mental ray message window

[Daylight]

Hi,

everytime I do my rendering, the mental ray messages window opens.

I´cant deal with those informatons.

Does anybody know where I can find some information about this messages so I can correct my settings.

At time the message says:"no photons stored after emitting 10000 photons".

Thanks for help.

[pixelperfectg]

If you think of photons as particles and light sources as particle emitters...it helps to resolve these photon errors.

 

There are mainly two reasons for Mental Ray to generate that error:

 

1) The majority of the photons aren't hitting anything. An example of this would be if you used an omni light for the sun. An omni light is basically 6 spotlights put together. Therefore you're shooting photons in all directions. Most of them never hit anything, thus creating the no photons stored error.

 

You can always put an inverted sphere (or box) around your scene to stop these "runaway" photons and the error will go away...but that's not really an efficient way of working with photons.

 

2) The materials you used are not setup to handle photons. This mainly comes into play when caustics are enabled. IE the photons need to pass through an object (such as glass). The physics-phen materials are setup to handle any photon situation. However, if you used the glass(lume) shader and didn't add anything to the photon map slot....then the material won't know what to do with the photons.....presto blammo...no photons stored error.

 

I have an older MR caustics tutorial that describes this better:

http://jeffpatton.net/MR-Caustics101.htm

 

Hopefully, this info will give you a better understanding of why MR generates the no photons stored error.

 

Jeff

[Daylight]

Hi Jeff,

thanks for the quick reply.

That really helps and by the time I´ll check all your nice tutorials to find a good way to handle with MR.

At first I´ve put a sphere around the scene. The error messages stops.

Thanks for that.

As base material I´ve used a max standard. In my opinion it should not cause any problems. Maby I´m wrong.

Now I´ll try to put some MR materials into the scene.

I used for the floor a mental ray mat. with a DGS mat. in the diffuse slot.

It works pretty good but if give the shiny scrollbutton 3 Points I´ll get small light blotches on the ground like an orange.

Is my sample range not high enough? Or I have to make the right settings in Material Editor?

 

Jens

[pixelperfectg]

You should post a render because it's very difficult to guess at what's going on without some visual reference.

[Daylight]

Hi Jeff,

here are my visual references.

The first pic shows on the floor a mr mat. in the surface slot a DGS-mat. with diffuse mapping, shiny parameter is on 3. Photon slot a DGS mat. too.

What can it be?

In second pic I´ve used log exp. control. For my customer I´ve erased some details on the banners.

My big problem is, if I´m using log exp. it will always wash out my textures.

Everbody says, to control this with the mat. editor (bitmap parameters RGB-Level).

But that is not very accurate, if I have to consider the CI from my customers.

The first pic is rendered without log. exp. The map is another one, but it shows the right colors.

 

Jens