Mental Ray Max 9

[claytonjamesblack]

This is my first time using mental ray in Max 9 and have many problems and this is just 1 of them. How do I get rid of the dark grey circles found around most of the edges of the buildings. I'm using MR sun and MR sky, final gather, GI. Attached is the image and the Final gather and GI presets. But that might not be the problem?

[mbowers]

I don't know much about MR, but it seems like the number of photons is too low.

Try bumping it up (maybe 2000) and see what happens.

[louis.cho]

make some test without FG. Your photons are definitly too low. try to pop average nb of photon per light to 500000 and put 50 in both Nb of photon per sample.

 

If then It's look good, put FG on

 

I am not an expert but I think it's a start

[Quique]

Hi there,

 

My recommendation for this outdoor scene is to turn off Global Illumination completely and rely on Final Gathering.

 

In a scene I created recently, I used a mrSky (multiplier 1.0) and an IES Sun. Exposure Control was set to Logarithmic with Exterior daylight enabled. I'm attaching an image with these settings so that you can see the results. My FG settings were at the Medium preset with Diffuse Bounces set to 0, but since we're not using GI, it would be a good idea to set this to a positive number (of course renderings will take more time).

 

I hope this helps.

 

Quique

[Macer]

FG alone should work fine. However if you want to master GI switch fg off and try raising various settings and testing until you have good results. I found it the best way to get your head around what does what, even if it is time consuming. Its also worth playing around with the maximum radius too, I've found that this alone can solve some issues - not sure how it affects render time though.... ....still trying to figure loads of this stuff out myself!

[Justin Hunt]

Your settings are way off, seeing that you are interested in getting a decent GI render start with no FG

 

try these GI settings

Max no Samples 500 for testing 1000 for final

Max sampling radius = set it relevant to the size of the scene

Trace depth 10 (no less than the sum of Max reflection and max Refraction)

Max reflection 2 ( unless you have alot of transparent sufaces keep this low)

Max refraction 2 ( same as max reflection)

 

Average GI photons 10000 is fine for testing , 100000 and more for more detail

Decay 2 ( 2 is for inverse quare falloff, lower numbers = less fall off and brighter scene but dont go below 1.5)

 

All objects generate On

 

FG settings, what you have are crazy

 

Preset Low

 

FG density 0.4 for tests 1 for final

Rays per PF 100 for test 250 for final

Interpolate 30 for tests 80 for smoother

Diffuse bounces 1 for test , 3 for more effect

 

Max depth 10 ( for more contrast lower numbers)

Max Reflection 5

Max Refraction 5 Both of these increase with more reflective/ refractive surfaces.

 

I do sugest you read and do the tutorials that ship with max to get a better understanding of these settings. Also use exposure control.

 

JHV

[claytonjamesblack]

Cheers guys for your help. Justin I put in your imformation and that has come out alot better. A problem I also found, I was using a saved FG / GI setting. I fell like an idiot now - attached is a quick result. Alot more work is needed thats for sure, ie materials will be my next challenge!!

[nisus]

Hi,

 

FG alone would work, but you'd need more bounces. Your scene will become slower than. So don't do that! Use FG without ANY bounce, and get your light around with GI (a lot faster!).

Most important thing to know is the RADIUS of your photons. To do this (a working method) turn off FG first.

But before you could even do this, you need a good SPREAD of the photons.

In GI set the max no of sampling on 1 (important value, otherwise you'll get a different type of artefacts: the bright areas would become the overlapping photon-area instead of the photons themselves! and hence you would try to get rid of these in a wrong way making the effect only stronger! - Artifact Understanding = the most important part of getting good lighting in MR)

Anyway: set amount of photons VERY low (3000 or so). And take a (very) SMALL radius to check the 'spread of your photons'. Check for the bounced light, also test with 30K and 300K amount of photons. If the spread is good, keep it, if not: add reflectors, change the photon 'tube' size etc...

If spread is good, up the max sampl no to 500-1000 and adjust your photon radius. Run several test with different sizes (from small to high). As soon as your scene is SMOOTH keep the radius and add FG (presets are ok, and although they look fast, can be tweaked to become even faster!)

 

that's about all you need to know about MR. (use log exp control or mia_exposure_simple)

 

nisus