View Full Version : WIP - Help with Mental Ray setting's

02 February 2006, 12:21 PM

I recently started modeling an interior lounge to kick start my 3d portfolio,
I have always dabbled in and out of max over the years since 2.5 and now I would like to solidify all I know and just get down to creating some nice portfolio piece's.

My goal is to create a photo realistic or thereabouts image using Mental Ray I began modelling the room and objects in it, As I wanted to concentrate on the Lighting and rendering I dropped the modelling and began tinkering with MR refering to various tutorials to bring me to this point.

I now have a reasonable lighting setup, but still have some artifacts, I don't want to increase the photons or the sampling rate as the render time is quite high 10 - 20 mins on P4 3.06, 1.5G Ram. This is leading to frustration as I try and tweak the setting's to get it right.

MR Settings Used:

Max No. Photons : 24000

Light Properties: Avg GI Pho. 20000
Multiplier: 1.5
Decay: 2.0

Final Gather

samples: 1200
Radi in pixels checked

Sampler : mitchell
min: 1 Max: 16

To make a short story long, I would like to get some suggestions on possible setting's I could change. Just need to know what information people would need to help me.

Have a look at the image's and let me know what you think

02 February 2006, 09:21 AM
Its starting to look quite nice!! Good job...One thing that i can see from your image there is that your photon size may be a little large and thats whats causing the splotchyness your seeing in your renders try maybe increasing it one unit or increasing your GI accuracy settting...Also its hard to see from these low res pics but the geometry on your sofa looks a little odd it seems to be creating some weird shading effects but maybe thats just the lowres image...

02 February 2006, 05:37 PM
kevinmack, I am kinda in the same position like you. although I am workin maya for quite some time now, Iīve almost no experience with mray-GI+FG. (but I really need to figure that out cause it will be crucial for my graduation project)

I spent the last 2 days on cgtalk reading a lot about that stuff but still donīt feel a lot better about what I am doing to the values. I am fiddling around with a simple presentation of my room and when I was reading your values, I thought you could try the following:

increase the number of photons quite a bit! + reduce photn size like sully said
lower the FG samples / I feel 1200 are more than double the amount of whats necessary.

this is what I would try, but as I said I am nowhere near an expert on this subject :)
keep us updated!

02 February 2006, 11:56 AM
The image above is quiet nice but the drawbacks that im observing is that its a bit patchy and also the final gather rays are insufficient and also the image doesnt look realistic...

I recommend the following...

better go with the following settings...

Mental ray settings...

min sample level 1
max sample level 3

filter type box

since there are few reflections and refractions in the scene put just 4 rays for ref and refraction settings...

for Final gather settings...

just change the amount of final gather settings and dont change the min and max radius since it will automatically calculate by default...

Now turn on the GI with min settings...

if you find the above render is taking more time then just reduce the final gather rays to some small value...

render with the above settings and reply....with the image...


03 March 2006, 11:51 AM
Thanks all, for the replies, I will be implementing all your suggestions today, to see what results I get.

I'll keep you posted, with hopefully some improved renders.

03 March 2006, 04:05 PM
After spending some time trying recommended settings, I was unable to improve the render, apologies for not getting back sooner.

But I have stumbled a tutorial that throw's some light on what way the setting's in mental ray affect your render :bounce: , hope this helps those in need.

Go here :

Then into Free Stuff -> Tutorials -> Lighting and Rendering -> "Simulating GI in Mental Ray"

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03 March 2006, 04:05 PM
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