I figured it was time I got my act together and finished off the patch for
pov I was writing. So I'll probably be posting samples occaisionally for the
next little while. Anyway I've implemented two new lighting models to
compliment the diffuse lighting model, Oren-Nayar (Right Teapot) and
Minnaert (Left Teapot). The Oren-Nayar lighting model does a fairly good job
of rendering surfaces that are supposed to appear rough such as clay. The
Minnaert lighting model does a good job of producing an effect similar to
velvet - also handy for metals. Anyway in the images all three teapots have
exactly identical finishes and pigments the only difference is the lighting
model (Left = Minnaert, Middle = Diffuse (POV-Ray Default), Right =
Oren-Nayar). Comments? Suggests? Other lighting models people think I should
add? Oh and there is a tiny little bug in the Oren-Nayar shader which I
should have worked out shortly, and I plan on adding an anisotropic lighting
model as well.

-- 
Kevin
http://www.geocities.com/qsquared_1999/
#macro _(r)#if(r<12)#local i=asc(substr(
"oqshilacefg",r,1))-97;disc{<mod(i,7)-3,
div(i,7)-1,6>,z,.4pigment{rgb 10}}_(r+1)
#end#end _(1)//KL

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Attachments:
Download 'shaders-002.jpg' (52 KB) Download 'shaders-001.jpg' (117 KB)

Preview of image 'shaders-002.jpg'

Preview of image 'shaders-001.jpg'

I'd be interested in hearing simple descriptions of the differences between
these lighting models and the one POV-Ray uses by default.

 - Slime
 [ http://www.slimeland.com/ ]

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The one on the left looks really great! I've always had a really hard time
with lighting. I think there's a lot of room for improvement in POV's
lighting capabilities, and maybe your patch will help...

Regards,
David

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kev### [at] ekoikcom news:3f6ccdf7@news.povray.org

> identical finishes and pigments the only difference is the lighting 
> model (Left = Minnaert, Middle = Diffuse (POV-Ray Default), Right =
> Oren-Nayar). Comments? Suggests? Other lighting models people think I

Interesting, but... wouldn't it be easier to have simillar effect playing 
with finish options, the one to the left - add some specular,  to the right 
- change brilliance and diffuse ?


-- 
#macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
);g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

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> I think there's a lot of room for improvement in POV's
> lighting capabilities

Lets hear them ?

The most important thing I can think of is global illumination. It would be
nice, if it wouldn't flicker in animation, and needed recalculation only
where objects are moving, for example.

Then, there's the patches lying around from previous versions of POV, such
as the blinn highlighting model (a slight improvement over phong highlights)
and there's the extra features from MLpov that can be applied to finishes
(an easy way for specular/reflection maps) along with built-in blurred
reflection. Last but not least: The postprocessing features such as glow
filters.

Apart from this, I think it's a matter of practice. You can optain great
results with POV-Rays lighting capabilities already. Nothing less than
state-of-the-art. But as usually: Faster computers will help.

Regards,
Hugo

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