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Author Topic: Sparse cloud not updated after incremental alignment  (Read 1556 times)

beldridg

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Sparse cloud not updated after incremental alignment
« on: November 19, 2022, 06:00:27 PM »
Hi,

I have a large wreck project I'm working on in phases. I made my fifth dive yesterday and took another set of photos.

I made a low accuracy alignment of JUST the photos from the 5th dive and it worked with 1486 cameras out of 1486 getting aligned  (I've attached a screenshot Dive5-Only) with the workspace.

For my next step, I opened up the existing model that had the results of the previous four dives aligned (4951 cameras out of 4955). I've attached a screenshot Dive4 with that workspace.

You can see the similar areas on the starboard side bow and some of the bridge area.

I then added the photos from Dive 5 into the existing photos from Dive 4->1 and ran a Medium accuracy alignment which took about 6 hours (Note that I had used Tools->Reduce Overlap with 5 cameras per point in order to expedite the alignment of the new photos.

The result was that 6418 photos out of 6441 aligned, BUT the sparse cloud did not reflect the addition of the new photos. I've attached a third screenshot named Dive5-combined.

As far as I can tell, it doesn't include any of the new photos. I've tried saving, closing, re-opening, etc. all to no avail. Given the amount of processing time it would take to re-align all 6441 photos (2+ days I think), I wanted to check in here first.

Any ideas?

Thanks,

- brett

beldridg

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Re: Sparse cloud not updated after incremental alignment
« Reply #1 on: November 21, 2022, 03:43:28 AM »
A quick update on this. I basically figured out what was going on. After "Dive 4" all the photos had aligned; however, a whole slew of them were aligned in a "rats nest" of photos.

Basically, it was a "butterfly effect" where two pictures aligned but the angle was off and then it spiraled in on itself. The photos for the new dive aligned with the photos in that rats nest and so it just got worse.

I finally figured it out and corrected it but it was painful and I learned my lesson. Always do a sanity check to see if things are correct on the sparse model even if they are aligned.

- brett

SimonBrown

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Re: Sparse cloud not updated after incremental alignment
« Reply #2 on: November 21, 2022, 11:52:37 AM »
6000 images is not so large dataset to align - what settings are you using and what format/size of images are being used?
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beldridg

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Re: Sparse cloud not updated after incremental alignment
« Reply #3 on: November 26, 2022, 06:37:05 AM »
6000 images is not so large dataset to align - what settings are you using and what format/size of images are being used?

Hi Simon,

They are "out-of-camera" JPG from a Sony a6400 so they are 16MB or so each (dimensions 6000px x 4000px with a resolution of 350dpi x 350dpi).

My settings are Key Point Limit of 40,000 and a Tie Point Limit of 10,000. Generic preselection = No, Reference preselection = No, Exclude stationary tie points = Yes, Guided image matching = No, Adaptive camera model fitting = No.


Thanks for any tips or guidance.

- brett