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

Andrew D Lyons tstexture at gmail.com
Thu Jan 27 22:51:30 EST 2011

Have you thought of using POPs instead of DOPs?

The follow pop will help with flocking. That and the interact POP.

Take a look at the "Tiny.otl" on the Houdini Exchange for a more complex


On 27 January 2011 17:58, bhavesh pandey <pandeybhavesh at gmail.com> wrote:

> 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
> network.
> Thanks.
> --
> Kind Regards,
> Bhavesh Pandey.
> www.bhaveshpandey.blogspot.com
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Andrew D Lyons | Digital Artist | http://www.tstex.com

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