Correct Area Light sampling in Mental Ray

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  12 December 2012
Correct Area Light sampling in Mental Ray

Hi, I wanted to know what is the best kind of light for area light sampling in mental ray for maya, to get correct area light sampling.
I know portal lights have a good sampling but it has still a stronger intensity near the center.
Which light should I use to get correct sampling, without using brute force fg.
 
  12 December 2012
I don't know what you're trying to do, but it makes sense that the reflection of the area light is brighter in the center (the actual diffuse light isn't brighter). You wouldn't get a uniform reflection from a real life soft box either. In fact, I'd like to be able to texture this reflection to make it even more nonuniform. Guess I'll have to switch to v-ray one of these days...
Anyway, In other aspects the portal light works pretty well.
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  12 December 2012
What's your scene setup? and what are you trying to achieve exactly? Have you got an image of reference for your lighting that you are trying to recreate?
 
  12 December 2012
@lostparanoia: isn't that what the user_ibl_rect is for? (http://materials.mentalimages.com/r...res-list./page2)
 
  12 December 2012
hi n3al, is just cuz with others area light shaders, the light makes a circular like point light shape, indicating stronger intensity near the center.
When it should be like even intensity spread acroos the area of area light.

Thanks tobbew, user_ibl_rect work great.
It seems it has a problem with resolving noise, but it worked great.
 
  12 December 2012
Have you tried unified sampling? Look at this blog http://elementalray.wordpress.com/ .

I don't think you should really have to use that shader for just the highlight (it was for lostparanoias complaint on not being able to texture the highlight), I think checking "use light shape" and using mia_material_x (and no specular highlights for visible area lights) and that way use reflection for the arealights instead should give you your rectangular highlights from the beginning.
 
  01 January 2013
Originally Posted by tobbew: @lostparanoia: isn't that what the user_ibl_rect is for? (http://materials.mentalimages.com/r...res-list./page2)


Ah! I've only recently started using Maya 2013. I didn't know this existed. Thanks for the information!
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"No, the movement is good, it just has to travel faster from spot A to spot B in the same amount of time."
 
  01 January 2013
Have you tried asking an ACI? There is one here in South Africa, named Cobus, he's a wizard with Maya, he helped me a lot with my lighting problems when I was finishing up my studies last year, which is also the year I started 3D.


Here's the link to the website, I think you might need to make an account. These guys on this website will be able to help you. Some of them require you to have Skype or Gtalk, or some other form of instant messaging, this just simplifies everything and they can help you live, you and your instructor will just have to set up a time to connect.

http://pic.autodesk.com
 
  01 January 2013
Originally Posted by tobbew: @lostparanoia: isn't that what the user_ibl_rect is for? (http://materials.mentalimages.com/r...res-list./page2)


Ok, I've tried it out now... It's not quite what I was after. This colors the actual diffuse light as well, which makes the render much grainier and slower. It will certainly come in handy for certain situations, but I'd just like to be able to texture the light's reflection so that it doesn't look like a perfect white square. No real light looks like a perfect white square. I just need to be able to multiply a texture with the light's reflection.
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"No, the movement is good, it just has to travel faster from spot A to spot B in the same amount of time."
 
  01 January 2013
user_ibl_rect is for generating cards using HDRI as stand-ins. You can use it to replicate set lighting if you map the lights to them from the shoot.

However, it's not really meant to be a flat light like an area light for lighting a scene.
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  01 January 2013
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