May 14, 20072:20 pm
Mental Ray Nightmare - Need Work Flow?!?!?
I am about to lose my mind.
I am using Maya 8.5 and the native mantal ray 3.5.
I am trying to do a render using an polysphere with an HDRI image on it providing the lighting.
The problem I am having is I cannot find any document that describes the Mental Ray workflow!
I want to use the finetrace preset and final gather.
In the final gather section I see the following properties:
- accuracy: 100
- interpolation: 1.0
- scale: 1.0
There is an options section as well, but I want to learn to set the main options first.
There is nothing, not a damn thing that I have been able to find to give me any workflow to determine the proper way to set any of these values! It is impossible to get a decent render without some idea of how to calibrate these numbers!!!
With fractional values lets say you have 1000 different values you could choose for each one that is 1000^3 possible combinations! At 10 minutes a render, lets see thats only 16 million hours or 19013 years. Sorry to say but that is a bit beyond my deadline!!!
There has to be a workflow to systematically determine the best values for these numbers. Considering even with the base settings a single render takes 5 minutes on my 2.8Ghz 1.5GB Athalon based system, I need to converge on the optimum settings in a minum number of test renders! I have spent days (far in excess of the time I spent building the model) and I have yet to get one single decent render!!!!
Can anyone point me to a document or video that describes a sane systematic workflow to determin these optimum values?
I tried buying the Digital Tutors crap but it is all but worthless. The guy uses his own scene then arbitrarily sets values that give great looking results without explaining a lick of WHY or HOW he determined those settings!!!! Also, the tutorial does not cover MR 3.5 and uses the old min /max radius stuff. At least with those old min/max radius values I had a method where I could measure the size of the scene in world units and set min and max to 1/100 and 1/10 of the measured scene size. With this new system of acccuracy. interpolation, and scale I have no clue where to begin setting values for each!
May 14, 20075:31 pm
First of all, using maya 8, maya 6 or maya 8.5 won't make any difference (well, except for the final gather speed).
Instead of using a sphere with an image on it to light, I'd suggest using a diffuse lighting approach... most of the shading relies on other parts (like specular, reflection, occlusion effects, etc). Now with diffuse lighting I mean placing lights (spot, point) around your objects.. taking care of the amount of light so you don't get overbright areas. This is of course based on the project you're working on.. if it's a dark scene, sunny midday, etc... the rest of the shading is basically shadows, reflections, specular and occlusion (try to give it some color so you don't have pure black).
If you still want light from a HDR image, try using fastest alterntives like lighGen by Jeremy Pronk (http://www.thereisnoluck.com) and lightDome by BinaryAlchemy (http://www.binaryalchemy.de/develop/lightdome/index.htm).
Using final gather may kill your deadlines.. just consider a flickering sequence!.. if you need an indirect pass, try using misss_lambert_gamma, so you can isolate the final gather contribution from the diffuse lighting, which leads to: use render passes.
Instead of losing your mind with final gather (I'm still using maya 8.0), try losing it in the post part.. you have more to tweak without eating all yout time.