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Multi-spectral images already registered to colour - do I need to stitch all of them with sep control points?

I’m working on a project where we have images with about 60-80% overlap depending on acquisition conditions, but here’s the thing:  We don’t have geo data in the EXIF.  None period.

Several cameras though, and each of the monochrome images are registered perfectly against the colour image.  I believe if I can use the control points from the colour set of images for all the monochrome sets I’ll have perfect stitch jobs across all bands.  I found another software solution to do this but I really would like to have several of our workstations on Pix4D.  Is it possible to re-use control points across registered images so they all have the exact same stitch job?

Thank you so very much in advance to anybody who takes the time to reply!

Dear Josh,

This will depend on how perfectly aligned the monochrome images are aligned to the color images.

  • If the images correspond to different bands of the same image (for example, multipage tiff), so the images align perfectly on top of each other and were taken from the same position at the same time, then you can adjust the band weights to use only the band with the color images. See this page on how to edit the weights

https://support.pix4d.com/hc/en-us/articles/206726203

-If the images do not correspond to different bands (for example if they were taken by different cameras, or are not synchronized), then all images will need to calibrate, as they need to be positioned with respect to each other. What you can do is to put images from different cameras in different image groups (this is done automatically if the exif data is different). It is a good idea to check that images were grouped correctly if you have two cameras with the same camera model. See the following page for more about image groups

https://support.pix4d.com/hc/en-us/articles/202557949-Menu-Project-Image-Properties-Editor-Images-Table#label3

To summarize: yes it is possible to use just one set of images to calibrate the project, but only if the different images correspond to different bands of the same camera (same position, same triggering time). If this is not the case, the slight difference in time/position would create errors.

Best regards,

 

Thank you for the quick response.  Our images are perfectly aligned (preprocessed via OpenCV, although each does come from different cameras, our monochrome images are pixel-to-pixel aligned with our colour).  As such, it was a shame to stitch each band with different control points since control points from the RGB colour one would do for the entire set of images with great results, guaranteed.

The slight difference in time / position you mention doesn’t exist in our case even though the images are from different cameras thanks to our OpenCV preprocessor.

It seems that Band Configuration in Image Properties Editor accomplishes what we need if I’m not mistaken, then?

Dear Josh,

Yes, it seems that in your case, the band configuration editor is exactly what you would need. All of the bands will be calibrated by using only the tie points from one band (if all the weight is put on this band). You will then produce 1 DSM, but one reflectance map per band. The reflectance maps will therefore be perfectly aligned. 

Best regards,