I have imported a scene from Maya 6.5.
I was planning on rendering with GI (Mental Ray), but when I turn on GI in my Render Globals and emit photons from my light (spotlight) the 'Global Illum Photons' option is greyed out. I can adjust the 'Intensity' and 'Exponent' in the attribute editor, but no dice with 'Global Illum Photons' (which is set at only 10000).

Any ides on why?

I found that I am able to adjust the setting manually in the Script Editor with this:

setAttr "spotLight1.globIllPhotons" X;

where X = the number of photons desired.


I still want to unlock the option in the Attribute Editor if anyone has any ideas.

**This has happened on 4 different machines with 2 different files (both imported from Maya 6.5)**

try unloading and reloading mr!

Or even openeing a empty maya them load mr then import teh old scene.

Tried that - I even tried exporting my scene elements as .obj, and importing them to a new scene.

Good idea with un/reloading MR. T'll try that and repost..

Thanks.

OK, while I did not try un/reloading Mental Ray, I did start with a fresh boot of Maya (after a machine restart). I made a new scene, and from there I made a point light, enabled photon emission & (as expected) was able to freely use the dialogue box for Global Illum Photons.

Then I imported the .mb scene, and all seems well.

When I was importing before, I did shut down Maya and restart, but I did not restart my machine (perhaps something was cached somewhere).

Anyhoo.. I am rendering away with ease now.

-Thanks for the suggestions!

I know this is about 6 years late, but there doesn't seem to be a lot of posts on the web (when searching via Google) on fixing this. I'm going to post the solution I posted on CreativeCOW.

This has been a bug since Maya 2009 (that I know of, but judging from the posts here it seems to have been around for much longer than that). Autodesk should REALLY start looking into fixing this because this *STILL* happens in Maya 2013.

These instructions refer to tabs available from Maya 2009 and onwards. Earlier versions of Maya could use the same steps but the options will just be found in slightly different places. Sorry, but I don't have Maya 2008 or earlier to go and check what they are.

1) Start by enable "Emit Photons" for the light under it's mental ray rollout in the Attribute Editor. Notice how the Caustics and GI Photon boxes are greyed out. Go to your render settings, and under the Indirect Lighting tab, enable your GI and/or Caustics. You will see in the Attribute Editor that the photons boxes are still greyed out. Untick and tick the Emit Photons checkbox for the light again. The relevant photon boxes should now not be greyed out anymore.

***HOWEVER***

I have just run into a similar problem on a friend of mine's scene where this solution didn't work. Why, I don't know. It seems like there's something very specific in that scene that caused it. The solution to fix that is to do the following:

2) Close Maya (if you had it open) and start Maya. In a blank scene create a new light. Follow the steps above so that the photon boxes are not greyed out anymore. Once the boxes are not greyed out, IMPORT your scene with the faulty lights into this blank scene with the one working light. All those lights that had their photon boxes greyed out *SHOULD* be working now. Save your file as with a different file name than the original one you imported in case you need to go back to your old file. That is it! Any lights you create from this point onwards *SHOULD* have the relevant photon boxes ungreyed out.

They will never actually fix these problems. You see the thing is as a buyer, or potential user fixing small glitches would be good. But as the institutional buyer or your boss the viewpoint is different, whet do they care if it makes your life harder. They will ask what the benefit is for them so priority shifts to cool new marketable features.

Fixing something that should never have been wrong in the first place is not marketable.

Maya has loads of unfixed problem that have been there since who know how long, all applications are like that. 3dsMax, photoshop, firefox, chrme, ie you name it. Its a fact of life.