RenderMan and Ambient Occlusion

[barad_dur]

Howdy,

I have searched forums far and wide and have not found an answer to running AO from RMan in H10. It all seemed to be how to get RMan to work at all in H. Mine does work as I have set the environment. Does anyone have any information on how to run a simple Ambient Occlusion in RMan from H10? Any help would be appreciated. Thank you.

David

[Pazuzu]

I recomend that you visit those sites www.fundza.com, www.alan-warren.com, are very usefull; and the answer for the implementation of ambient occlusion are there. By default houdini ships with the function in the form of a node in VOPs, but if you don't find an especific function you can use the inline_VOP, yesterday i had implemented a point cloud base SSS from the prman docs, is very easy with the great tools that houdini give to us in VOPs.

Edited December 3, 2009 by Pazuzu

[barad_dur]

Pazuzu,

Thank you for the Alan-Warren reference. I did already know about the Fundza site. I think I know what my problem is: I don't know enough about RMan in general to wad a very small shotgun and while I feel comfortable in the Houdini context it is becoming obvious that there is a whole set of tools I am not aware of that I would need to be able to work effectively with RMan. I also seem to be stricken with the need to to be able to learn RMan from within the Houdini environment but this may be hindering me. You see, when someone says AOV . . . I get dazed. Easy enough to fix: Google AOV and come up with Arbitrary Output Variable - AH HA! now we are getting somewhere. And then I get examples of how to write that code and inevitably "Cutter" comes up. Cutter? I was not aware that I needed anything but Houdini in order to get around RMan.

I feel like I am going in circles with RenderMan whether from a Maya or Houdini context and am trying to break out of that loop. I have always been able to figure out things and this one is testing me because I can't seem to settle on a good, simple and explanatory place to begin. Sort of like a super saturated liquid that needs a "seed" crystal to start the chain reaction of making sugar candy. I am looking for that seed crystal and for the first time I have spent longer than a week trying to find it.

This type of thing never happened with Mental Ray, VRay or Mantra: I was always able to find that "first contact" that set up the begining of the path that would lead me to being comfortable with those renderers. This is not the case with RMan and for the life of me I can't figure out why. Is it because I am not a coder/programmer/scripter? Is it because I am laboring under the false assumption that something in RMan (in the Houdini context) is similar enough to any other rendering engine and thereby act as the doorway through which I might travel?

I figured that one of the pre-made RMan nodes in Houdini 10 would at least allow me to lay down an AO pass on a sphere and plane. Is this not the case? In any event I just feel stuck and for some reason am convinced that If I could just do a simple AO pass on a spere and plane using the "ator_Environment" node gotten from TAB (in the SHOP context Network Pane)--> RenderMan Light --> RMan/Ator Environment and use that to shade the "Light Shader" of a Light Template node at the object level that that would be my solid entry point to RMan. It just doesn't ever seem to work and I get frustrated.

Sorry for the length but I am hoping someone reads it and goes, "Oh yeah! I felt just like that and I started with . . ."

Thank you again for the refs.

David