Huge difference in render view to batch render times

[Steve Davy]

Here's this old hoary chestnut again.

I have a scene that renders at full rez and quality into render view in around 2 minutes.

When the same scene is launched as a batch, I'm looking at xx minutes per frame. This is nuts, and unfeasible in terms of render time. There is no obvious reason for this at all.

The scene does contain displacement, particles, expressions, raytracing with reflections and refractions, transparency, and deformers, and a lot of history. But, obviously none of this should matter (and the extended render time is nothing to do with runups or caching as I'm launching the render with the scene open in Maya and watching the render progress. It's the render that's taking a long time).

What on earth can the problem be?

[matt estela]

is scene load/scene translation slow? I've never looked into it closely, but i assume batch starts its own non-gui maya session, loads the scene, translates into your native render format, THEN renders; if there's a noticeable delay befor the render hits 1%, that could well be why.

if its slow after hitting 1%, maybe multithreading? is it turned off by default?

is this maya software render or mentalray?

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[rotte...@gmail.com]

I would check if the render machine is using all or just a single proc per render. My old farm was set up that way, where an 8 proc machine would render 8 frames at once only 8 times slower than my local renderview. 
It may also be pulling major files across the network, or the maya scene takes so damn long to load. Use binary scene rather than an acsii if this is the case.

Jim

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[Steve Davy]

Mental Ray....

This was not a scene/asset load time or network speed issue either -- the scene was already loaded into Maya and I was launching a batch render straight from the GUI. It was not just that the render was slow to start (though it was), but that it crawled even once it got started.

In the end I had to run geo caches on everything possible and strip out absolutely all the rigging (which I guess is a good best practice for rendering anyway) and that seems to have cleared it. But it's kind of aggravating to not know why Maya does this sometimes.

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From: ma...@tokeru.com
Date: Thu, 24 Jan 2013 11:42:09 +1100
Subject: Re: [maya_he3d] Huge difference in render view to batch render times
To: maya...@googlegroups.com

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[ryan harrington]

Hi Steve,

Seems you found a solution, this is a bit late but might help in the future....

I had a few weird scenes a while ago where cached dynamics still did a run up through the entire frame range, for every frame, even though it was reading a cache and the 'is dynamic' attrs were flagged off. Tell tale, at a glance symptom is increasing render time through a frame range. 

There are a few batch render via the renderview scripts about. Some are better than others.

I would recommend one, but I can't remember which one worked best for me. have a poke around Creative Crash. This worked round the problem described above.

It's a drag because doing a distributed render means kicking off small batches manually on multiple boxes.

best,

Ryan