[Bf-committers] Re: render passes & workflow

[Roland Hess]

Almost any article I've read on using pass rendering seems to focus  
on doing your final renders in passes for greater flexibility down  
the pipeline. Now, if the rest of your pipeline is Blender's  
compositor, then it's not an issue. However, if you're using  
something else as your target -- putting this in with a bunch of  
other apps, or handing the files off to another "department" for  
compositing/sweetening -- you would want to be able to have all  
passes saved into a file format straight out of the renderer in which  
each pass is a layer (per the image editor of your choice) set with  
the appropriate blend mode flags so that rendered files can be opened  
in either a still editor or compositing app with layers (passes)  
intact, blended properly and ready to be tweaked.

Unfortunately, OpenEXR isn't up to this sort of challenge right now  
-- the file format may be able to handle the channels, but there  
doesn't seem to be support for having those appear in image editors  
in a useful way. Of course, it wouldn't hurt if Blender could read  
such files right back in at a later date, allowing you access in the  
compositor to each channel set appropriately.

On Dec 6, 2006, at 4:33 PM, bf-committers- 
request at projects.blender.org wrote:

> Now that the basic code work was done, it's time to check on usablity
> of pass rendering.
> (No Trip, not usuability of compositor, that's another project!).
>
> Two ideas I got in mind now:
>
> 1 Make the "Combined" pass (optional) exclusive passes.
>
> My assumption is that you only use passes for specific cases, like  
> only
> the shadow pass or only the reflection pass. In that case, a composite
> now is difficult to use when "Combined" has this pass info added (for
> example blurring shadow).
>
> 2 Give RenderLayers two new options:
>    - Light (Group) override
>    - Material (incl Node tree) override
>
> This option will render everything in the RenderLayer with a specific
> group of Lamps, and/or with a specific Material. That's a much more
> powerful way than define a "custom pass", since then you have the the
> RenderLayer result again with all existing passes available.
> It also gives a nice use for the to-be-added Python Node shaders. :)

Roland Hess
IT Manager/Digital Prepress
Reed & Witting Company
Pittsburgh, PA
412-682-1000
rolandh at reed-witting.com



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