Agisoft Metashape

Agisoft Metashape => Bug Reports => Topic started by: andyroo on February 19, 2022, 01:58:30 AM

Title: 1.8.1 - gap in initial alignment w/ precise positions, double-pass, 90% overlap
Post by: andyroo on February 19, 2022, 01:58:30 AM
I had an odd thing happen on my first alignment w/ 1.8.1 -

All but 54 (of ~2000) cameras aligned, and the unaligned cameras were part of a double pass on a shoreline with good features, good GPS positions (PPP with camera arms input), and no distinguishable difference from their neighbors, right in the middle of a gently curving shoreline.

Since I kept the keypoints, I was able to select only the unaligned images and "align selected" and they aligned perfectly with the others in just a few minutes, but the apparently random dropout makes it hard for me to trust an alignment workflow in any automated fashion.

Align settings were (from dropdown, not batch) - Accuracy High, Generic Preselection, Reference Preselection/Source, 60,000 keypoints, 0 tie points exclude stationary tie points checked, guided image matching off,  Adaptive fitting off.

I attached the logfile (zipped because size) for the alignment in case it's useful.

Camera is Nikon D810, images are JPGs derived from RAW with Adobe Camera RAW at full quality, no chroma subsampling, Adobe Camera Standard color profile and no other tweaks. I have not seen this issue in 1.6.9 or 1.7.5 (didn't play with other intermediate versions).

/andy
Title: Re: 1.8.1 - gap in initial alignment w/ precise positions, double-pass, 90% overlap
Post by: Paulo on February 19, 2022, 02:37:42 AM
Hi andyroo,

looking at your log it seems these 54 images form a subblock whose estimated camera parameters are wildly different from other sublocks. For example in last iteration, the 54 images get an estimated f of some 91 000 pixels compared to average f of around 8 400 pixels. See extract from log:
Quote
2022-02-18 14:03:18 block: 1 sensors, 54 cameras, 200690 points, 883658 projections
2022-02-18 14:03:18 block_sensors: 0.000816345 MB (0.000816345 MB allocated)
2022-02-18 14:03:18 block_cameras: 0.0210114 MB (0.0210114 MB allocated)
2022-02-18 14:03:18 block_points: 9.18686 MB (9.49319 MB allocated)
2022-02-18 14:03:18 block_tracks: 0.765572 MB (0.765572 MB allocated)
2022-02-18 14:03:18 block_obs: 20.2253 MB (20.2253 MB allocated)
2022-02-18 14:03:18 block_ofs: 1.53115 MB (1.53115 MB allocated)
2022-02-18 14:03:18 block_fre: 0.228493 MB (0.228493 MB allocated)
2022-02-18 14:03:18 adding 196712 points, 0 far (12.272 threshold), 19349 inaccurate, 0 invisible, 0 weak
2022-02-18 14:03:18 adjusting: xxxxxxxxxxxxxxxxxxxx 2.04162 -> 2.0359
2022-02-18 14:03:21 adding 19390 points, 22 far (12.272 threshold), 19289 inaccurate, 0 invisible, 0 weak
2022-02-18 14:03:22 adjusting: xxxxxxxxxxxxxxxxxxxx 2.03732 -> 2.03292
2022-02-18 14:03:25 adding 19331 points, 9 far (12.272 threshold), 19225 inaccurate, 0 invisible, 0 weak
2022-02-18 14:03:25 adjusting: xxxxxxxxxxxxxxxxxxxx 2.03546 -> 2.03183
2022-02-18 14:03:29 adding 19266 points, 5 far (12.272 threshold), 19107 inaccurate, 0 invisible, 0 weak
2022-02-18 14:03:29 adjusting: xxxxxxxxxxxxxxxxxxxx 2.03481 -> 2.03192
2022-02-18 14:03:32 adding 19140 points, 6 far (12.272 threshold), 19028 inaccurate, 0 invisible, 0 weak
2022-02-18 14:03:32 adjusting: xxxxxxxxxxxxxxxxxxxx 2.03387 -> 2.03165
2022-02-18 14:03:36 adding 19064 points, 12 far (12.272 threshold), 18941 inaccurate, 0 invisible, 0 weak
2022-02-18 14:03:36 optimized in 18.021 seconds
2022-02-18 14:03:36 f 91454.5, cx 0, cy 0, k1 -4.2249, k2 1017.47, k3 0
2022-02-18 14:03:36 adjusting: xxxxxxxxxxxxxxxxxxxx 2.03417 -> 2.03222

So I guess  this is why subblock cannot be merged with other blocks.. I am sure that Agisoft support will be able to give you more insight

PS. by the way what lens was used for survey, fixed focal length or zoom lens?
Title: Re: 1.8.1 - gap in initial alignment w/ precise positions, double-pass, 90% overlap
Post by: andyroo on February 22, 2022, 07:42:11 PM
Hi Paulo,

Thanks for taking the time to look at my log, and good catch! I didn't catch that, and it gives me a good idea on where to look in the future.

The lens is fixed focal length - Voigtlander Ultron 40mm f2 SL II.

I wonder if the oblique (~45°) camera angle is a factor in that wild initial estimate - I periodically put in an estimated capture distance to try to help the reference/source preselection (we have PPP positions on all/most of the images), but from reading the manual, and from conversations with Alexey, I don't think that really helps unless I also have YPR, which I don't.

Also this is a good reminder to initialize with the adjusted values from the previous flight. That probably would've helped.

Andy