The following scene gives quite different reflections in the official pov3.1g and
versions of MegaPOV. I tried PvMegaPOV 0.7 and MpovPlus 0.5, they both gave the
different rendering from the official. I posted them in p.b.i.

I don't know exactly which result is the more realistic one. Though I would like
to know why there is this difference. Megapov also takes 3 times longer to render
and reports much more reflections in the stats.

- Micha

// begin code

#include "glass.inc"
#include "colors.inc"

global_settings{max_trace_level 50 adc_bailout 1/32}

camera
{
location <0,2,-3>
look_at <0,0,1.>
}

light_source
{  0,  color 1
  translate <1,2.5,-2>
}

cylinder{0,<0,1,0>,1
texture{
        pigment { color rgbf <0.98, 0., 0., 0.9> }
        finish {
                diffuse 0.2
                reflection 0.5
                specular 0.8
                roughness 0.003
                }
        }
interior{I_Glass}
}

// end code

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Micha Riser <mri### [at] gmxnet> wrote:
: Megapov also takes 3 times longer to render
: and reports much more reflections in the stats.

: global_settings{max_trace_level 50 adc_bailout 1/32}

  It occurred to me that could it be that megapov, for some strange reason,
behaves differently with the adc_bailout value than pov3.1 does.
  The number of reflections and larger rendering time would indicate that,
eg. that megapov actually ignores the adc_bailout or somehow else uses
it wrongly. Perhaps some photon mapping code is messing things up?. Just
an idea.

-- 
char*i="b[7FK@`3NB6>B:b3O6>:B:b3O6><`3:;8:6f733:>::b?7B>:>^B>C73;S1";
main(_,c,m){for(m=32;c=*i++-49;c&m?puts(""):m)for(_=(
c/4)&7;putchar(m),_--?m:(_=(1<<(c&3))-1,(m^=3)&3););}    /*- Warp -*/

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Warp wrote:
>   It occurred to me that could it be that megapov, for some strange reason,
> behaves differently with the adc_bailout value than pov3.1 does.

No, it is not the adc_bailout value. If I leave the option away, things get even
worse in MegaPOV while there is not much change in 3.1. If I specify adc_bailout
0 the render time in megapov increases to nearly infinty while 3.1 finishes in
reasonable time.

>   The number of reflections and larger rendering time would indicate that,
> eg. that megapov actually ignores the adc_bailout or somehow else uses
> it wrongly. Perhaps some photon mapping code is messing things up?. Just
> an idea.

As far as I know there have been many changes in the code for reflections to add
the photons and other features. It would be interesting to test the same scene
with older versions of megapov, but unfortunately I don't have them any more.

- Micha

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I've been having similar problems which seem to be related to ior. I havn't
been able to test the scene in  3.1 because it uses megapov features but
with ior enabled render time rockets and even freezes whist without it the
scene renders in minutes.

Mick

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I rendered an image with some blob objects made of metal. I used reflection
type 1 and ior 9 to get fresnel reflection, but I had to kill the render after
57 hours...
The very same scene without metal textures took one hour to render and I don't
think the reflection should have effected the render time so strongly...

Mick Hazelgrove wrote:

> I've been having similar problems which seem to be related to ior. I havn't
> been able to test the scene in  3.1 because it uses megapov features but
> with ior enabled render time rockets and even freezes whist without it the
> scene renders in minutes.
>
> Mick

Post a reply to this message

"Micha Riser" <mri### [at] gmxnet> wrote ...
> The following scene gives quite different reflections in the official
pov3.1g and
> versions of MegaPOV. I tried PvMegaPOV 0.7 and MpovPlus 0.5, they both
gave the
> different rendering from the official. I posted them in p.b.i.

FYI... I should confirm that this is a bug in MegaPov.  It has been there
for a while and causes reflections to be too bright.

-Nathan

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