Is RPF the only format to use 3D post fx?

#1

Hi!
I use Maya and I found out that in combustion tutorials they always speak about rendering in RPF-format and then using Z-buffer builder etc. to create post fx like fog.
I can’t render in RPF in Maya. What should I do to make 3D post fx possible in Combustion 3?

#2

You can use RLA or other format that it stores the Z-depth. Or you can use the z-depth or other channel as map for effects (compound blur for DOF, alpha channel for fog). But other functionalities of Combustion like 3D Motion Blur, 3D glow many times could not be used

#3

Your best bet would be to upgrade to Combustion 4 and use the G-buffer builder. This allows you to combine seperate images or information from different images into one operator you can then do your 3D Post fx. One note on Maya: Maya, atleast in older versions, wrote the header info for RLA files differently from other packages so zdepth and other information may not load into Combustion. Search for Maya and Combustion in this and the Compositing Forum for more info.

-Eric

#4

A workaround I found when using Combustion 3, if you wanted to apply say 3d blur was to take a copy of the footage, matte it using a luma key based on the z-depth and then apply the blur to that. Despite all the hype I recommend against doing dof in post if at all possible. Because if you have say a green circle on a blue background. if you blur the background, the green circle will still “glow” outside of it’s sharp crisp outline. You’ll see this all the time in games and animations where they tried to do DOF in post.

But like I said, I don’t know if this is what you hope to do, but the same principle can be applied to just about anything. On a shot for spiderman, I used the Zdepth as a lighting pass, and simply overlayed as a multiply.

All in all, I’ve found, that while the G-buffer builder can be extremely helpful when it comes to say material channels, there is always a work around involving mattes or layer blend modes.

Another option: Use the OpenEXR format.

#5

OpenEXR is a option but many softwares don´t support this file completely ( for example only the 3ds MAX8 supports this format). You can use the Z-depth directly as alpha channel using the set matte and control the intensity the effects (DOF, fog) using a operator of brightness and contrast

#6

Only Max 8 supports it natively.

Maya and XSI both have plug-ins available. On my last project we used a Targa/OpenEXR work flow for all of our Maya Renders -> Combustion.

3D studio max 8 just makes everything friendly and happy.

#7

These plugins support options like object/material ID, velocity? If its support, as you use these informations in the Combustion, use like maps (keyers), plugins ?

#8

I can’t say for sure whether or not Maya 7 supports Zdata in the OpenEXR format. I don’t actually remember using Z-depth on that project specifically. I know OpenEXR supports an infinite numbers of layers, specifically including z-depth.

You would need to use Mental Ray as your renderer though as I don’t believe Maya Software supports OpenEXR.

OpenEXR.org, try downloading it and giving it a spin.

#9

I must not have been clearly, sorry. These plugins ( for XSI, MAYA) support (create this information) informations like object ID, velocity? The MAX8 support these options in OpenEXR format. In the case these channels, they are separate (many files) like you use in the Combustion 3 (without G-buffer Builder)

#10

Yeah theoretically, they would all be saved in the same file, much like RPF. This is only in theory though, I’m not sure if Mental Ray 3.3 and 3.4 have been written to do that though.

I wouldn’t expect Object ID to be saved however, since I believe that is unique to 3d studio max. Same with material ID.

#11

OpenExr might support an unlimited # of “layers” (channels, buffers), however depending on your compositing software you might not be able to read all of those layers/buffers/channels. Fusion5 only supports a maximum of 15. Mind you, you can always code your own “reader” for whatever software you’re using provided you have the sdk(usually free) and the source code for the file format so you know what you’re writing. It’s not trivial by any means but a good programmer could do it for you.

#12

Currently none of the Autodesk/Discreet compositing products support Extended Data Channels (G-buffer channels). Combustion only supports the RGBA channels in an EXR file. However, I have been told more than once that they are looking into how to handle this. Only time will tell if/when full, or atleast some, channel support is supported.

-Eric

#13

The other way around this however is to render the data that you need (normals, uv’s, diffuse, specular, ambient, depth, alpha etc. -anything you’d be putting into an opneExr buffer) as separate rgb images and then deal with them how you will.

In Fusion you can make a macro that uses rbg(a,z) images as inputs and the channel booleans tool to “build .rpf/.exr type images”.

In Shake there’s the layerX and colorX nodes.

And as someone mentioned previously apparantly combustion has a G-buffer builder. Pretty much any compositing software that can use expressions, will allow you to script something up pretty quick to perform operations based on these types of “layers/buffers”.

#14

Only the Combustion 4 have the G-Buffer Builder, but this not capable the use or extract the other channels presents in the OpenEXR (like PiXeL_MoNKeY spoke). For use the G-buffer builder you need use many files or one file in this format supported for Combustion to read these extra channels

#15

Simply by using OpenEXR as your file format will not automatically give you the different “channels” you require (normals, uv’s, color, diffuse, spec etc…). The OpenEXR format simply provides you with extra buffers/channels to put in whatever data you want to. You still need to generate these images regardless. You wouldn’t be using OpenEXR as your image format, that’s what my entire post was about…not using openEXR. Render your g buffer data as rgb data and there you go. problem solved.

QUOTE=Vympel]For use the G-buffer builder you need use many files or one file in this format supported for Combustion to read these extra channels[/QUOTE]

Isn’t this what I addressed in my earlier post? If you’re going to be generating this data anyways, render it out in an image format that you’re compositing application can actually read natively, then you can do whatever you want to with this data. Even with the G-buffer builder, because the G-buffer builder expects rgbaz data, you will render rgbaz data and then feed that into the G-buffer builder.

This will give you the same functionality that you’d have if you had rendered using rpf or OpenEXR.

#16

I understand your previous post , more the Combustion do not interpret all information (like z-depth, UV) contained in a OpenEXR file with this information, but only RGBA channels. For use these information you need many files (“normal” images) and G-buffer builder (like you spoke in a previous post using booleans in fusion)

#17

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