I've noticed that after an initial registration using target spheres (I use 6 target spheres with a 3 target sphere over-lap), my registration report is "all in the green"; and the point clouds themselves seem nicely aligned with each other. However, if I start refining the registration by setting anti correspondence of target tensions with the highest distance errors, I've noticed at times that even while the distance errors trend downward (as desired); sometimes one or two scans seem to get way out of alignment. The first time I noticed this, one of my scans was off by over 2" from the rest; but by the time I finished getting the lowest distance error; it all seemed to come back together.
However, with my latest project, I noticed two of the scans (out of 26) would quickly go out of plane by around 3/8" after the second anti registration, and never improved by the time I went from a distance error of 0.357" to 0.044". Unfortunately due to the graphics in Scene, this wasn't obvious until I tried working with the point cloud in AutoCAD--which I use to take measurements with. I decided to delete the two offending scans, since I seemed to have enough overlap anyway. So far that seems to have helped. However, this process is very time consuming (the export process to RCP takes awhile); plus it's hard to check every nook and cranny of the point cloud (in a timely manner) to see if everything is truly aligning correctly.
Does anyone have any tips they could offer? Perhaps I should just be "happy" with initial registration reports; instead of trying to chase a perfectionist report that obviously doesn't correlate directly to tighter registrations between scans...
I've seen a couple similar threads from 4 years ago; but none of them seemed to offer a specific solution nor address the problem that I'm facing. I've seen some say they use target spheres initially followed by cloud to cloud.
I noticed that yankoch posted here: https://laserscanningforum.com/forum/vi ... 570#p51570
Perhaps this might help me, but I have no idea how to drag scans into C2C folders. I've got lots of experience using C2C in the past; but it seems to over-write any prior effort with registration target spheres first. Can anyone direct me to a tutorial on how to do this process?yankoch wrote:Then, when the target based registration is ok, we just drag the target based scans, keeping their position, into C2C folders, and we define them as the reference scans. Then we do C2C using these reference scans.
I'm hesitant to disable inclinometers for various scans (though it might be better than simply deleting them; assuming this helps); as I understand that by keeping inclinometer enabled during registration helps accuracy: a function of the inverse square law of 3D fields. Knowing what's truly vertical is very important for what I do as I measure how far out of plumb walls are.
Appreciate any help on this matter...
Thanks,
Steve