"Michael Andrews" <M.C### [at] readingacuk> wrote in message
news:3BAB71AF.B0F503CA@reading.ac.uk...
> System: POV-Ray for Windows v3.5b2, Windows NT4 sp6, AMD Athlon 1GHz,
> 256 megs SDRam
>
> I know radiosity is considered experimental, but I thought I would
> report my observation.
>
> With recursion_limit 2 or higher a simple ambient sphere in a box
> produces a very strange illumination.
>
> If you run the appended script you will see very distinct vertical and
> horizontal bright bands on the surfaces, of the same width as the
> sphere.
>
> Reducing the error_bound makes the edges of the bands sharper,
> increasing count makes them more even.
>
> Using a single box as the container gives much wider illuminated bands,
> less easy to see.
>
> The script gives an identical result with MegaPov 0.7.

Not a bug, just bad settings; and possibly scene setting too considering
there's a large black emptiness behind the camera.

Try the following:

  radiosity {
    pretrace_start 8/image_width
    pretrace_end   4/image_width
    count 123  // does not need to be as high now
    error_bound 1.6  // higher smoother
    low_error_factor .04 // lower smoother
    nearest_count 3 // lower faster, less quality
    max_sample 4 // ?? higher better ??
    recursion_limit 2 // 3 is really slow, 1 is dimmer
  }

It only seems there's a problem when you muck around with the settings and
get bad ones.  Not easy to get right, which is why leaving all out and
letting defaults be used generally looks okay.  But certainly the recursion
limit isn't faulty.

Bob H.

Post a reply to this message