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View Full Version : About scene-scale, IES and other things; noob questions.


cltax
08-10-2011, 11:01 AM
Hi guys,

I'm trying to better understand how to set up a scene and use lights efficiently. I always have problems with the setup of the light intensity. Now I'm beginning a series of tests with a cornell box.
I'm using Maya and Vray, but I'll do comparison with Mental Ray too because I'm interested in deepeing this matter.

The first thing that everyone says is about scale, so I scaled my box to 200x200centimetes. In this case I'm using Vray so there are VrayMaterials for the wall and the objects.

I built a rectangular Vray light and set the intensity to 130 Watts, scale of the light is 1, color correction for a linear workflow. Changed nothing else and there's no GI.
But here is the first thing I do not undersand: Vray is supposed to work on correct physical rules, so why the scene is like this ?
In a real room of 2x2m 130watt do not make so much light, at least to my eyes. In Mental Ray I would put an exposure node to deal with it, but is that in Vray too ?

http://img811.imageshack.us/img811/4794/unled1au.jpg
By cltax (http://profile.imageshack.us/user/cltax) at 2011-08-10

cltax
08-10-2011, 10:54 PM
Hi , probably my question is a bit confused, well ... I'm confused. My goal is getting a good idea of what I have to do to get realistic results without always doing 1000 attempts.

So using a IES file everything seems fine, again ... there is no GI yet, no linear workflow, but at least it looks like that scaling and using a IES I can get a good result ... tell me if I'm wrong. Ah ... it's a Vray render

http://img194.imageshack.us/img194/2355/unled1tx.jpg
By cltax (http://profile.imageshack.us/user/cltax) at 2011-08-10

By cltax (http://profile.imageshack.us/user/cltax) at 2011-08-10

cltax
08-10-2011, 11:45 PM
OK so at least I got a point. This is Mental Ray with the same IES file, I used the wom_Archlight shader plugged into a mr_Arealight, multiplyer 1 and everything default; a mr_photometric_exposure to the camera with ISO 200 and F8, the rest default

http://img829.imageshack.us/img829/1899/unled1fr.jpg
By cltax (http://profile.imageshack.us/user/cltax) at 2011-08-10

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