Problems with Rectangular Photometric Light

[adamantine]

Hello,

 

I have a bit of question with 3dsmax photometric light with rectangle shape (emit light from rectangle). I'm using 3dsmax design 2010.

 

Unlike the fact that it is supposed to be "photometric light emitting light from rectangle shape", when rendered, the light still came from a single point, which is the center of the rectangle. I have attached some images to help you imagine what I am trying to do. I would like to render an upfiring hanging light fixture, but as you can see on the rendering the light appears to be coming from a single point, not from the rectangle shape as it is supposed to be.

 

Any clue?

 

Thanks!

[chubby_bear]

Hey. Did you ever get this problem solved? I have same issue. Photometric lights have a localized circular hotspot, even if you switch to Uniform Diffuse and make the area light a huge rectangle or a huge circle. It seems like everyone should be having this problem.

 

Thanks.

[Justin Hunt]

this has been an issue for sometime, There are several work-rounds

 

1)If your using Mentalray, use a portal-light with a mr_Blackbody shader.

2)Apply a self-illuminating A&D shader and tell it to emit final gather rays

3)If your using Vray, use a Vray light

 

jhv

[chubby_bear]

Thanks, Justin. Will do.

[Justin Hunt]

woops, I forgot to say apply the Self-Illuminating A&D to a flat plane:)

 

Also bear in mind that if you go down this route, you'll have to increase the FG density and or number of FG samples. Long thin planes dont always play nice and could cause bloches if there are not enough samples to work with

 

jhv

[chubby_bear]

Thanks. I have the blackbody shader working. Is there a way to hide the portal, or will it always be visible in the render?

[SreckoM]

this has been an issue for sometime, There are several work-rounds

 

1)If your using Mentalray, use a portal-light with a mr_Blackbody shader.

2)Apply a self-illuminating A&D shader and tell it to emit final gather rays

3)If your using Vray, use a Vray light

 

Can you explain better this first step?

I can not even find blackbody shader ....

[Justin Hunt]

If you tell the light to be inviable it should not be seen

 

The blackbody shader is hidden by default. You have to make a few changes to a couple of .mi shaders that ship with max. If you do a google search for either Jeff Patton or Master Zap they give a detailed step by step process to do this.

 

jhv