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Prman Point Clouds Quering Points?


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Does anyone know how one can query information of the baked points in a point cloud?

ptclouds.jpg

From the picture say I am using an illumination loop on point P and I need to calculate the distance from that point to the pointclouds points Pc over the distance D.

Does anyone know what prman function I need to use to get that information?

I know where is a filter radius in the texture3d function, but it doesnt give u the distance between the 2 points...

PS: btw I am trying to implement Mario's sss code into a rsl code...

Thanks in advance

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Hi there,

I'm only now starting to get back to PRMan after being away from it for about 2 yrs., so I'm not up on all the latest-greatest features (including point clouds and brick maps). But after reading app-notes #39 and the updated #37, it would seem that the level of control that the pcunshaded()/pciterate() functions give you in VEX is just not possible using brick maps.

The good news is that they've added the ptfilter program, which includes an implementation of Jensen's "Rapid Hierarchical etc" paper (i.e: subsurface scattering) without you needing to code it. So you just select among the predefined materials or pass it all the parameters and you're done... Of course, whether these parameters are intuitive or not is a different story, and having to experiment with material properties via a static pre-process pass could get, uhm, "tedious", but it's there...

I guess you could use some form of gather() to emulate the point scattering, and then use bake3d() to both store the calculations and later look them up (as interpolated values). Don't expect this method (which incidentally I believe was the original method before brick maps showed up) to be a speed demon though.

Maybe someone who's more up-to-date with PRMan can offer some better suggestions...

Cheers.

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Does anyone know how one can query information of the baked points in a point cloud?

ptclouds.jpg

From the picture say I am using an illumination loop on point P and I need to calculate the distance from that point to the pointclouds points Pc over the distance D.

Does anyone know what prman function I need to use to get that information?

I know where is a filter radius in the texture3d function, but it doesnt give u the distance between the 2 points...

PS: btw I am trying to implement Mario's sss code into a rsl code...

Thanks in advance

21945[/snapback]

I'm pretty sure you're looking at having to write a custom shadeop using the PRMan API ... sorry.

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