Ken <tyl### [at] pacbellnet> wrote:
> That is what I suspected but there is still something not quite right in
the explanation. If it
> were a reflection of sort the pattern where it intersects
> the y axis plane should be a mirror of the z axis plane. Instead I am
seeing
> a contiguous pattern emerging that defies the explanation you are giving.
> I am sure it has much to do with the parallel rays of the camera type but
> I am expecting different results. The wall as you put it is the plane with
> the pattern applied to it and the "floor" has a simple white pigment
attached
> to it with it's own finish statement. Oh well back to the perspective
camera :)

You are indeed seeing the continuation of the wall pattern below the floor
plane - I said it *looks* like a reflection, because of the slightly darker
shading.  If you reduce the ambient value of your wall texture you'll see
the lower section is completely in the shadow of the floor plane.  The
difference is that the perspective camera traces rays from a single point,
whereas the orthographic camera traces the rays from a rectangle.  This
means the floor plane actually intersects the camera, allowing you to see
both above and below it at the same time.  You can achieve the same effect
with the perspective camera by intersecting it with the floor plane, eg.
camera {location <0, -1.5, -6.5>}, because once again the rays won't
actually hit the plane, making it invisible.

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