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Author Topic: Orthomosaic appears green  (Read 1469 times)

ulrichz94

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Orthomosaic appears green
« on: October 10, 2022, 12:17:57 PM »
I used Agisoft to align and process a set of old unreferenced orthoimages and produce on big orthomosaic from them. The workflow itself worked fine but the produced products (tie points, dense point cloud, orthomosaic) all appeard very dark (see attachment).

When importing the final orthomosaic into ArcGIS it appears green (see attachment). The original orthoimages had regular RGB-colors.
Has anyone an idea what happened here?

Alexey Pasumansky

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Re: Orthomosaic appears green
« Reply #1 on: October 10, 2022, 06:35:18 PM »
Hello ulrichz94,

What is the source data format (8-bit per channel, 16-bit per channel, 32-bit floating point)?

How does the orthomosaic looks in Metashape, if you adjust the brightness in Ortho view to fix the dark colors?
Best regards,
Alexey Pasumansky,
Agisoft LLC

ulrichz94

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Re: Orthomosaic appears green
« Reply #2 on: October 11, 2022, 08:29:03 AM »
Dear Alexey,
Thank you very much for your reply.

The original images are large 3-Band, 16-bit unsigned TIFF images. These are true color photos with a yellowish tinge (see attachment).

In Metashape the orthomosaic turns out to be non-color (black and white) when adjusting the brightness (see attachment).

Alexey Pasumansky

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Re: Orthomosaic appears green
« Reply #3 on: October 11, 2022, 12:58:55 PM »
Hello ulrichz94,

Please check that RGB bands are properly interpreted in Camera calibration dialog -> Bands tab or Raster Calculator -> Input Bands section in Transform tab.

If so, the output orthomosaic bands should be of same data type, providing that you are not using Raster Transformation option in the Export Orthomosaic dialog. I can also suggest to try disabling "save alpha channel" option when exporting the orthomosaic.

If it doesn't help and the problem persists, please send the PDF report exported from the processed project and low resolution orthomosaic export results (like 4000 x 4000 pix image) to support@agisoft.com.
Best regards,
Alexey Pasumansky,
Agisoft LLC

ulrichz94

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Re: Orthomosaic appears green
« Reply #4 on: October 12, 2022, 09:12:43 AM »
Hello Alexey,
Thanks for the advice with the Camera Calibration. It seems like the bands were not interpreted correctly (see attachment). How can I fix this? Do I need to reprocess the whole project?

Thanks for your help and kind regards,
Ulrich

Alexey Pasumansky

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Re: Orthomosaic appears green
« Reply #5 on: October 12, 2022, 12:27:16 PM »
Hello Ulrich,

Do you have the possibility in ArcGIS to specify, which channels should be used as Red, Green and Blue?

As a workaround, you can export the orthomosaic in False Colors representation, but it would lead to conversion to 8-bit RGB. In case it is not a problem for you, then you need to create three output channels in Raster Calculator dialog, set formulas as B1 / 65535, B2 / 65535 and B3 / 65535 (you can use smaller ration value in order to make the output brighter, but the same for all bands), in the Palette tab of Raster Calculator dialog select False Colors options and during the export enable Raster Transform -> Palette option.
Best regards,
Alexey Pasumansky,
Agisoft LLC

ulrichz94

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Re: Orthomosaic appears green
« Reply #6 on: October 13, 2022, 10:55:32 AM »
Dear Alexey,
thank you very much for your help.

I was able to export the orthomosaic with the correct colors using the Raster Calculator. I had to reduce the ration value drastically to 400 but then I got a fine looking image.

Thanks again and kind regards
Ulrich