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In POVRay, if using a spotlight, the shadows are perfectly defined. We
all know in real life this doesn't happen, due to the diffraction of
light as it passes an interface between two media. Of course, POVRay
deals with the particular nature of light, not the wave nature, so how
do we get it to blur shadows according t distance from casting object
without resorting to area lights?
Cheers,
James Jackson.
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> In POVRay, if using a spotlight, the shadows are perfectly defined. We
> all know in real life this doesn't happen, due to the diffraction of
> light as it passes an interface between two media. Of course, POVRay
> deals with the particular nature of light, not the wave nature, so how
> do we get it to blur shadows according t distance from casting object
> without resorting to area lights?
area_lights?
--
#local T=text{ttf"timrom.ttf""Simon Adameit".01,0}#local Y=1;#while(Y>-1)
#local X=0;#while(X<7)#local O=trace(T<X,Y><X,Y>+z);cylinder{<X-3,Y,5>*.01
<X-3,Y,5>*.01+5e-3,5e-5pigment{rgb 25*O}}#debug chr(83-(O.x=0)*51)#local
X=X+.05;#end#debug"\n"#local Y=Y-.05;#end
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Maybe you don't know, but you cann use the area_light-feature still with
spotlights ...
if you wan't really real shadows and lighting, you need to apply really
good radiosity, and need much RAM, time and a good processor ... (and much
trial and error) ...
I'd suggest using a spotlight and giving it an area_light with "orient" and
jitter ...
--
"Somehow what you suggest is like suggesting to add drills \ jan### [at] lzer net
to cars so you can drill for oil when you run out of fuel. \
Sure you could do it, but it might not be the most practical > Jan
solution." [Thorsten Froehlich in p.u.p] / Walzer
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In article <3C3### [at] jamesjacksoninfo>,
James Jackson <jam### [at] jamesjacksoninfo> wrote:
> In POVRay, if using a spotlight, the shadows are perfectly defined. We
> all know in real life this doesn't happen, due to the diffraction of
> light as it passes an interface between two media. Of course, POVRay
> deals with the particular nature of light, not the wave nature, so how
> do we get it to blur shadows according t distance from casting object
> without resorting to area lights?
Area lights are really the best way to do it, why are you trying to
avoid them?
In reality, there are no true point sources anyway.
--
--
Christopher James Huff <chr### [at] maccom>
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> In POVRay, if using a spotlight, the shadows are perfectly defined. We
> all know in real life this doesn't happen, due to the diffraction of
> light as it passes an interface between two media. Of course, POVRay
> deals with the particular nature of light, not the wave nature, so how
> do we get it to blur shadows according t distance from casting object
> without resorting to area lights?
>
> Cheers,
> James Jackson.
Well, I'd hate to get all technical on you here but...
First, as the others have said, use an area_light - read the docs for a
decent discussion on how to get good shadows.
Second, diffraction is caused by light passing through a finite space
(waves perfectly retain their shape only when completely unobstructed),
for example a thin slit (causes the emergent light to spread out) or
passing "round" an obstruction (causes the light to bend "round" the
object). I think you're getting confused with refraction here - the
changing of the direction of light at an interface - something
completely different which POV handles admirably nonetheless.
Third (and I'm being pedantic here :-) I think POV deals with the *ray*
nature of light rather than waves or particles. Waves have horrible
things like diffraction to cope with, and particles are subject to the
messy laws of quantum mechanics.
But area_lights avoid all this nonsense...
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