Hi,

I was curious as to whether there were any plans for including something
like the Blinn reflection model in POV-Ray:

http://www.siggraph.org/education/materials/HyperGraph/illumin/specular_high
lights/blinn_model_for_specular_reflect_1.htm

The reason I ask is I'm looking for a way to accurately render from a
distance a surface ( basically a height field ) consisting entirely of
rectangular legos.  A 'distance' means that in a given frame of an animation
there would be more lego parts on the surface than pixels in the rendered
frame, and enough legos that modelling each lego explicitly with CSG would
be prohibitively expensive in terms of memory use.

The alternative is to try to apply a finish to the height field that
simulates how the blocky, bumpy lego texture would behave: some light in a
given ray would bounce off the facets on the sides or tops of the lego
bumps, and some would bounce off one of the sides of the main rectangular
component.  Some of the reflected rays would be occluded by bumps, or by
other legos, at certain camera and light source angles.

The blinn model allows simulation of this via a (relatively) simple
equation, where the statistical distribution of facet normals, degree of
occlusion, and fresnel reflective properties are quantified.

First, am I overlooking some easier way to do this?  Second, would a patch
to POV 3.1 to add support for the blinn model be a welcome thing (I am on
linux right now and there doesn't seem to be an easily acessible 3.5 version
for linux at the moment)

Thanks

Brian Dunstan

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On Fri, 14 Dec 2001 04:36:32 -0500, "Brian Dunstan" <bkd### [at] cornelledu> wrote:
>Hi,
>
> I was curious as to whether there were any plans for including something
> like the Blinn reflection model in POV-Ray

IIRC The blinn highlighting model (is it the same?) was part of patched POV
called MegaPOV ( http://nathan.kopp.com/patched.htm ). IIRC there were some
description (probably in povray.unofficial-patches) why it is not ported into
official 3.5 but I'm sure it was considered.

ABX
--
#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
function{_(x-2,y,1)&_((x+y)*.7,z,.1)&_((x+y+2)*.7,z,.1)&_(x/2+y*.8+1.5,z,.1)}
contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35

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> IIRC The blinn highlighting model (is it the same?) was part of patched
POV
> called MegaPOV ( http://nathan.kopp.com/patched.htm ).

It was included in MegaPOV by Nathan Kopp at my insistance. (After I
provided him with a good explanation of the model.)

> IIRC there were some
> description (probably in povray.unofficial-patches) why it is not ported
into
> official 3.5 but I'm sure it was considered.

I'll have to look that up. I was not entirely sure why it was not in. I
usually respect the Team's decisions in this regard and keep my mouth shut.
Although I must say I was disappointed.

Post a reply to this message

In article <3c1b8a34@news.povray.org> , "Tony[B]" <ben### [at] catholicorg> 
wrote:

>> IIRC The blinn highlighting model (is it the same?) was part of patched
> POV
>> called MegaPOV ( http://nathan.kopp.com/patched.htm ).
>
> It was included in MegaPOV by Nathan Kopp at my insistance. (After I
> provided him with a good explanation of the model.)
>
>> IIRC there were some
>> description (probably in povray.unofficial-patches) why it is not ported
> into
>> official 3.5 but I'm sure it was considered.
>
> I'll have to look that up. I was not entirely sure why it was not in. I
> usually respect the Team's decisions in this regard and keep my mouth shut.
> Although I must say I was disappointed.

I think it was because a more general solution is needed to the whole issue
of different models, but I am not really sure.  It may just have been some
of the common other reasons why it isn't in...

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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