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Author Topic: very random render times  (Read 4860 times)

F10Nick

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very random render times
« on: October 26, 2009, 12:04:32 AM »
Hi,

We have a project which we are just trying to render now, and frame time are being very random.

a few different machines will be rendering at about 7 or 8 mins a frame, and then suddenly a machine will take 15 mins on the next frame, or even sometimes 30 or 40 mins. And its not consistent which machines do it, and happening a lot.

This is a big problem as we have 4000 frames to render, and this is massively affecting the average frame time, so I cant even accurately predict how long its going to take.

Scene is a large landscape, so there are huge amounts of trees consisting of many vray proxies being scattered with Forest pro.

Does anyone have any suggestions on this one please?

cheers
Nick

iToo

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Re: very random render times
« Reply #1 on: October 26, 2009, 04:44:20 PM »

We have not reported problems of random render times using VRay, but there are some factors that can affect:

- What is the value of Render Setup->VRay System->Memory Limit ? 

If you are using the default value (400 Mb.), increase it to 2000 Mb.

- Where are the proxy files stored: locally or in a network path ?

If possible, try using meshes instead proxies. This can reduce the render time and solve some issues.

Carlos Quintero
iToo Software

F10Nick

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Re: very random render times
« Reply #2 on: October 26, 2009, 08:50:37 PM »
Many thanks for reply, Carlos.

memory limit is set to 4000mb at mo.

interesting that meshes can reduce render time, I shall test that. We have always used proxies since another big landscaping project that simply would not render with meshes, but would as soon as we proxied everything. Maybe I dont fully understand their use.

Cheers
Nick

iToo

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Re: very random render times
« Reply #3 on: October 27, 2009, 04:48:21 PM »

The benefit of using proxies is that the geometry is stored in an external file, saving space from the main scene. But really, you can render thousands of instanced meshes (instances... not copies) getting similar render times. Futhermore, the proxies add a small penalty to the render time, i don't know sure why... probably because the geometry must be loaded from disk.

As instance, here are the results of a render time test, using 1500 trees (200k faces each one):

Forest with meshes:   1:06
Forest with proxies:   1:15
Instanced meshes:    1:27
Instanced proxies:    1:37

The difference is not spectacular, but as you can see, the times using meshes are slighty better. I have used Forest Tools (Utility panel), to convert the trees from Forest to instanced objects.

Carlos Quintero
iToo Software