XM Magdalena 3D print, GGeorgy (3D)
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View Full Version : Broken Area Light behavior in Maya Mental Ray.

Kel Solaar
03-03-2011, 02:06 PM
Hi guys,

I'm encountering some weirdness with Mental Ray Area Lights at the moment, maybe some will be able to shed some light on that !

I did a scene with the following stuff :

Area Light
Area Portal Light
Emissive Plane

The different emitting objects (Area * Lights and Emissive Plane) have the same size and placed above the ground. The reference for me is the the Emissive Plane. Here are some renders now :

Scale 1.0 on emitting objects :

Emissive Plane

Area Portal Light

Area Light

Pretty much the same results, lets move on.

Scale 10 on emitting objects :

Emissive Plane

Area Portal Light

Area Light

Mmmhh Area Light doesn't react as I would expect, I do a quick brainstorming and decide to multiply the intensity by the square of scale (100) in this particular case and here is the picture :

Area Light Tweaked Intensity

Ok we are back in business :) Now I decide to try scaling down, See next post :)


Kel Solaar
03-03-2011, 02:09 PM
Continuing the previous post :

Scale 0.1 on emitting objects :

Emissive Plane

Area Portal Light

Area Light

Area Light seems to do funky stuff again ... I divided my scale by 10 so I'm assuming it will follow the same behavior than when I scaled up, so I multiply my intensity by square of 0.1 (0.01) And here we go :

Area Light Intensity Tweak

Cool I don't see anything now ... Wtf? :) I decide to crank up the intensity a bit to see what's going on inputing 0.1:

Area Light Intensity Tweak Alternate

??? What's happening with the decay ? It seems to cover a larger area than expected.

So basically, has somebody a solution for this ? The problem I have with the portal light, is that it reacts to FG, and can't use a disc shape if I'm right. The scene is attached to the first post.


03-04-2011, 04:43 AM
Simply turn off the FG interaction in your Portal Light. If that's not good enough, use the miFinalGatherHide attribute on your Portal Light.

Kel Solaar
03-05-2011, 03:26 PM
Thank you Sho,

I'll give a try at this, though my main concern is more about the Area Light itself :)


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03-05-2011, 03:27 PM
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