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Hi all,
I was wondering whether someone can explain why this scene renders
differently according to whether the version switch is there or not.
I mean what specifically makes it render so differently?
Regards,
Lutz
// Different texture, according to whether this is on or not
#version 3.1
#declare PreviewTexture =
material
{
texture
{
pigment
{
color rgb <0.66, 0.66, 0.66>
}
normal
{
bumps , -0.5
scale <1.0, 0.001, 0.001>
}
finish
{
ambient 0.3
diffuse 0.7
brilliance 5.0
specular 0.8
roughness 0.1
reflection 0.15
}
}
}
camera { // Camera PreviewCam
location <0.00, -7.50, 3>
direction <0.0, 0.0, 3.00>
sky <0.0, 0.0, 1.0> // Use right handed-system!
up <0.0, 0.0, 1.0> // Where Z is up
right <1.0, 0.0, 0.0>
look_at <0.000, -0.100, 0.000>
}
// ******* L I G H T S *******
light_source { // Light1
<5.820, -8.500, 6.316>
color rgb <1.000, 1.000, 1.000>
}
light_source { // Light1
<5.820, -1.500, 3>
color rgb <0.400, 0.400, 0.400>
}
object {
sphere {<0,0,0>,1}
material {
PreviewTexture
}
hollow
}
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Lutz Kretzschmar wrote:
>
> Hi all,
>
> I was wondering whether someone can explain why this scene renders
> differently according to whether the version switch is there or not.
> I mean what specifically makes it render so differently?
In the docs see - 6.11.10 Noise_generator
v3.5 uses a different default noise generator. The version directive
set to v3.1 causes it to revert to the old noise generator, thus the
difference.
--
Ken Tyler
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On Sat, 12 Oct 2002 22:40:21 -0700, Lutz Kretzschmar <lut### [at] stmuc com>
wrote:
>I was wondering whether someone can explain why this scene renders
>differently according to whether the version switch is there or not.
>I mean what specifically makes it render so differently?
It's the normal. Either the pattern (bumps, which uses different noise
generators) or the non-uniform (anisotropic) scaling, which IIRC is
handled differently in 3.5 due to some bugs in 3.1. Or maybe even
both.
Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG e-mail : pet### [at] tagpovrayorg
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Peter Popov wrote:
>It's the normal. Either the pattern (bumps, which uses different noise
>generators) or the non-uniform (anisotropic) scaling, which IIRC is
>handled differently in 3.5 due to some bugs in 3.1. Or maybe even
>both.
Just curious: in 3.5 the uniform scaling of a normal also scales the bump
height, so that the apparent slope stays the same, right? This far no
problem. But how does it work with non-uniform scaling, that is, how is the
height calculated?
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"Peter Popov" <pet### [at] vipbg> wrote...
> On Sat, 12 Oct 2002 22:40:21 -0700, Lutz Kretzschmar <lut### [at] stmuccom>
> wrote:
>
> >I was wondering whether someone can explain why this scene renders
> >differently according to whether the version switch is there or not.
> >I mean what specifically makes it render so differently?
>
> It's the normal. Either the pattern (bumps, which uses different noise
> generators) or the non-uniform (anisotropic) scaling, which IIRC is
> handled differently in 3.5 due to some bugs in 3.1. Or maybe even
> both.
It probably is related to the way that normals are scaled differently in POV
3.5 compared to POV 3.1. I haven't rendered your scene, so I can't be sure.
See this page for more info:
http://nathan.kopp.com/normals.htm
Somehow it seems this info did not get included in the POV 3.5 docs. See
section 6.7.2.4 of the docs for info about the no_bump_scale keyword, which
might help you get the desired result.
-Nathan
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