"Rafal 'Raf256' Maj" <spa### [at] raf256com> wrote in message
news:Xns957BCB950ADBAraf256com@203.29.75.35...
> 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
> } }
>
>

just to nitpick before everyone else, is this pov 3.6 or 3.6.1? official
release or custom compile? what operating system?

not that I would know if it is or isn't a bug... just getting the obligatory
system setup questions out of the way.

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