Image Based Lighting not working correctly

[alphajoe]

I am having a problem getting IBL to work correctly in Maya. I am loading one of the hdr files from debevec and using it as the image file in the IBL node. when I render, I can see the environment with no problem, but the objects in my scene are full white. Is there a control somewhere that will let me control how bright the light is coming from the IBL node? I have tried reducing the color gain, but that also darkens the environment, and it still renders very bright.

If I turn off emit light, all of the objects in my scene render full black, except for the environment.

I have also tried it with and without FG and GI.

[mandrak]

try to decrease Irradiance Color attribute in shader's mental ray section.

[wildcat]

I have an answer (?) and a question.
The best thing you can do is to use the RayType plugin by Horvath Szabolcs, it gives you full control over FG, photon, light, eye, shadow, custom rays and more. It's a simple and great plugin.

The question is:
Did anybody get IBL working in Photon mode? I tried both combined with "emit light" and photon only, with and without FG, with and without RayType filtering, and I always get weird results. Eg. I tried with a simple torus on a plane, both with a grey lambert (not the initial SG, for security), lightened by a HDR texture network. When I turn on "Emit photon" the torus gets full white and lightens the plane, which has the same material but seem to get much less light than the torus.
In addition: when I turn off "emit light" and use only FG to lighten the scene, the objets get much darker and all blueish. My HDR imge is a clean sky with a very bright sun, and in this case it looks like mental ray is treating the HDR image as a normal RGB image, where the blue color gives the most light.
Anyone else got such features with IBL? Is it buggy? Or just tricky to use? Or (always leave a third choice) am I dumb?

[joojaa]

Your photon energy values are too high. Drop it down, the value dopends on the size of your scene.

And no mr does not consider the white as non hdr its just that most hdr images ive seen have clipped the suns value down form what it actualy is, so thet they dont destroy their cameras, Second fg works with sampling and it might miss the sun entirely (a thousand samples is realy very coarse).

Then incomes gamma wich need to be adjusted too since your monitor isnt linear and the hdri IS, oratleas should be tough mnot all sources have done so.

[dutchschultz]

QUOTE(Joojaa @ 01/25/05, 03:00 AM) [snapback]196516[/snapback]
Your photon energy values are too high. Drop it down, the value dopends on the size of your scene.

Where can I set the energy values for photons casted by an IBL? I did not found it.

Thanks.

[nndr]

also I have not understood this.

[sanny]

in the render globals, in the Mr tab, you can change the final gather scale.

I had the same problem when first using the FG with HDR images.