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On 2/20/21 11:50 AM, Norbert Kern wrote:
...
Another amazing image. I agree with others on the color comp and that
vase. I guess as children you were inside while I was outside working on
the estate grounds :-). Took me a second to recognize the Vermeer - it's
mirrored...
As I suspect, you suspect, given your code comments, what you are seeing
is the normal inversion I was talking some about while fixing the
quilted pattern for povr last fall. Something which happens often enough
when you play with bump sizes above about 0.5. You have only triangles
there - one surface - and when the normal inverts the surfaces turns
inside out(1).
Attached an image. All without the light blocking box. In the top left
your original scene. In the upper right the bump size set at 0.5. In the
lower left a v3.7 render showing the existing v3.7 / v3.8 quilted normal
inverting with a bump size of 5. In the lower right the povr branch's
fixed quilted normal - which does extra work to prevent the
primary/major normal direction from inverting - still with a bump size
of 5.
If you had instead used small boxes with some thickness > the min
intersection depth the shadow test code would likely pick up the
"second" box surface correctly and see the intersection at the first
surface as being in shadow.
(1) - And this touches a POV-Ray secrete with respect to shadows... As
often as not the surface appears to be in shadow because the normal
points away from the light source and so it appears unlit when in fact
POV-Ray considers it lit. The actual shadow detection code usually fails
to correctly pick up the at surface intersection on the shadow test. ;-)
Aside: My guess is that you needed the extreme normals for radiosity to
reasonably light the wall texture? If so, an alternative is to lower the
finish brilliance to something toward 0, so the shading model gives less
than the usual importance to the incidence of the light rays hitting the
wall. This is the purpose of brilliance(2).
(2) - I have in my head there is a brilliance setting in the global
radiosity block with which Christoph was playing in v3.8. I cannot
remember the state of it at the moment. It was, I think, a boolean - if
so, probably as to whether to use the textures finish brilliance setting
if other than 1.0. But..? Not sure what if any implications for
radiosity and finish brilliance with v3.7.
Bill P.
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Attachments:
Download 'nrmlbmpszinvrt.jpg' (54 KB)
Preview of image 'nrmlbmpszinvrt.jpg'
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