Thanks, I will send the project today. It's around 100 GB currently.
One thing that I think is either causing this error, or is happening as a result of it, is that GCPs I add at the far end are being "blue flag" projected onto the initial photos several miles away. This prevents the GCPs from aligning with their real-world locations. Going through the photos and manually clearing the marker placement fixed it once, but then when I add more GCPs it happens again. By "fix" I mean I optimized the cameras and the tie points aligned with the map as expected. But after aligning more photos, I can't get it to line up anymore. Also, I can't find a way to batch clear marker projections, so I have to go through dozens or hundreds of photos and individually clear the projections.
You can see in the attached image 1 how there are only two real GCPs (point 4 and point 33) and the rest are projected from locations throughout the corridor. The blue flags are new ones, and all the white flags are ones I cleared previously.
Image 2 shows the top-down view of the photos I've aligned so far. The project is an 18-mile stretch of road captured in a 24 fps video. Right now I am stitching the images from the Eastbound capture.
The highlighted line shows the actual road, and all of the GCP coordinates correspond to points along that road. The coordinates were taken from Google Maps and the accuracy is set to 10m.
As you can see, the model wants to wrap around on itself despite Metashape doing a fairly good job of sticking to the curvature of the bends. I think this is happening because of the GCPs, specifically the far-right GCPs being "blue flag" projected onto the far-left images. Although, before adding any GCPs it was also showing signs of warping.
I've been aligning a batch of photos, adding GCPs, optimizing, adding more photos, aligning, adding GCPs, optimizing, repeat. If this is the wrong method, let me know and I'll adjust my workflow.
I calibrated the lens in Metashape using the chessboard, but I did not indicate the pixel size and focal length (this is because the camera app I used produces 4000x3000 video whereas the stills with EXIF information are slightly larger, and I did not want to risk inputting the wrong values. Does this make any difference?)
The screenshot of my reference pane with GCP coordinates has 0.1 as the accuracy, but the accuracy has been set to 10.0 up until this point and my problem occurred with that setting (I am trying different things to see what might fix this).