics as an example.

airmap3d

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Re: Geometry type requirement for 2D orthomosaic
« Reply #4 on: July 03, 2013, 01:49:49 PM »
I use the high setting and always have done.  I utilize the sparse point cloud though to create DEM's so I need to use high, any lower and the sparse point cloud is a little too sparse.

Peter

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Re: Geometry type requirement for 2D orthomosaic
« Reply #5 on: July 03, 2013, 03:07:40 PM »
Yes Align on high and sparse pointcloud seem to do it for most cases