Normal Pass output for volume cloud

[kensonuken]

Is there any possibility to renderout worldspace normal pass to balance things in post...?

I mean what could be the shader connections... any sample file for this?

[Jason]

Is there any possibility to renderout worldspace normal pass to balance things in post...?

I mean what could be the shader connections... any sample file for this?

You can simply export N in the "Extra Image Planes" section in the ROP. How you want to deal with opacity is up to you. (See attached hipfile)

This will be the gradient of the Volume in camera space. If you want it in Object Space or World Space, you'll have to, in your shader, take N and wire it into a Transform VOP (direction, current->world) and wire that into a Parameter VOP (export toggled) and then use this variable in your VEX Variable field in your "Extra Image Planes".

Does that make sense?

Jason

volumenormaloutput.hipnc

[kensonuken]

thanks jason. what if I want bent normal? then do i need to write a shader for it? do u have any shader which can output bentnormal...coz i saw some video stuff from Digital Domain where for the Day After tomorrow They seem using that but I believe it was just worldspace Normal rather than Bentnormal... what do u say.. which one would work best?

[symek]

thanks jason. what if I want bent normal? then do i need to write a shader for it? do u have any shader which can output bentnormal...coz i saw some video stuff from Digital Domain where for the Day After tomorrow They seem using that but I believe it was just worldspace Normal rather than Bentnormal... what do u say.. which one would work best?

Ready to use bend normal tool in Houdini is a second version of occlusion() call in VEX. This is a ray tracing call, so you most probably wouldn't like to use it with a volumes. I'm curious about point cloud/normals method as a replacement for ray tracing but as far as I know there isn't such shader around (for filtering point cloud normals) and hard to say how it would work in pair with volumes.

Besides that I've never heard about applying some GI on volumes. Most often people try to stick with local illumination and classic three light setup tough this is definitely interesting topic

cheers,

sy.

Edited August 24, 2008 by SYmek

[kensonuken]

well symek the point is that i dont want to go with gi solution for volumes since i would like to control everything on post its better to get N out of it. But since we need to render out occlusion as well i think it will give much realism.. wat do u say?

[symek]

well symek the point is that i dont want to go with gi solution for volumes since i would like to control everything on post its better to get N out of it. But since we need to render out occlusion as well i think it will give much realism.. wat do u say?

I say people usually try to avoid computing anything but opacity on volumes because it takes ages, and most often soft shadows (depth map based) give much of that self occlusion look people need.

Edited August 24, 2008 by SYmek

[kensonuken]

how do i get bent normal?

[Jason]

how do i get bent normal?

The occlusion() VEX call can return a bent normal. However, calling occlusion on volumes is gonna be a killer:)

void occlusion(float coverage&, vector missed_direction&, vector P, vector N)

[kensonuken]

yeah then I think using just N and comp it would be a better option since there wouldnt be any steep intersections in the volz..