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Author Topic: Raster Calculator - blank output for False Colors Pallette  (Read 4241 times)

wojtas

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Hello,
I have set of images from Parrot Sequoia (Green, Red, Red Edge and NIR bands). I use Raster Calculator to make NDVI index with no problem.
However, there is some problem or I am doing something wrong while trying to make False Color Pallete for color infrared CIR orthomosaic.
It seems like every time the output orthomosaic in the Ortho View is blank.
In raster calculator I take input bands and set the output bands with no math formula (no transform), then I go to Pallete window and set False Colors setting as: Red=NIR band, Green=Red band, Blue=Green band. No matter what combination I do, the output is always blank.
Can someone give me suggestion what I am doing wrong?
Please see attached screenshots.
Greetings

Paulo

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Re: Raster Calculator - blank output for False Colors Pallette
« Reply #1 on: May 20, 2019, 04:46:27 PM »
Hello Wotjas,

it seems the required bands for CIR composition have to be normalized to 1 ( i.e. dividing by 65535) before using them in raster calculator...

see attached screen capture...
Best Regards,
Paul Pelletier,
Surveyor

wojtas

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Re: Raster Calculator - blank output for False Colors Pallette
« Reply #2 on: May 24, 2019, 11:12:06 AM »
Thank you Paulo, everything works great now :)
Greetings!

BTW. Can you explain me why it is 65535, where does it come from? I guess its 256 x 256 = 65536 - 1 but I can not see connection between this number and photos resolution (which is 8, 10 or 12 bit)
« Last Edit: May 24, 2019, 11:17:18 AM by wojtas »

Paulo

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Re: Raster Calculator - blank output for False Colors Pallette
« Reply #3 on: May 24, 2019, 03:11:13 PM »
I think that the image bands are stored in 16 bit unsigned (ie values 0 to 65535)
« Last Edit: May 24, 2019, 03:13:29 PM by Paulo »
Best Regards,
Paul Pelletier,
Surveyor

Alexey Pasumansky

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Re: Raster Calculator - blank output for False Colors Pallette
« Reply #4 on: May 28, 2019, 07:52:53 PM »
Hello wojtas,

Please check "exporting results" section in the related tutorial:
https://agisoft.freshdesk.com/support/solutions/articles/31000148780-micasense-rededge-mx-processing-workflow-including-reflectance-calibration-in-agisoft-metashape-pro

The input MicaSense images are in 16-bit format and by default the output format is the same. If reflectance calibration is applied, the middle of 16-bit range would correspond to 100% reflectance value.
Best regards,
Alexey Pasumansky,
Agisoft LLC