Rendering aur cache files with the volume grid in houdini how to use smoke rgb ?

[Ghost3d]

Hello I have a cache I created in maya. I am using RGB for smoke color. trying to render in houdini with the volume grid . in the volume shader I do not see an option to use RGB for color . just has constant color. how would I acces the RGB attr from the volume grid?

[david.anastacio]

Hi,

I'm not familiar with .aur caches inside Houdini, but do you see your RGB attribute in the geometry spreadsheet?
If yes, have you tried using it in the color parameter of the Fields tab?

Best,
David.

[Gosho.Genchev]

Hey Ghost3d ,

The name of the RGB channel should be specified under Fields -> Smoke -> Color. I believe the default name exported by Phoenix FD is "ColorR_phx", "ColorG_phx" and "ColorB_phx". You should specify "Color*" under Fields -> Smoke -> Color.
You could check the names on the "Channel Mapping" tab of the Volume Grid Cache SOP.

// once you do that, the "Color Gradient" button on the Smoke tab will no longer have any effect. It is only used when the specified channel for smoke color mapping is of type float. We're working on supporting the Volume Grid texture for more complex workflows, e.g. loading a color channel, remapping it and plugging it in the "dtex" input socket of the shader. This should come to the V-Ray 5 builds in a month or so.

Best regards!

[Ghost3d]

ohh ok color with the "*" was trying to figure out how to merge it into a single vector .

thanks !

[Ghost3d]

just FYI Color* did not work but color* did .

[Ghost3d]

actually when I put Color* the color gradient is disabled but then nothing renders at all. if I put color* it renders again but not picking up the rgb attribute . not sure how this works sorry.

[Ghost3d]

figured it out needs to me in a vray material builder and not the shader that gets created when you use the import aur menu feature .