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JohnBellas
12-02-2006, 01:29 AM
This is a blatantly noob post, but it needs to be answered regardless, and may clear things up for mental ray newcomers.

My company is delving into mental ray for the first time, and I have found that it can kick out beautiful frames at a semi-reasonable speed with a low-detail scene. However, when we attempt to render a higher res model (about 40,000 faces) with global illumination, caustics, ray-tracing, final gather, and photon-emitting lights, it takes up to an hour to kick out a single frame at 960x540, even with all textures stripped away.

We are considering getting a new machine more catered to rendering high-end mental ray scenes, but for something like i mentioned above, can a $5,000 pro-sumer grade PC even handle it, or do we need to get something like an SGI?

Any insight would be greatly appreciated.

maxwater
12-02-2006, 02:47 AM
basically 40.000 faces is not too much...
many in here are handling models with 3.000.000+ faces

Myliobatidae
12-02-2006, 02:54 AM
Forget about SGI, buy a dual-quad workstation (8 cores)...
hmmm...but do you need extra licenses with MR and Maya, I think with Max, it comes with unlimited network rendering, so the number of CPU's dosen't matter with Max...

fabergambis
12-02-2006, 10:56 AM
The most important thing with Mental Ray, is learning to optimize scenes with right render settings (various FG and GI Radii, BSP settings...) and right materials (MR Custom Shaders as ctrl_shaders or new Arch&Des shaders) instead of buying a new powerful workstation or SGI...

Exo7
12-02-2006, 03:12 PM
I second what fabergambis said: at a certain point (when u activate GI+FG+...+...) you can lower some specific settings without quality loss, so to speech. Especially when using GI, fg multibounces is desactivated automagically. Area lights are real exponential killers if not optimized, I almost prefer using brute Monte-Carlo path tracing :D

Learning to optimize is our graal here !

CiaranM
12-02-2006, 04:00 PM
That sounds like a scene that should render in a couple of minutes on a modern machine if properly rendering is set up well. Perhaps you could share a scene so we could help you optimise your rendering?

dagon1978
12-02-2006, 04:06 PM
Forget about SGI, buy a dual-quad workstation (8 cores)...
hmmm...but do you need extra licenses with MR and Maya, I think with Max, it comes with unlimited network rendering, so the number of CPU's dosen't matter with Max...

nope!
the mental ray licenses are per cpu not per core!
so:
1 dual-quad core = 2 license (for satellite)
4 dual-quad = 8 license (for satellite)

maya complete come with 2 additional satellite licenses (mean 1 server = your dual-quad + 2cpu x n_cores)

maya unlimited come with 8 additional satellite licenses (mean 1 server = your dual-quad + 8cpu x n_cores)

fabergambis
12-03-2006, 11:30 PM
:rolleyes: ...dagon, I was waiting for it: you know what I mean?:)

dagon1978
12-04-2006, 08:59 AM
:rolleyes: ...dagon, I was waiting for it: you know what I mean?:)

eheh ;) i know

JohnBellas
12-04-2006, 11:51 PM
well, that certainly clears some things up for me. i tried some optimizing here and there, and got much faster results. i think my problem was that i was basically turning on mental ray and hitting render, in a scene that was lit for maya software. seeing as how i'm new to MR, i'm not quite sure if the numbers i tweaked were the most efficient ones to lessen, but i did get some results nonetheless.

i'm not quite out of the thick just yet, though. part of my "optimizing" was that i had to strip my scene down to a single white lambert and a single light just to get it to render anything. if i use a few lights, or if i render with textures applied, it just processes and processes until it runs out of memory and errors. the machine has two gigs equipped. when i get an "error: out of memory" or "free memory is low" error, is the machine's RAM really filled up, or is it just trying to say the machine generally isn't up to spec? i wish i could share the scene file, but unfortunately the job is confidential.

fabergambis
12-05-2006, 12:18 AM
How many faces has your scene? It's very strange that MR goes out of memory with only a few lights (maybe Area lights?), some textured Lambert shaders and 2GB of RAM! You should try to use Large BSP setting, or checking for Paolo Berto's Masterclasses with many useful informations about MR optimizations. It's called "Tricks4Kids vol.2" (http://www.jupiter-jazz.com/wordpress/wp-content/data/tr4kv2/html/index.html) and you MUST read it ;)

dagon1978
12-05-2006, 09:14 AM
another question, are you using raytracing in both mental ray and maya render?

JohnBellas
12-06-2006, 12:24 AM
the scene has around 40,000 faces, which i hear is not that much. i dont think i was raytracing in the software renders, but i definitely was with mental ray. if i recall, both the reflections and refractions were set to 3 in the render settings, although there were no reflective surfaces, so maybe that doesn't even matter. what exactly is BSP? do you mean binary space partition? i've seen it used in game engines, but i didn't know 3d apps used it. where can i find that setting?

chocot
12-06-2006, 10:25 AM
two step to try to solve this

-put to all objects the same materials grey/white, for draft construction ( best way to achieve quickly first lighting setup (delete windows glasses temporary)-if you have at least two important lights in your scene, render images with one turned on and the other off, to see if one is just..bugging..
-i always do test with empty room (or scene or...) no useless object during light set up. small res of course .
you can't have such times rendering, it's impossible..:twisted:
one other thing i advice for you ; buy a good machine ( dual x2 extreme ...new ones) with good cg if you can for a 3000 $ max , a flexible system is not usefull, just A goof One, quick ram, good HD, good MB. plus you can buy 2 low cost machines 2* 800 -1000 , no cg, jst gigabit network and a d950 as core or more, for the price i think you can even get a better processor.
Buy exactly all same client pc if you can//

In fact there's no need at all to get the BEST computer you can have at any time..very very very decent jobs have been done with olders computers, there are many years that i admire cg images and they nobody had access to nasa computers for rendering so , they're is always a way ti get what you want. but just to take an example, in about year 2002/3, machines could only get half of the compute power of nowadays new machines..an old 2 g is NOTTHING compared to nowadays everybody's computer..it was very expensive...

Maybe people can tell what they think of it, to me this is the best choice if you have a 5 000 $ dream to buy for your work. 3 machines will always work quicker than one, even if it cost 8 000$

i do have one for my network which is a bit older than the others ones , it slow down process, i prefer not to use it at all. it's just a P4 2.8 ...

fabergambis
12-06-2006, 03:01 PM
what exactly is BSP? do you mean binary space partition? i've seen it used in game engines, but i didn't know 3d apps used it. where can i find that setting?


Yes, Binary Space Partition, and you can find it in Renderglobals>Mantal Ray Tab>Memory and Performance where you can find Memory Limit parameter too: if you've got 2GB RAM you should set it to 1600 I guess...if default setting of 800 is set for 1GB Ram.

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