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Author Topic: Building texture from Orthomosaic  (Read 1821 times)

pbourke

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Building texture from Orthomosaic
« on: July 07, 2021, 05:25:25 AM »
I have a point cloud and orthomosaic image in the same coordinate system.
I can build a mesh from the point cloud.
Is it possible the create textures for my mesh from the orthomosaic?
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« Last Edit: July 07, 2021, 05:40:16 AM by pbourke »
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pbourke

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Re: Building texture from Orthomosaic
« Reply #1 on: July 07, 2021, 06:11:41 AM »
Related to this. Once I have my mesh (which is lower resolution than my point cloud) why can't I derive a texture image from the dense point cloud colours. I only seem to have the option of deriving it from the mesh vertex colours.
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Alexey Pasumansky

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Re: Building texture from Orthomosaic
« Reply #2 on: July 07, 2021, 06:53:50 PM »
Hello Paul,

You can use the following workaround: calculate mesh vertex colors from the dense point cloud or orthomosaic (via Tools Menu -> Mesh -> Colorize Vertices command) and then bake the mesh vertex colors to the texture using 3D model source option instead of Images in the Build texture dialog.
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James

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Re: Building texture from Orthomosaic
« Reply #3 on: July 07, 2021, 10:45:50 PM »
Is it possible the create textures for my mesh from the orthomosaic?
What I've done recently is generate my texture using orthophoto mapping mode, and then use photoshop to open the texture file and replace it with my orthomosaic.

It may have been a happy accident that the orthophoto mapping uv map was perfectly aligned with my surface (which was perfectly flat in this case) and thus trivial to replace it with the orthomosaic (just a bit of rotation needed).

I hadn't really given it much thought until now! I guess if it hadn't been so well aligned then probably the perspective warp tool in photoshop would have got me out of trouble.

You can also build texture at low resolution and then upscale in photoshop to substitute a higher resolution orthomosaic.

I don't fully understand why the texture and orthomosaic were so vastly different in appearance though. The 'texture' had a nicer general appearance, but suffered with some terrible and weird artefacts on zooming in. The orthomosaic looked pretty nasty zoomed out, but zooming in the details were all there which was the main thing.

This was a large metallic 'sculpted' panel photographed close up, with flash, using the wrong focal length and not enough overlap, so metashape did well to get anything usable. The well known competition couldn't even align the images.

pbourke

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Re: Building texture from Orthomosaic
« Reply #4 on: July 08, 2021, 01:12:52 PM »
Alexey, to your suggestion, that is what I believe I have done so far. Won't that approach only give me a texture at the resolution of the mesh vertices.
As it happens my point cloud, and orthotif image, are orders of magnitude higher resolution than any mesh I could contemplate building.
Or have I misunderstood?
« Last Edit: July 08, 2021, 01:16:23 PM by pbourke »
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