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Author Topic: Orthomosaic generation  (Read 3502 times)

Mfranquelo

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Orthomosaic generation
« on: August 12, 2015, 12:26:18 PM »
Dear All,

I am new on this Agisoft feature, Orthomosaic building. I've read on another topic that it wouldn't be needed to generate the mesh in order to create the orthomosaic on version 1.2.0 (I might be wrong however). I've just generated the dense cloud but the "Build Orthomosaic" "Build DEM" are on grey.

Am I doing something wrong? Should I select something first?  :-\

Thanks!  :)

Alexey Pasumansky

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Re: Orthomosaic generation
« Reply #1 on: August 12, 2015, 12:33:56 PM »
Hello Mfranquelo,

It's better to post the questions on 1.2 version in the corresponding thread, but anyway, Orthomosaic can be generated if DEM or Mesh are present in the project. DEM can be generated if Dense Cloud or Mesh are present AND actual chunk is referenced.
Best regards,
Alexey Pasumansky,
Agisoft LLC

Mfranquelo

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Re: Orthomosaic generation
« Reply #2 on: August 13, 2015, 01:03:58 AM »
Thank you Alexey, it is working now. (I am sorry about the 1.2 version thing)

However the Orthomosaic looks very strange, just like it has been projected on a wrong plane:
- This is my workflow:

1. Generate sparse point cloud using 0 tie point and 40.000 key point limit. Would my Orthomosaic be more precise if I generate more points on my sparse cloud?

2. Generate dense cloud. High. Moderate filtering mode
3. Build DEM (Coordinate system comes automatic) Source data: Dense cloud
4. Build Orthomosaic I can't change the projection from Geographic to planar (this might be the problem?)
5. Export Orthomosaic

Thank you,
Manuel Franquelo.

Mfranquelo

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Re: Orthomosaic generation
« Reply #3 on: August 13, 2015, 04:52:55 PM »
Any thoughts on this Alexey?  :)


Alexey Pasumansky

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Re: Orthomosaic generation
« Reply #4 on: August 13, 2015, 05:57:52 PM »
Hello Manuel,

Probably, incorrect georeferencing? Are you using linear flight?
Best regards,
Alexey Pasumansky,
Agisoft LLC

Mfranquelo

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Re: Orthomosaic generation
« Reply #5 on: August 13, 2015, 06:08:46 PM »
It seems like the DEM building is causing this distortion and then the orthomosaic inherits the distortion because its generated from the DEM.

I've just been playing with a new DJI phantom professional. I shot around 233 photos following a more or less random pattern for testing purposes. The drone was manually controlled and I shot images manually as well.
I've tried using different coordinate systems but I guess its not dependant on that isn't it?

Why would the images be bad georeferrenced? I recall that the drone just detected 8 satellites so it might have wrong or innacurate GPS positions. Is the DEM building process using them in some way? I am pretty new to aerial imagery and GIS so I am a complete newbie  :-\

Manuel.