Hi all.

I try to tune Subsurface in mantrasurface Houdini shader.

What i have (files attached):

1. static camera
2. deformed geometry
3. diffuse, specular, reflections - disabled (for understanding major problem)

I like sss that i can tune for static frames, but when i render animation - my SSS is flickered..

And i can't understand why, but flickering is occur on static geometry frames..

And i can't clear that by increasing sampling, or tracing parameters.

What wrong with mantrasurface shader? How can i get render w/o flickering ?

I'm confused.

today i try SSS on static object and i'm also get flickered SSS.

1. shadows disabled
2. geometry static
3. point clouds don't changed (all points is stay on their places from frame to frame)
4. i use simple points light (instead of area that i have used before)


Why SSS is flickered? Does Houdini have a worked SSS solution?
May be this is a bug?

- - -
Houdini 1.11.92 on Ubuntu 10.04 x64

Hm.. looks like at this moment Houdini 11.1 can not produce hight quality SSS for production tasks.

1. AXIS SSS toolkit from Exchange library give me only black frames with alpha.
2. All SSS solutions produce flickered results and any parameters on shaders or mantra can't clean that.

This look so strange.. May be i'm wrong, but mental ray and vray going to realtime.

..but i can't create clean SSS in mantra. I'm right ?

You can eliminate/reduce flickering.

The problem is that you are using a different point cloud for each frame. This causes flickering.

To fix the problem, generate the point cloud on frame 1 and then use the same point cloud for the entire animation. This may sound strange given that the object is deforming but the point cloud doesn't store point positions – it stores parametric surface coordinates. These coordinates are re-mapped onto the surface before each frame. Houdini's SSS was specifically designed to handle deforming meshes.

To summarize:

1) Go to frame 1.
2) Set the point cloud file to “$HIP/points.pc” (note that there is no “$F”).
3) Set the point cloud mode to “Write to File”.
4) Render the first frame.
5) Change the point cloud mode to “Read from File”.
6) Render your animation.

I attached my results. Good luck!

I'm sorry I absolutly need to “up” this topic.

How can I generate a photon map for moving objects ? I mean for a sequence. Because I have a lot (I mean a LOT) of flickering in my render, with pretty high sampling, and as ikerr said “The problem is that you are using a different point cloud for each frame. This causes flickering.
”… How can I avoid this ?


Thanks !

I should create an other topic…

Or should I render separately elements, the ones who are moving on a separate layer, and the still ones on another ? But how can I have photon on the moving ones without having flickering ?