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Hey Metashape,
I am still trying to understand exactly how the reference data that we can import to images is working during alignment. I am working with thermal infrared images that were taken from an aircraft during multiple passes over a wildfire. I am essentially trying to create an orthomosaic for each pass over the fire. Each of the passes occurs over the same position of the fire.
To start, let's say my general workflow is to import thermal images into a chunk, add inertial references to the images (lon, lat, alt, roll, pitch, yaw, and accuracies), and then run the image alignment with highest accuracy and sequential reference preselection, key point limit = 40,000 and tie point limit = 10,000. I noticed that I get some variable results such as: during the image alignment, it may align the images with the point cloud projected up in the air instead of on the basemap, so there is zero resolution when I go to create an orthomosaic, and I may have to rerun the alignment several times before it correctly aligns the images so it can build the mosaic. There are also times when I run the alignment and it works, but then I go to run the alignment with the same images and same reference data again and the images align, but are shifted in their projection. So I align a set of images and build an orthomosaic, then align the same images again with the same reference data and build another mosaic, but the second mosaic is shifted either west or east from the first one. I know there is going to be some error in the accuracy and precision when georeferencing, but I have to do a lot of re-alignments or deleting chunks and re-creating the chunks to get through several passes over the fire. I guess my question is, is it typical to see this type of variability or inconsistency when aligning the images?
Second is, how much weight is the reference data given when alining and projecting the images to build the mosaic? From my understanding metashape uses points across images to help align them and then kind of uses those points with the reference data to create the aligned end result, but does it give priority to the reference data to align the images and then make some corrections with the image points to achieve a final result? Or weight them equally more or less?
Sorry for the long questions, I am still just trying to understand exactly how the reference data is used with image points to align the images and eventually create an orthomosaic, and why I might get such variability in the alignment process or placement of the images in the orthomosaics.
Thanks again for the help,
Chris
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