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View Full Version : mental ray arealight vs portal light


david376
01-11-2013, 02:30 AM
I found the mr area light and portal light behavies very differently.

the left in the picture is an arealight,and its falloff looks much like rectange.

but with a portal light hooked in on the right,the falloff looks like a point light?

Is anybody knows what's behind this?

vital00
01-11-2013, 06:30 PM
what software are you using?

If you are using 3ds max this is normal... but actually, the reverse situation in which you are describing...the right seems much more a area light than a portal light...
Anyways...Jeff Patton talks much of this in his DVD:
http://www.thegnomonworkshop.com/news/2009/09/new-lighting-and-rendering-tutorials-series-by-jeff-patton-2/

Panupat
01-11-2013, 07:46 PM
I think it make sense the way it is. Portal light mimics an opening with light actually shining from the sky far away. While area light act as an actual light source positioned right there. That's why portal light doesn't concentrate any light in the center.

david376
01-12-2013, 07:50 PM
what software are you using?

If you are using 3ds max this is normal... but actually, the reverse situation in which you are describing...the right seems much more a area light than a portal light...
Anyways...Jeff Patton talks much of this in his DVD:
http://www.thegnomonworkshop.com/news/2009/09/new-lighting-and-rendering-tutorials-series-by-jeff-patton-2/

yeah,you are right.I have read that the 3dmax mr has a reverse situation,what made me test in the maya mr.I was using maya 2012,and got a reverse result what is really confusing me.

thank you for your url,that's very helpful,I'm thying to find out what's the reason.

david376
01-12-2013, 08:23 PM
I think it make sense the way it is. Portal light mimics an opening with light actually shining from the sky far away. While area light act as an actual light source positioned right there. That's why portal light doesn't concentrate any light in the center.


thank you for your replay.

But,it comes two different reasults as in maya mr or max mr.It was acturally as you described in 3dmax mental ray,but a reverse reasult in the maya mental ray.

It's so confusing~What does the stand alone version mental ray do I wonder,and what does mental ray want?

Saturn
01-12-2013, 08:52 PM
simply use the portal light. It could be used as a area light without any problem.
Got a better sampling and a more accurate result

david376
01-12-2013, 08:59 PM
simply use the portal light. It could be used as a area light without any problem.
Got a better sampling and a more accurate result

which software are you refering to?As I know,portal light in 3dmax's mental ray has no problem,but not so well in maya's mental ray.

david376
01-12-2013, 10:38 PM
here comes the discussion about the 3dmax arealights.

http://forums.cgsociety.org/showthread.php?f=6&t=999353



And I got the reasult from the video that,in 3dmax mental ray,it's a bug,and use vray instead.

http://www.thegnomonworkshop.com/news/2009/09/new-lighting-and-rendering-tutorials-series-by-jeff-patton-2/



But how comes the maya mental ray's portal light?There must be some problems about the portal light.Look at the pic I posted.

Bitter
01-12-2013, 10:51 PM
This is really a trivial problem that can be solved with another shader to spend all that money on migrating to a different renderer.

The area light shaders is an Autodesk implementation. They are aware of the problem but you can give them more votes on the Maya Feedback board to make these changes.

The integration problems have reached enough of a boiling point that I know it's become a bigger priority. So rather than give up, now is the time to be in the Betas and re-submit the requests.

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