Pcwrite to make sss pointcloud

[Korhon]

Hi!

I was wondering if its possible to use pcwrite to write out a pointcloud that Houdini`s SSS shaders can use?

Im guessing i need to write a ptarea atribute like the sss_scatter Sop does, but i dont know how to that with pcwrite

Anyone that know how to do this?

Thanks!

[bhaveshpandey]

i'm sorry, i did not quite understand the question..

do you intend to write the Point Cloud data to disk?

(if yes..you can write it out with a normal File SOP with a .pc extension while saving....you can access these in VEX using the pointcloudopen vop)

I guess ptarea is a promoted attribute..you basically calculate area of a primitive (or your geometry) and then promote it...you can dive into the SSS Scatter node to see how its done.

hope this helps.

[Korhon]

Thanks for the reply!!

Yes i want to write pointcloud to disk. But i want to do it with a shader. ( the pcwrite node)

That way its easier to write pointclouds that can be displaced.

The scatter sop uses the measure node to create the area atribute it seem.

And i dont know how to do this in vops

Anyone?

[symek]

Thanks for the reply!!

Yes i want to write pointcloud to disk. But i want to do it with a shader. ( the pcwrite node)

That way its easier to write pointclouds that can be displaced.

The scatter sop uses the measure node to create the area atribute it seem.

And i dont know how to do this in vops

Anyone?

There is a function in VEX called area() (and corresponding Shading Area VOP), which does similar thing. Few questions arise though:

a) Does ScatterSOP, which computes ptarea for SSS Scater by averaging distance to neighboring points, takes a power of it or not?

SSS Scatter seems to weight ptarea with average area for a whole geometry (ptarea * (ptarea/total_ptarea) ). How to achieve similar thing in vex?

c) Quite possible you don't want to save every micro-polygon in point cloud, how to sum up areas of points left behind (not saved in point cloud)?

[ykcosmo]

I have the same question too....

I used to use prman to make sss with point cloud or brick map, wanna turn to mantra to have a try. Maybe the above questions all from prman way to mantra?

[Korhon]

Thanks Symek!!

I will look into the Shading Area Vop, and see if i can make some use of it

To get a pointcloud that don`t contains every micropolygon point i was hoping there was a way to control the shadingrate with the shader.