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Author Topic: Point Cloud from RGBI images misses NIR channel in LAZ export  (Read 5945 times)

Ole Wegen

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Hello,

I'm creating a model from RGBI images, sampling a point cloud from the mesh, and exporting the point cloud in LAZ format.
When importing the images, the NIR channel is not correctly detected, therefore, I set it manually this way:

Code: [Select]
for sensor in Metashape.app.document.chunk.sensors:
    sensor.bands = "Red", "Green", "Blue", "NIR"

This works and the resulting point cloud has a channel for the NIR band, which I can confirm by switching the primary channel of the chunk to NIR.
When I export this point cloud as .ply or .xyz, the NIR channel gets exported as well, but if I export the point cloud as .laz file, it gets saved in version 1.2 format 2, which does not support the NIR channel.
I tried to explicitly set the name of the bands for the point cloud before exporting it:
Code: [Select]
chunk.point_cloud.bands = ["Red", "Green", "Blue", "NIR"]However, this did not fix the issue.
What could be the problem here?

Ole Wegen

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Re: Point Cloud from RGBI images misses NIR channel in LAZ export
« Reply #1 on: July 12, 2024, 04:12:25 PM »
Update:
After speaking with the support, the solution seems to be to colorize the point cloud using the original images: Tool -> Point Cloud -> Colorize Point Cloud (as also stated in this post: https://www.agisoft.com/forum/index.php?topic=14975.msg65627#msg65627).

After this, the point cloud could be exported to LAS version 1.4 format 8, however, only when using the Python API. An export via the GUI did not work.
So it seems a bit counterintuitive, but you have to re-colorize the point cloud, even if the point cloud already has colors from the textures of the sampled model (that are exported correctly to other formats than LAS).

As the colors from the colorization via images are slightly inferior in quality compared to the colors from the texture, I will probably just export the point cloud to a text file and convert it to LAS using some other tool.


Alexey Pasumansky

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Re: Point Cloud from RGBI images misses NIR channel in LAZ export
« Reply #2 on: July 12, 2024, 08:45:48 PM »
Hello Ole,

In the version 2.1.3 there will be a fix for the origin of the problem that you have reported:
- information about presence of NIR band will be kept for the texture,
- sample points operation (building point cloud from the textured model source) will also preserve information about NIR band.
Best regards,
Alexey Pasumansky,
Agisoft LLC