View Full Version : Mental ray and Combustion!!

02 February 2005, 02:50 PM

I'm having an issue with using mental ray with combustion, does anyone know how compatible mental ray is with combstion? i've tried rendering rpf's with shaders such as sss fast skin in my scene but these shaders turn out being black when the rpf is imported into combustion:shrug:. My main reason for using it is to use DOF and motion blur for an animation so if anyone has any ideas how i can achieve this any other way would be cool.

thanks in advance!

02 February 2005, 10:15 AM
You didnt mention what program you're using.
If you're rendering from Maya, use .iff Maya native file format. Combustion will be able to exctrat the z-depth .
But as a generla solution. Render your color pass, then render again your scene using any zdepth shader to any file format such as tiff or tga.

02 February 2005, 12:54 PM
3Ds max 7, rpf's are native to discreet programs as far as i know, sorry totally forgot to mention the program.

02 February 2005, 06:13 AM
actually this just came up the other night at the Chicago Combustion User group. RPFs are not the end all be all thing to do. a couple of the post people there never use them because they can be a bit limiting

I know that in Combustion 4 it will allow you to BUILD a RPF file from individual files inside without having a RPF file.

I personally would do the Motion Blur in Mental Ray. it's by far a much cleaner and easier to setup blur than that of Combustion. Also the Depth of Field may also be easier to do in Mental Ray. Especially considering you have to already properly setup the camera to out put the Z-depth channel.

you may also be able to render out the z-depth channel seperately and use that to control the blur, but I do'nt think this woudl be the same as a true DOF and C4 may be a nessecary upgrade to do that.

02 February 2005, 06:43 AM

For the motion blur you could try to render a motion vector pass and use ReelSmart Motion Blur from Re:vision Effects to do a 2D motion blur. The results are pretty impressive.

As for the DOF you can try the Compound Blur workaround using a depth pass.

In C4 you'll have full access to all the 3D Post operators from C* using the G-Buffer Builder to assemble a 'RPF' file/sequence from individual passes.

Personally I try to avoid using or developing pipelines involvind RPF since not all the 3D applications have a good rich pixel format implementation and neither all the compositing packages read them. So I still rather have several passes to play with since I find it more flexible and easier to deal with case you need to re-render something.

What I'm really looking foward is the OpenEXR file format.

Hope this helps,

CGTalk Moderation
02 February 2006, 07:00 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.