[Sidefx-houdini-list] Imitating Perceptual field of view using Point clouds..

bhavesh pandey pandeybhavesh at gmail.com
Thu Jan 27 20:58:05 EST 2011

Hi people..I'm trying to implement a flocking system in houdini using point
clouds in SOP Solver..Although I can compare the angles of the points and
thus simulate something similar to a field of view, I want to optimize my
system by using Point Clouds instead of doing a one to one comparison with
all the points in the scene. Also I had setup a while loop with the point
cloud iterate node to manually filter them out (within the loop) but I
couldn't really think of any clever ways to get the average of any arbitrary
imported point cloud attribute..(which I would need to calculate Perceived
average position of each point in space)

To test the cone angle option in the PCOpen node I did a small test. I took
2 points and set their normals to their respective normalized positions so
the points had Normal attribute on them. After this I used a transform node
(both nodes had recompute normals turned off) and moved around any one
arbitrary point (transform node was appended before the vopsop used for
calculations) but I dont feel Point cloud data is getting filtered out based
off the Cone Angle..
for instance:
according to the help card:

"Points with dot(N, Npoint) > cos(cone) will be queued, and unmatched points
will be rejected."

now since i had set position data as normals, the dot product of the
positions for this point (1.95327, 0.334443, 0.340146) and the nearest point
(-3.49418, 0, 1.43283) as indicated by the pcfilter (i'm just looking up for
1 point, so i guess the value would not be averaged out??) was  -6.337703
whereas Cos(cone = 90) = 0

I am not really able make sense out of it..I'm sure I'm missing something,
Could some one point me to the right direction??

The Point cloud open node should have some optimized solution for this
(filtering based off cone angle) which would help me optimize my VOP


Kind Regards,
Bhavesh Pandey.


More information about the Sidefx-houdini-list mailing list