@CheeseAndJamSandwich
Your underwater work is interesting.
Are you using generic preselection? and what is your hardware? 2.5days for one big alignment seems to be too long. I would expect several hours of alignment time for ~25000 big photoset.
Yes. It's on by default, tho i did do some tests a long time ago and it was hilariously longer without it.
I have a big fat ThinkPad P51, from 2018... Sadly no desktop...
https://www.notebookcheck.net/Lenovo-ThinkPad-P51-Xeon-4K-Workstation-Review.229212.0.htmlI have bags of RAM in it, 64GB, but my jobs hardly use more than 20, perhaps 30GB.
But the old Xeon and the crappy old Quadro M2200 in it just don't compare with todays desktop HW... I continue to dream of course....
As my scans started off pretty erratic in their paths for the early scans, i have a lot of overlapping, areas scanned more than once... This turns out to make the alignment times go exponential.
My next test plan is to compare each of the individual scans, and delete the photos that cover the same areas, keeping the ones from a better scan... Perhaps when the water visibility was better... And deffo on the areas where the rocks/reef meets the sand... As you can go back the next day, and if the swell was big, the height of the sand might have risen, dropped a foot! Which causes horrible double layers in my mesh. With a bit of thinning out of the duplicated areas, i could probably knock a day off of the big alignment job.
Did you try decrease key point limit to e.g. just 20k?
Yes... BUT... I was getting holes in my model where the the data was week (shaded sides of rocks, etc)... But after hearing about 1.7.4 & 5's bad meshes, and downgrading, rerunning the mesh and the holes filling in nicely, i think it was that, rather than the reduced point limits... My current job is adding a 10th scan to an already aligned 9 scans, that was done with 40k, so this is 40k too... The alignment was obviously a lot, lot quicker, and in a few hours time I'll have the mesh/model to check...
I'll test 20k for a future big alignment.
What precision you need in the end?(pixels on texture per cm/m...or point cloud points per cm/m).
I don't need great accuracy at all... It's for printed off 300dpi maps on A4, A3, and perhaps some massive posters for the dive shops... Also video flight around the models, Sketchfab models (just using the free 100mb limit, which is actually enough, deffo enough for loading onto a phone!)
I'm not gonna be doing any high precision measurements or analysis from this data. But it has to look correct of course.
Luckily, using my two GoPros, the models have come out perfect, no dishing, no bananas, even over long drift scans, that might be 500m long... It all just comes out great. Getting these good results without anything special, much work is actually very, very convenient.
Part of this work is also supporting the coral reef rehabilitation efforts we have going on here too... So mapping out bubble sites and then monitoring growth of the coral frames we put down. So i might be doing more smaller scale scans, of 2m x 2m frames, of individual corals, etc... Then it could become increasingly important to get cm, mm accuracy, but i'd need the professional version to allow any dimensional analysis of these.
I could deffo do with some of the other Professional features like DEMs, etc, which naturally work great as dive site maps, but simply will never ever be able to afford the $3,500
Are you many times also orbiting around rocks when taking photos, or is everything mostly from top down?
Some of the site dictates the orbiting around the rocks, as they're literally house sized, 10m tall, wide... And in my earlier scans, i was zooming around all over the show, with little planning... But now i'm trying to do a lot more 'mowing of the lawn' scans, which are a lot, lot quicker at covering area... Though keeping straight UW is tough, even with a compass, and if the pass is long, then there's a chance track diverges from the previous pass' track, so you get an annoying scar of weak data... doh... Underwater, everything is more difficult.
If i was to redo the whole job of the big site I'm doing right now, i could probably do the same area in 6 dives instead of 10. Which would take a lot, lot less time to process, as there would be a lot less overlapping scans, which disastrously affect the alignment time.
I have 3 or 4 other sites i need to scan soon, and a couple of shipwrecks i have scans of... It's an awesome project to be doing, and learing MS has been a lot of fun... If only i had a 5950X and a 3090!!!
And last funny question: can you swim faster to better use 2s interval on GoPro? 
LOL I'm swimming as fast as i can!!!
I'm using my big long freediving fins/planks, but also have a sling tank, a whole extra AL80 tank on my side, as I'm scanning alone, so have to double up on everything for safety... So not the most streamlined underwater... Can't find a buddy that can keep up with me! (or that also has two cameras). Oh, and I'm chugging down both 200 bar, 11 ltr tanks, down to 30 bar, in 45 mins! My extra layer, kilos of 'bio-prene' might not be helping either... Though it keeps me warm.
The limited choice of interval is a real bummer actually... 3s would just make everything so much easier! I've requested it on GoPros forums, Basically just choose any value of seconds... but that's just a dream.
Topic: Processing a massive underwater photoset without GPS (Read 8500 times)
