Mental Ray interior blotches

[Daylight]

Hi,

maybe someone could help me. I´ve rendered this room with MR.

I used MR material with DGS & Photon Basic base for the wall and ceilling border.

Everytime, I´ll get this blotches on the border line at the ceilling and some light reflections on the wall.

Increaseing FG doesn´t work enough. I gave it up with FG 6000!

Can it be the material or the light setting?

What I´m doing wrong? Have anyone some ideas to get this problem solved?

Thanks for replys.

Jens

 

[DavidR]

I'm not an advanced mr user (I use Vray), but it looks to me as if your FG radius is too big or your GI radius is too big and Fg is averaging it, giving you the bright corners you call 'reflections'. 6000 is really high for FG, but it means nothing if your GI samples are too low and any samples are too big. If you're in inches, try smaller values like 2" and see what happens. If you're still having problems after that, try VRay

[Thiago de Andrade]

Your final gather samples are way too high. If you're using the latest version of MR (which comes with MAX8) yoú should set the FG samples to less than a 100, and then, just then increase it little by little. I'd start with 20 to 40 in this room, also set its radius to max 2 and minimun 0,2. The larger the radius the lower the render times, the lower the radius the grater the samples must be to achieve fine results, and thus increased render times. Try to render this scene without GI, just FG. If you're not satisfied start with low settings to GI as well. I used to get those blotches when I set the GI fairly wrong.

 

Good luck, and keep posting.

[Daylight]

Thanks for your replys.

I´ll accept your advice and try to make better settings like you said.

I´m still trying to get better results. If it works I´ll post it.

I´m sure your tips will help me!

[Daylight]

Hi,

I´m sorry not to keep the posting on. But know I´m back!

Too much other things to do.

I´ve made some tests and I think I´m coming near get the problem solved.

But I don´t get to the point!

I´ve post some previews.

The first image is rendered with GI 500 and FG 500, r 4000.

I know r 4000 is to big. I´ve got big bright blotches and I´m losing details.

The second image is rendered with GI 500 and FG 40, r 20.

The third image is rendered with GI 500 and Fg 40, r 0.2. Looks better but the blochtes still there. I can´t get it clean!

What do you think?

[Justin Hunt]

For your GI, what are oyur light settings? Dont use the automatic, use manual instead, gives more control

 

JHV

[Daylight]

Here it is!

[Justin Hunt]

Up the max samples to 1000 and average GI phtons to 100000

 

Use 1 or 2 FG bounces, it subtle but worth it.

 

Your render times will go up but the results should be better.

 

JHV

[Daylight]

At time I am totally helpless.

I´ve tried so many things and I don´t get the desired quality.

I´ve tried to adjust the GI settings (with all kind of radius settings) without FG. FG alone (no GI). Both together. Change standard mat. to MR mat. (photon map). Change lights from Photometric area (pic 5) to MR area Omni (pic 4).

Change settings in the MR manual settings rollout.....

A lot of things!

I can´t belive that nobody else have similar problems with those artefacts.

Maybe someone have new ideas for me?

 

I put some images in their for documentation.

 

Mfg jens

[noi-pi]

Hi,

 

I'll try to give some helping hand here...

Try these settings:

 

For GI:

Max Num. Photons per Sample ----> 50,000

Uncheck Sampling Radius.

Trace depth all in values of 5.

 

Light Properties:

Average GI Photons per Light -----> 5,000 (the higher you get the slower)

Global Energy Multiplier -----------> 2.0 ( can be default to 1)

Decay ---------------------------> 1.75 ( lower values greater color bleeds)

 

 

For FG:

Samples -------------------------> 50 (the higher you get the slower)

Uncheck Radius.

Trace Depth Values all to 5. (the higher the bounce the slower)

 

 

 

Use mr Area Spot (Light cone to Rectangle encompassing the opening).

 

 

Almost always these settings where of standard.

I use Meters BTW.

[Daylight]

Hi noi pi,

I´ve used your settings and these are my results.

It must be a basic fault.

I will try harder, I know this problem could be solved!!

 

Thanks for your quick answer.

 

Mfg Jens

[Justin Hunt]

Go highter in your FG samples, its clear that they are too low. Something that I have just come across is to change the FG radius samples to Pixels. As this is a still image then the samples can be concentrated according to the render resolution and not to the room size.

 

Check out this link for more info on MR GI. It is writen for Maya but the concepts are the same http://www.jupiter-jazz.com/wordpress/wp-content/data/tr4kv2/html/index.html

 

JHV

[Daylight]

Thanks Justin, I will go over it!

Mfg Jens