Radiosity seems to work wrong when used with very-small-angle perspective 
camera.

Such camera can be used to simulated ortographics one, like

camera { angle 45/X  location 10*X }  with X = 10000;
  instread of
camera { ortographics angle 45 location 10 }

When using such camera radiosity gets very strongly distored.
Only using extremly low minimum_reuse can partialy prevent that from 
happening.

IMHO that could indicate that either there is a lost-precission problem, 
or, despite what documentation states, minimum_reuse is based on angle 
(like - each sample per 1 degree) not on pixels.

Rendered images and minimal code is on
http://www.raf256.com/povray/bug/radiosity-orthographic/


And below + on p.b.i

Change SHOW_BUG to see good version, bug, and partial fix.


// bug (problem) while immitating orthographic camera by 
// standard-perspectiver camera with very narrow angle
// suggested:  +w640 +h480 +a0.03 +am2 +r2 +fn

#declare SHOW_BUG = 1; // 0=normal 1=show bug  2=show bug + partialy fix

union {
  box { -100, +100 pigment { rgb 1 }  }
  box { <-80,-80,+150> <+80,+80,0> pigment { rgb <1,0,0> } }
  finish { ambient 0 }
}  

camera {
  #local FlatPerspective = 1.0;
  #if (SHOW_BUG)
    #local FlatPerspective = 5000.0;
  #else
    orthographic
  #end 
  up y  right x*(image_width/image_height)
  angle 60/FlatPerspective
  location 250*FlatPerspective
  look_at 0
}  

light_source { <500,2000,1000> rgb 1 }
                                                                          
global_settings { radiosity { 
    count 1600 error_bound 0.3 nearest_count 15  // very-high quality
    //count  800 error_bound 0.6 nearest_count 12 // high quality
    #if (SHOW_BUG=2)
      minimum_reuse 0.000001 
    #end
} }    





-- 
http://www.raf256.com/3d/
Rafal Maj 'Raf256', home page - http://www.raf256.com/me/
Computer Graphics

Post a reply to this message