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theotheo

XYZ As Rgb in Cop from PointCloud.

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Hi Houdini peeps,

I've given up on autodesk and 3dsmax after 10 years of using it, and finally embracing Houdini.

Being fairly new to it Im trying to create a vex operator in vops that lets me read a pointcloud file, and outputs the position data (P) for each point and plots it as a pixel in a vex cop generator. So for each pixel the index of the pcloud iterates thru one point. Im guessing I need a if statement for the X coordinate of the image that if x<width then y+1 sort of speak.

I can't find many examples on vex cops and point clouds, and the ones I have doesn't seem to work. (atleast not for me)

Does this make any sense? As said, Im not sure what functions to use as Im new to Houdini and vex/vops and would really appreciate some tips/pointers.

Thanks!

-theo

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Hi Houdini peeps,

I've given up on autodesk and 3dsmax after 10 years of using it, and finally embracing Houdini.

Being fairly new to it Im trying to create a vex operator in vops that lets me read a pointcloud file, and outputs the position data (P) for each point and plots it as a pixel in a vex cop generator. So for each pixel the index of the pcloud iterates thru one point. Im guessing I need a if statement for the X coordinate of the image that if x<width then y+1 sort of speak.

I can't find many examples on vex cops and point clouds, and the ones I have doesn't seem to work. (atleast not for me)

Does this make any sense? As said, Im not sure what functions to use as Im new to Houdini and vex/vops and would really appreciate some tips/pointers.

Thanks!

-theo

How do you want to map 3d points onto 2d space image? With Uvs, bounding box? If not, points will be most probably unordered in respect to pixels, so it won't have much sense using ptnum. On the other hand rendering P in UV space as rgb in Mantra does exactly what you're asking: xyz in rgb pixels on a flat image, so using cops is not necessary. Also point could won't deal well with indexing points by its numbers, it can do well with points based on its proximity position. Can you describe a bigger picture? Maybe there is other way for doing what you're after?

hth.

skk.

btw I think in this material (not sure though) there is an example of using point cloud in cops.

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Hi Symek, thanks for getting back to me so quickly.

I've seend the example but I keep getting errors, so I'm not sure whats wrong with it/me :)

Basically its a particle system with px/py/pz and id attributes in a pcloud. (doesnt have to be, I just thought that it was easier with a particle system rendered out as apcloud)

The total particle index is the number of pixels needed to be written to sceen space, and every pixel has RGB mapped from px,py,pz. So basically you end up with a noisy looking image consiting of point data. But I don't want to limit it to just P, maybe add a velocty layer etc later.

I basically want to use houdini simulations to drive fusion particles in comp, and the comp side of things I have covered as Ive done something "similar" before.

I hope It made more sense this time :)

-theo

Edited by theotheo

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