Render time exploded

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  09 September 2012
Render time exploded

Hello guys,

I have made a fairly basic scene, only 10k poly and everything was nice and fast. I was rendering in 720p with textures and light in about 15 seconds per frame. Then i don't know what happened and my render time jumped to 2-3 minutes without adding anything new. I went and checked to see if i duplicated a light or something(i am using physical sun and sky) but that was not the case.

Is there any method to find out what is taking up my render time?

Other details:
-using mental ray
-i7 quad core 3.4ghz with hyper-threading
-max sample level is on 0

The scene
  09 September 2012
It's pretty much impossible to just guess, but...

Things that generally increase render time drastically:

Soft shadows - (raytracing more samples = nicer look = longer render)
Blurry reflections - ^
Blurry refractions - ^
SSS (depending on settings)
Final Gather/Caustics/GI
Anti Aliasing settings (you said your max samples were at 0 so this shouldn't be the case but double check)
  09 September 2012
Also, was that a difference between rendering in the render view and a batch render?? Sometimes a batch render doesn't use all cores unless specified and render time jumps.
  10 October 2012
I cannot troubleshoot your scene right now, but when I have this problem I sometimes

select the objects I want to render (including lights/cameras),
export them as a .mb,
create a new scene
import the .mb

You'll have to remove the namespaces but it can really help when a scene gets bugs


That being said, a + 2 min in a scene is not uncommon... But you're right that it's a good idea to know why.

Last edited by RickToxik : 10 October 2012 at 01:13 AM.
  10 October 2012
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