Thanks again for having developed ODM, being for me, the best open source platform for building UAV maps. However, as all platforms always need to be improved and I think I can help with this issue in concrete (in multispectral images). Currently the ODM does the multispectral mapping comparing between the different multispectral bands. I think here is the biggest flaw when trying to compare different bands in agricultural fields because it is very difficult to achieve a perfect overlay of different multispectral images. An example follows in the images below:
As shown above, you can conclude that it is really difficult to match the different images (different bands). So, in this case, my point of view was doing a full map in each band, i.e. a solo blue map, green, red, nir and rededge map (but before doing the five maps, I calibrate each image from micasense code to originate the reflectance image instead of dn image). The next two images are an example of a full map of each band (to simplify i just show two bands- green and blue):
As you can see, the maps are too dark. Thus I just applied a gamma correction:
Next I applied the next steps:
- Extract features with SIFT, SURF or ORB
- Find the Homography matrices between the 5 different bands maps
- Applied the Warp Perspective to overlay these maps.
The results now are these:
And the biggest improvement NDVI:
PS- the white points are due to the terrible ubuntu viewer
Besides that you can observe the improvement alignment:
Before (rgb map with zoom):
After (rgb map with zoom):
To finish I just want to say that I will clean my code and after I can share with all community Do you have a specific place to share?