In article <402AF54C.508F9AE8@pacbell.net>, Ken <tyl### [at] pacbellnet> 
wrote:

> It would really help if you could provide a short example of the code
> you are working with that would illustrate the problem and thus help
> us isolate it for you.

Ken,

Thanks.  I'm sorry it's taken so long to get back to this, but, you 
know, POV sort of gets squeezed into the cracks of my life, not vice 
versa.  

I've posted a couple of images over on p.binaries.images that illustrate 
what I'm talking about.  I'm modeling a starship, and when I do the 
superstructure paint as a y-gradient pigment, thus:

#declare t_Layers = texture {
   pigment {
      gradient y
      scale 2.26
         pigment_map {
            [0.0 p_trek_31 ]
            [0.90 p_trek_31 ]
            [0.90 p_trek_30 ]
            [0.999 p_trek_30 ]
            [0.999 p_trek_31 ]
            }
         } // close pigment
         
      }; //close texture t_layers

(using Jeff Lee's Trek pigments, which he was very kind about sharing), 
in the front orthographic view, the image comes out fine.  (Figure 1).  
You can see that the structure goes up further than the pigment in 
question, btw, which becomes important in a moment.

The front view (figure 1) uses an orthographic camera set up as follows:

camera { 
   orthographic
   location <0, 10, 175>
   look_at  <0, 10, 0>
   up <0, 0, 85>
   right <255, 0, 0>
   }

Everything looks fine.  But then, when I render my top view (figure 2), 
the y-gradient pigment vanishes, and you can see the inside of the hull.  
(The darker grey lines are the 'inside' of the structure which projects 
from the bottom of the hull.  It took me a while to figure out what I 
was looking at, there. 8) )

The top view (figure 2) uses an orthagraphic camera set up as follows:

camera { 
   orthographic
   location <0, 60, 0>
   look_at  <0, 0, 0>
   right <255, 0, 0>
   up <0, 382.5, 0>
   }

The other pigment in the y-gradient still appears, which puzzles the 
heck out of me.  Also, the superstructure's top element, which is not 
gradient textured, still appears, which tells me that I haven't set the 
camera too close to the model.  (I made that mistake on a previous 
model, and couldn't figure out for the longest time where the back end 
of the nacelles had gone, or why changing the light levels didn't change 
what I was seeing. *^.^* )

When I make a one-tenth unit adjustment to the position of the camera, 
setting it up like this:

camera { 
   orthographic
   location <0.1, 60, 0.1>
   look_at  <0, 0, 0>
   right <255, 0, 0>
   up <0, 382.5, 0>
   }

I get figure 3, in which the pigment is back, but the angle is kind of 
odd.

Why does it do that, and how can I make it stop?

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