help with mental ray

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Old 07 July 2012   #1
help with mental ray

from some reason i can not get true, realistic feeling to this render.. the screen does not have that back-lit
and i need it as realistic as possible? can anyone help me..
i enabled final gather settings for it are
initial FG .5
rays per FG 50
Interpolate 50
samples min 16 max 64 type i mitchell
i turned on mr photographic exposure control
shutter speed 1.433
aperture 1.403
and film speed 100
lights are 5 mr area spots, and 3 omni lights with one casting shadows
 
Old 07 July 2012   #2
If you're using linear workflow you can't use the MR Area Spots/Omni, you need to use Photometric lighting.

Your Final Gather settings are probably low, and you don't need your sampling that high, I usually use 1/16 for most things maybe 4/16 but you wouldn't want to go higher than that.

It's hard though to tell what is going on though without a picture to look at.
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Old 07 July 2012   #3
There are little problems in the model (and/or materials) and some in lighting, too. More than settings, this image requires a little more photographic approach.

- Amount of lights is more than necessary I believe.
- Front side is different from the product, it has a more glass like look. May be a beveled glass object may put it in shape.
- Consider putting some reflectors (White self illuminated planes) to get some beautiful reflections. Puk just an area light above and let there be some smooth shadows in stead of FG.
- Effect of FG is barely visible so I didn't even look at FG settings, but there are problems there, too. (Eventually there is no effect at all, but also there's not much things to have effect)
- Also apply some self illumination to the screen, this is SIII, not an HTC.
- Don't keep the sampling value that high (It makes addiction and ruins your life :P)

best regards
 
Old 07 July 2012   #4
thank you for all your replies, i thought i posted a picture, i am not sure why is not showing up
i am just trying to create a realistic studio for mental ray, that way i can just import and render my models...
 
Old 07 July 2012   #5
also if i use lower sampling settings it comes up choppy, like in the image above
 
Old 07 July 2012   #6
I think for some reason my browser is blocking photobucket pictures.

But from that image, I think the things I think that can improve it is to have some stuff for it to reflect, like an HDR map or like they were saying before adding some planes to reflect. Plus the screen doesn't look like you're using a self illuminating material

If that's lower sampling then it doesn't look choppy to me.
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Old 07 July 2012   #7
well to the people i work for, looks choppy so i have to improve the quality of the picture..
so i need to make an object with the self illumination in order to create believable reflections..
 
Old 07 July 2012   #8
Originally Posted by gumenimedo: i am just trying to create a realistic studio for mental ray, that way i can just import and render my models...
For that type of scene and with that goal in mind, I would highly recommend looking into using iray instead. You can still use things like the A&D material & mrPhotographic Exposure Control that you're familiar with but with far fewer settings to fiddle with to get great results. Even a modest GPU would be able to render that type of scene rather quickly even with options like DOF enabled.

FWIW provided you have somewhat of a modern GPU and are using a newer version of 3ds Max and want to explore iray I have several demo scenes on my website you can try. Including some studio configurations: http://jeffpatton.net/2012/07/iray-studio-scene-2/
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Old 07 July 2012   #9
Thank you Jeff, i actually came across your website before and your renders look amazing
i actually never tried iRay
 
Old 12 December 2012   #10
Sorry if this post is old but I was intrigued by this sentence:
"If you're using linear workflow you can't use the MR Area Spots/Omni, you need to use Photometric lighting."

Can you tell me a little more about it because I didn't know that.

Thank you!
 
Old 12 December 2012   #11
The MR Are lights are not physically accurate, they don't use real-world lighting values. To be able to use proper gamma and exposure and get things realistic then the lights need to be using realistic values as well.
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Old 12 December 2012   #12
Thank you.
You confirm what I was thinking, but as I'm not making a photo realistic short movie it should be ok if I use MR area spots and omnis ?
 
Old 12 December 2012   #13
It would be, you just need to make sure that your gamma correction is turned off and you aren't using any exposure control.

A reason also why you would want to use the physically accurate settings is because once you start doing it for everything then it saves time messing with values, if everything is the same scale and physically accurate then you'll know stuff that already works, whereas without it you'll have to mess with the rendering and do lots of tests until it looks right.
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Old 12 December 2012   #14
Thank you for your help!
I recently activated the exposure control because Mr zap wrote it can work with oldschool lights:

http://mentalraytips.blogspot.com/2...own-issues.html
(see "3: Use the exposure control with an EV=0.0")

My render is nicer since I followed his advice.
My gamma correction is always activated because I want a liner workflow.

Do you think I shouldn't do that?
I prefer not to change my lighting as it's already done... but I could

Last edited by welou : 12 December 2012 at 06:17 AM.
 
Old 12 December 2012   #15
If it's looking like you want it to then it's OK, the linear workflow and photometric lights are supposed to make it easier in general without having to do a bunch of render tests, if it's already looking good then you don't have to worry about it. It might be good to do everything physically accurate in the future though since it'll make things much easier the more you do them.
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