POV-Ray : Newsgroups : povray.advanced-users : Radiosity rendering depends on camera direction? : Re: Radiosity rendering depends on camera direction? Server Time: 17 Jun 2019 12:35:56 GMT
  Re: Radiosity rendering depends on camera direction?  
From: Tamas Gunda
Date: 7 Apr 2019 13:30:00
Alain <kua### [at] videotronca> wrote:
> Strange, radiosity have no effect of the geometry and should be
> independent of the camera's location and orientation.
>
> What can happen is a difference on what areas radiosity is sampling. If
> that's the case, increasing the count value should help, also, using the
> two values variant often help :
> count 175 25000
>
> You may also want to reduce the value for pretrace_end. Default is 0.04.
> Try 0.01, 0.005 or 0.0025.
>
> Looking at the dark end and you really need more samples. Quadrupling
> your count value may not be quite enough. You may also need to increase
> the recursion_limit value to 4 or maybe 5. Also, reducing minimum_reuse
> could also help. Default is 0.015. Try 0.01 down to 0.004.
>
> Adding some roundness to the edges can do a lot in reducing the
> artefacts in the darker areas. A clipped cylinder will do the trick.
>
> If you can post the source of your scene, it'll be easier to diagnose
> the issue and help you.
>
>
>
> Alain

Thanks for the reply. Well, I tried sytematically many variations. It helped to
decrease the artefacts, however, the main problem could not be solved. It is
mostly influenced when playing with the radiosity brightness and finish/diffuse
values of the walls, but the effect of a given setting is different on the
different faces. Inspect www.gunda.hu/cube/povray again: In the third picture
some of the differences between the cube sides disappeared (the upper and the
right), while others became stronger. In other words, it seems to me that nearly
every setting influences more or less the brightness of the generated pictures,
and this influence depends somehow on the direction of the camera.


The radiosity settings used:

#if (radio)
 global_settings {
    ambient_light 0
    radiosity {
      pretrace_start  64/image_width
      pretrace_end    4/image_width  //8
      count 250 25000  //150
      nearest_count 10 //
      error_bound 0.33 //0.5
      recursion_limit 4 //3
      low_error_factor 0.5  //0.5
      gray_threshold 0.5  //0.5
      minimum_reuse 0.004 //0.025
      maximum_reuse 0.2 //0.2
      brightness 1.3 //1.5
      adc_bailout 0.01 //0.01
      media m_media
      //max_sample 1
      //normal on
    }
  }

#else
 global_settings {ambient_light .1}

#end


Tamas


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