Hey all,

I've finally had a chance to start messing around with the new 
PointCloudGenerator node. I'm hoping some of you with more experience in this 
area can help me with a couple of things that I don't quite understand…

The main question I have deals with point coverage. I have a test clip I'm 
using that is shot from a boat, looking onshore at some glacial ice, with rocky 
mountains in the background. I can get a lovely CameraTrack, thanks to all of 
the available points to track. The parallax is good as the boat moves up and 
down and goes slowly past and around the glacier ice. In the PointCloud 
Generator, I've tracked points and get a pretty good lock with points on the 
foreground ice and on the background rocks. However, I do not get full coverage 
of points in the shot. For example, the foreground ice is truncated on the left 
hand side at the beginning of the shot (the boat moves from left to right 
across the scene, so the footage moves from right to left). Also, as the boat 
bobs up and down, it reveals more truncated points at the top. I never lose 
coverage on the right of the frame, however. I can't tell what's happening on 
the bottom of the frame, since I am masking out the water that is there. I'm 
guessing that the lack of coverage on the left probably has to do with the fact 
that there are no prior frames to look at for parallax reference. But, still, a 
regular camera track seems to have more coverage. I can't quite wrap my head 
around this. Can anyone explain it to me? And, is there a way to do the 
analysis to get greater point cloud coverage…?

I watched the demo video that Steve Wright put together - 
https://vimeo.com/54931986 - and his mountains clip happens to be very similar 
to my test clip. Looking at his result, I can see that he is also getting the 
same sort of clipping - not getting complete coverage of his scene. So, maybe 
the rest has to be hand modeled after a mesh is generated? I mean, in order to 
do a projection on a mesh derived from the point cloud, you'd absolutely have 
to extend it. Is this always a manual process…?

Thanks for any help!

Rich


Rich Bobo
Senior VFX Compositor
Armstrong-White
http://armstrong-white.com/

Email:  [email protected]
Mobile:  (248) 840-2665
Web:  http://richbobo.com/

"I have long been of the opinion that if work were such a splendid thing the 
rich would have kept more of it for themselves."
- Bruce Grocott (1940 - )





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