clipka <ano### [at] anonymousorg> wrote:
> Am 10.01.2018 um 11:49 schrieb Motive17:
> > Good morning to all,
> >
> > I'm focusing on a quite strange issue.
> >
> > I have simply defined this light source:
> >
> >     light_source {
> >                  <0,500,-1000>
> >                  color rgb <255, 255, 255>
> >                  fade_distance 1
> >                  fade_power 0
> >                  media_interaction off
> >                  media_attenuation off
> >                      }
> ...
> > The strange issue is relative to the behaviour of the light reflected by the
> > cylinder. It seems to increase when I increase the distance between object and
> > light source. Why? There is any light attenuation defined.
>
> If you move the light source in the z direction only, then as you
> increase the distance, the direction of the light source is getting
> closer and closer to -z, so the light source gets closer and closer to
> being perpendicular to the cylinder's axis.
>
> Thus the lit portion of the cylinder is illuminated more vertically
> (with respect to the cylinder surface, not the "world").
>
> The diffuse component of a surface becomes brighter as the surface is
> illuminated more vertically.
>
> If it was just a matter of direction, this would be perfectly realistic.
>
>
> In real life, the illumination from a light source also gets dimmer as
> the distance increases. To simulate this properly, you should use
> `fade_power 2`.

Thank you for the reply.
I think you convinced me...

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