View Full Version : mental ray production shaders - whats wrong here?? HELP PLEASEE!!

06 June 2010, 01:31 AM
hi im having a very strange error with linearworkflow in mental ray for maya... or maybe not...??

the thing is, that i was rendering an helicopter at work with production shaders and linear workflow in maya, and other person that works here was telling me that the process is just wrong, and the rendered image was wrong at all... so... then he showsme in photoshop how he thinks that the image should be... and for some reason i think that his version is somehow better, and more realistic than what i get rendering in maya with the production shaders

i could get the same result increasing the gama in the mia exposure simple like to 3.1.. but obviously that could be wrong, because i should get the correct result with gama at 2.2... so everything else is fine in my linear workflow, i think... my setup is exactly like master zap explains...

so what could be wrong?

this is my version:

this is the version of the other person:

06 June 2010, 02:31 AM
If your co worker is rendering in 3.1 gamma then hes doing it wrong. The second render looks washed out. What is your set up?

06 June 2010, 03:31 AM
my set up is exactly like master zap's production shader examples, but the mirrorball... is not exactly the spherical image of the place... is just the same image as the background with the color multiply to 1.5 as well... could be that the reason????? i dont think that, because, most of the scene is gray-bluish...

that second image is just an aproach of what he did, he basically tweaked the curves in photoshop based on hotspots/coldspots in the background image, but his result was a very pretty well integration...

so now im confused, because i dont get that kind of result, but im using the apropiate settings, and when i see this first image i feel like is not really well integrated in the background, but i have the correct setup in the production shaders! then why is that??

06 June 2010, 09:16 AM
You must be kidding,

the second image looks totally wrong - washed out - terrible..
Your image looks far more realistic....
Just look at your helicopter and compare it to the other.


06 June 2010, 06:30 PM
Your image in my opinion its correct.

I think that your co-worker is trying to achieve some sort of atmospheric effect.
you can try with visibility distance in the mia_Physicalsky and also pati_volume or fluids can achieve that kind of effects.


06 June 2010, 04:37 PM
I think they're both off to be honest. Yours is a better start point I think, but it needs heavy color correcting. you can see that the white and black points dont match between the plate and the helicopter.

As to the other guys work, well I see what he might have been trying to do, but it didnt execute properly. way too much gamma, its all washed out.

06 June 2010, 05:43 PM
thanks for the responses...

at this point that work, had some improvement... but i would like to hear your opinions too in this...

06 June 2010, 07:33 AM
Looks very good. Some small adjastments (like grain, correct motion blur on propeller ) and would be perfect :)
May be it worth to make more powerwul elow highlight on right side of helicopter.

06 June 2010, 06:41 PM
yeah, thats heaps better. The second heli in the background looks a bit wierd but the hero one matches the plate alot better now

06 June 2010, 09:11 PM
So what did you do? :)

06 June 2010, 09:33 PM
linear workflow is a "correct" method of working, like sharpening your pencil often when sketching and drying your paint brushed between different paints. It has nothing to do with getting a render that looks good. Its gots nothing to do with your images being good or not ( which by the way your original did look better)

06 June 2010, 04:22 AM
Also the background haze looks very hazy. Your helicopter being closer to the camera should naturally have more contrast.

06 June 2010, 02:55 AM
So what did you do? :)

well this is the almost final version:

what i did, was... added some volumetric effect with the physical sky envirioment shader atributes mixed with production shaders... then... added some extra fg contribution of shader, and more blue tints with casters of blue incandecent tones... then blurred with the traditional blur system... with many motion steps for radial blur... so yes... it was very long render with the blur.

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06 June 2010, 02:55 AM
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