Hello Metashape Fellows,
I'm bringing again to the discussion the processing of images captured with the FLIR Duo R.
There have been a number of reports from other users who were able to obtain thermal orthomosaics, and from others who were not so lucky. However, as far as I know, there is no generalized procedure for doing this.
Presently is possible to obtain a separate RGB and Thermal ortomosaics. The main problem is to get both co-registered.
** Some time ago I've shared here a procedure where RGB images (cut to size 1440x1080) were processed first, and then replaced in the project with the thermal images (resized to 1440x1080). It was not perfect, it had clear misalignments, but it already gave an idea of the thermal panorama of the covered area. Presently I don't recommend this option..
** A more consistent procedure is to merge the RGB images with the thermal images (both 1440x1080), creating a single multi-spectral RGBT image. This article explains and demonstrates this procedure:
https://www.mdpi.com/2072-4292/11/11/1365.
I made several attempts in this way, the procedure surely becomes more seamless but still misses co-registration between bands. The RGB orthomosaic appears correctly but the Thermal shows evident stretching misalignments. So, improvements must be done.
** Currently, as I've mentioned, processing only thermal images produces good results. This is already a big step forward.
** Lately, using the multi-camera system processing approach, my expectation would be that this process could work with the FLIR Duo R. Unfortunately, the results are still not satisfactory: the thermal orthomosaic always presents stretching misalignments.
In comparison, I did several processing with sample images captured with Micasense Altum (
https://micasense.com/sample-data-altum) - 5 bands + Thermal - always with good results. To try to match the processing conditions to the FLIR Duo R, I removed all the orientation information and characteristics of the sensors that are registered in the EXIF of the Altum images. Even so, the results were good. The thermal orthomosaic stitching is good and and the co-registration between the multi-spectral bands and the thermal band (orthomosaics) loses very little quality.
I'm attaching some results from my processing with the FLIR Duo R and I'm providing the image dataset in use, asking for collaboration of the interested users and Metashape moderators, for a proper solution.
Image dataset RGB + Thermal:
https://meocloud.pt/link/453b2b19-5475-443f-9106-96745c93b105/FLIR-Duo-R/