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Author Topic: Multispectral and RGB cameras workflow  (Read 2222 times)

Alexandra Morgacheva

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Multispectral and RGB cameras workflow
« on: December 10, 2021, 01:47:05 PM »
Hello!
The section of the forest was filmed with Sony ILCE-6000 and MicaSense RedEdge-M cameras. The cameras were located on the same fixed-wing UAV, but the multispectral and RGB images are not synchronized, the resolution of the cameras is also different.
I need to build a dense point cloud and orthomosaic for both RGB and multispectral data. I tried to build two separate projects for the cameras, but the final data has a shift of several meters. What is the correct workflow for my problem? I want to have information about a certain tree (the coordinates of the crown are known) both in rgb and in multispectral form.
Thank you!

jrp

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Re: Multispectral and RGB cameras workflow
« Reply #1 on: December 18, 2021, 12:26:05 PM »
Disclaimer: I've never worked with drone data, though hope to at some point. I work with very diferent matierial.

If you have known coordinates, does that mean you have Ground Control Points?

I would likely try to get the 2 halfs of the project as separate chunks in the same project, then align the chunks using either: GCPs, automatic chunk alignment , or create manual control points if you can find some.

nprokofyev

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Re: Multispectral and RGB cameras workflow
« Reply #2 on: December 27, 2021, 04:20:28 PM »
Hello!
The section of the forest was filmed with Sony ILCE-6000 and MicaSense RedEdge-M cameras. The cameras were located on the same fixed-wing UAV, but the multispectral and RGB images are not synchronized, the resolution of the cameras is also different.
I need to build a dense point cloud and orthomosaic for both RGB and multispectral data. I tried to build two separate projects for the cameras, but the final data has a shift of several meters. What is the correct workflow for my problem? I want to have information about a certain tree (the coordinates of the crown are known) both in rgb and in multispectral form.
Thank you!

Hi Alexandra,
First of all, you can use RGB data from Rededge-M. However, a6000 data must be significantly more detailed.

1. I'd suggest aligning in a single chunk. This is the way to align both sets "pixel-to-pixel". There could be some issues with camera positions, so check reference tab after aligning before going on.
2. After successful alignment, create a copy of chunk.
3. I assume a6000 GSD is better, so build Dense cloud based on a6000's photos. In other words, disable all images captured by Rededge and build Dense cloud.
4. DEM/DTM as usual.
5. Do RGB orho as usual. Copy it when it's done.
6. Now activate multispectral images, disable a6000's images, do Reflectance calibration  and Build ortho again.