Can anyone tell the best way to set up multiple render passes (zdepth,shadow pass, occluision, etc.). Never tried it in houdini.
thanks
—jfugh

I'm a big fan of Takes and then you can just have several mantras set up for each take (A beauty mantra, a spec mantra, etc). Merge the mantra nodes and then render them all at once.

This is a bit old but very useful. This is how I learned Takes. Not sure anyone teaches it. http://www.sidefx.com/index.php?option=com_content&task=view&id=451&Itemid=132 [sidefx.com]

It's a bit clunky, but sometimes I use object merge and a new material and a new object for each pass, in mantra/objects you can tell mantra which objects in a scene you wish to render, you can then wire the mantras together and ‘render control’ on last mantra, and use the settings provided. It's not quite that simple, but with a little practice it works fine, being ‘mechanical’ there's little room for error.

Takes is probably ideal, but I don't use it often.

There is no ‘best’ way, it's driven by need, environment and technical expertise with the package. We use scripts here, using group masks for matte, phantom, etc. Certainly some people are happy with the takes approach, you just need to be careful with takes…they are human-error prone. Mind you, if you're not comfortable with scripting, that's pretty error prone too.

Cheers,

J.C.

On a current job I set up my renders using a combination of export parameters from shaders , pre and post render scripts and bundles ,with all the geometry using delayed load. I also made sure I had a selection of presets so I could drop a Mantra Rop then from a menu select a set of parameters to have a Production render / Low res render plus list of standard exports .Very easy to manage , no need for takes or custom scripts.

I'm playing around with multipass rendering too, thanks for your very insightful posts and examples.

Regarding circusmonkey's approach of exporting out parameters from the shaders: how do you handle scenes with many shaders? For example, if you want occlusion,id,shadow passes, than all the shaders need to have those exports in them, if I understand the method correctly.

Is there a way to generate/edit these exports from a single place, rather than having them in all shaders? Would that be something that you could do with a pre-render script?

Thanks!

Regarding circusmonkey's approach of exporting out parameters from the shaders: how do you handle scenes with many shaders? For example, if you want occlusion,id,shadow passes, than all the shaders need to have those exports in them, if I understand the method correctly.

All my shaders have exports in , just like you would with Prman.

Is there a way to generate/edit these exports from a single place, rather than having them in all shaders? Would that be something that you could do with a pre-render script?

The single place they get edited from is the Mantra ROP . Thats where I decide if I want to use my exports or not. You also need to look at “ Bundles ” I use them heavily.

I'll look into it, thanks for the hint.