triangle lit surface......

radiance-general
1

Hi,

I have in trouble with triangle lit surface by light material.
Greg pointed out before that putting light material on the surface is not usual
scene.
However, it works fine to me as long as the surface is rectangle or trapezoid.

When the surface is triangle, some light seems lost.

My scene rad file is like below.

void light triangle
0
0
3 5 5 5

triangle polygon triangle.1
0
0
9 -25 -50 50
    -1 35 95
    10 0 75

I expected 135 lux(illuminance) at the point (0,0,0) with aiming point(0,0,1).
What I got in this scene by running Radiance is 83 lux.

I assumed that the surface with light material distribute light like lambertian
surface.

In the fallowing website, It can be found out that rectangle surface with light
material works fine.

http://www.personal.psu.edu/users/w/x/wxo110/radiance.htm

Any comment will be very helpful to me.

Thanks!

···

From Woogie.

2

See the Radiance book on page 510-512. See also p. 577, sentences 2-3.

Martin Moeck

···

-----Original Message-----
  From: Woogie [mailto:[email protected]]
  Sent: Wed 11/17/2004 4:17 PM
  To: [email protected]
  Cc:
  Subject: [Radiance-general] triangle lit surface......
  
  Hi,
  
  I have in trouble with triangle lit surface by light material.
  Greg pointed out before that putting light material on the surface is not usual
  scene.
  However, it works fine to me as long as the surface is rectangle or trapezoid.
  
  When the surface is triangle, some light seems lost.
  
  My scene rad file is like below.
  
  void light triangle
  0
  0
  3 5 5 5
  
  triangle polygon triangle.1
  0
  0
  9 -25 -50 50
      -1 35 95
      10 0 75
  
  I expected 135 lux(illuminance) at the point (0,0,0) with aiming point(0,0,1).
  What I got in this scene by running Radiance is 83 lux.
  
  I assumed that the surface with light material distribute light like lambertian
  surface.
  
  In the fallowing website, It can be found out that rectangle surface with light
  material works fine.
  
  http://www.personal.psu.edu/users/w/x/wxo110/radiance.htm
  
  Any comment will be very helpful to me.
  
  Thanks!
  
  >From Woogie.
  
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