Jaime Vives Piqueres wrote:


> 
>   Hmmm... this technique gives better results with very reflective 
> textures. I think your shoes are more suited for a clasical setup with 
> area lights and moderate rad settings. 

Yes I expect you are right, partially reflective surfaces are poor 
performers with radiosity, obviously, because you don't have the 
specular component to help show the texture.  So far, I see that low 
reflectivity will still show up the normal, if the hotspot sources are 
directional enough.  HRI obviously gives so encompassing a stimulus that 
the texture gets washed out. That is a vexing thing because the gentle 
shading you can get is hard to give up on.  With a few, very directed 
hotspots, the sense of shadowing then gets a little doubtful, perhaps.

Add too all of this the fact that the optical behavior of finished 
leather is an elusive thing even when you are holding the actual leather 
in your hand!  Of course the other side to that coin is that leather 
comes in such a wide variety of textures.  Something I would exploit in 
my paintings.  Suede was far and away the easiest texture to paint.  If 
the show was really glazed calf, but everyone thought I'd done a 
beautiful job portraying suede,...I took it!  But raytracing is not 
painting.

You can also use a mixed setup,
> creating the spherical map from a scene where you know the lights 
> placement (I've not tried this yet...).
> 

Yes, in fact I was doing extensive testing of just that, and had pretty 
much given up on HDRI until I could understand the effects of 
directionality better.  But since you published your stuff I took a 
little detour ;)  I needed a rest from looking at my little test losenge 
shape anyway, lol.  I was interested the way you had made the image 
pigment a function then applied the poly_wave.   I was testing with 
something much more crude but along similar lines perhaps.  I guess I 
was trying to determine how complex the stimulus could get before 
loosing the effect of normal textures on the subject.

#local NumLights = 8;
#declare BgColor =
pigment { average
   pigment_map {
     #local A=0; #while(A<NumLights)
       #local IntensityFactor = 25+25*rand(S);
       #local F = rand(S);
       #local CVect = <(.4+F*.6),(.1+F*.6),(.5+(1-F)*.5)>; 
 

       #local RVect = <30+(.5-rand(S))*90,0,(.5-rand(S))*90>;

       [ 1 cylindrical
	rotate <RVect.x, RVect.y, RVect.z>
         poly_wave IntensityFactor
         pigment_map{ 

           [0 rgb 0]
           [1 rgb CVector*IntensityFactor]
         }
       ]

     #local A=A+1;#end
   }
}
#declare BgFinish = "ambient 5 diffuse 1"
sphere { 0, 1 hollow
             clipped_by { plane { -y, -.2 } }
             pigment { BgColor }
             finish { Parse_String ( BgFinish ) }
             scale 2000
}

I was also testing with area lights in the hot spots as you meantion. 
But nothing too exciting has emerged so far.

Post a reply to this message