|
 |
Hello.
I decided to do some simple scenes to teach myself learn how to use lights a
bit more creatively - instead of just my usual main light, fill light and
'just below the camera' light.
After enclosing a light in a sphere which had a filtered color_map applied
to it, I came across the peculiar effect in this image. It only seems to be
the granite pattern that has this effect on the lighting.
This image was rendered using MegaPOV v0.5a, but it's not a bug as the
official v3.1g renders the same image.
I've posted the scene-file in povray.text.scene-files if anyone wants a
look.
Alan.
Post a reply to this message
Attachments:
Download 'granite_light.jpg' (49 KB)
Preview of image 'granite_light.jpg'
|
|
|
|
Alan wrote:
> After enclosing a light in a sphere which had a filtered color_map applied
> to it, I came across the peculiar effect in this image. It only seems to be
> the granite pattern that has this effect on the lighting.
Bug or no, it's beautiful!
Simon
Post a reply to this message
|
|
|
|
Wasn't it Alan who wrote:
>Hello.
>
>I decided to do some simple scenes to teach myself learn how to use lights a
>bit more creatively - instead of just my usual main light, fill light and
>'just below the camera' light.
>
>After enclosing a light in a sphere which had a filtered color_map applied
>to it, I came across the peculiar effect in this image. It only seems to be
>the granite pattern that has this effect on the lighting.
Similar effects happen with different patterns, but there's a
relationship between the type of pattern, the distance to the light
source, and the "scale" that you apply.
E.g. if you replace "granite" with "bozo", the effect occurs at about 3
times the distance [#declare lite=<-50,50,-25>*3;].
I guess that it might be caused by rounding errors in the floating point
arithmetic. The geometry of this scene is such that any arithmetic error
will be enormously magnified. I guess that the rounding errors might be
being magnified by something like
(distance to light)^2 / (scale * radius of shadow sphere)
so you'd need the floating point arithmetic to be consistently accurate
to 6 figures to get a correct image in your example.
You can get errors in just about anything in POV if you arrange the
geometry in a sufficiently extreme manner. E.g. if you have a granite
pigment that's scaled by a factor "A", and you place the camera "A"
units away, then you'd expect the rendered image to look pretty much the
same whatever value you give to "A". That's true for sensible values
like "1.0" and "0.01", but if you try "0.0001" it looks completely
different.
--
Mike Williams
Gentleman of Leisure
Post a reply to this message
|
|
