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"WaveMaster" <nos### [at] yahoo com> wrote:
Here you can download the animation of the preceding example (about 4.7
MByte).
It is a short .AVI file, encoded with Windows Media Encoder v9.
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_01_0505_0550.avi
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Here comes an updated, longer version of the preceding animation scene
(6.2 MByte) This animation was rendered with MegaPov 1.21:
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_01_MegaP_0500_0560.avi
The next link shows the same scene but exactly 90 degrees later. You can see
the opposite effect as soon as the camera leaves the fractal shape (6.3
MByte):
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_01_MegaP_1440_1499.avi
You can also rotate the fractal around the x-axis instead of the y-axis. As
soon as the camera comes near the fractal shape, the inner flow makes an
extream acceleration change.
How can I avoid this or is this an error???
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"WaveMaster" <nos### [at] yahoocom> wrote:
> Here comes an updated, longer version of the preceding animation scene
> (6.2 MByte) This animation was rendered with MegaPov 1.21:
>
>
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_01_MegaP_0500_0560.avi
>
>
> The next link shows the same scene but exactly 90 degrees later. You can see
> the opposite effect as soon as the camera leaves the fractal shape (6.3
> MByte):
>
>
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_01_MegaP_1440_1499.avi
>
>
> You can also rotate the fractal around the x-axis instead of the y-axis. As
> soon as the camera comes near the fractal shape, the inner flow makes an
> extream acceleration change.
>
>
> How can I avoid this or is this an error???
I think it's still the wheel effect. If you make a wheel animation and let
its velocity vary, you'll see it alterning between clockwise and
counter-clockwise rotation, even though it's "really" only going in one
direction in the code. Likewise, in your scene, angular velocity varies a
lot when you try to go in the fractal, as opposed to the fairly smooth
movement in the beginning of the animation.
That's my guess, anyway.
You may find you'd get more feedback if you used non-Windows specific
codecs, Xvid or Mpeg should be supported on a fair number of platforms.
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> You may find you'd get more feedback if you used non-Windows specific
> codecs, Xvid or Mpeg should be supported on a fair number of platforms.
As wished here comes the MPEG2 version of the preceding downloadlinks:
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_01_MegaP_0500_0560.mpg
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_01_MegaP_1440_1499.mpg
both files are about 2.3 MByte
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I did a new rendering with a new scene-file. The following changes have been
made:
camera{
location <0, 0,-650> // position of camera <X Y Z>
sky y
up <0, 1, 0> // which way is +up <X Y Z>
right <-1.77 0.0 0.0> // which way is +right <X Y Z> and aspect ratio
look_at <0.0, 0, 0> // point center of view at this point <X Y Z>
}
light_source{
<0, 0,-380>
color rgb 1.8
}
julia_fractal{
<-0.5664, 0.5106, 0.0224, -0.3024>
slice <0,0.43,0,1.0>, 0.0
precision 50
max_iteration 38
quaternion
sqr
hollow on
texture {
pigment{
rgb <1,1.0,1.0> // White
}
finish {
ambient 0.09
metallic 0.4
}
}
rotate <-2,19,0>
rotate <0,0,-10>
scale <250, 250, 1000>
rotate<0,90+clock*360*1,0>
translate <0, 135, 0>
}
julia_fractal{
<-0.5664, 0.5106, 0.0224, -0.3024>
slice <0,0.43,0,1.0>, 0.0
precision 50
max_iteration 38
quaternion
sqr
hollow on
texture {
pigment{
rgb <0.5,1.0,0.5> // Green
}
finish {
ambient 0.09
metallic 0.4
}
}
rotate <-2,19,0>
rotate <0,0,-10>
scale <250, 250, 900>
rotate<0,90+clock*360*1,0>
translate <0, -135, 0>
}
Download link:
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_04_MegaP_0530_0599.m2v
Afterwards I rendered the following scene-file:
julia_fractal{
<-0.5664, 0.5106, 0.0224, -0.3024>
slice <0,0.43,0,1.0>, 0.0
precision 50
max_iteration 38
quaternion
sqr
hollow on
texture {
pigment{
rgb <1,1.0,1.0> // White
}
finish {
ambient 0.09
metallic 0.4
}
}
rotate <-2,19,0>
rotate <0,0,-10>
scale <250, 250, 1000>
rotate<0,90+clock*360*1,0>
translate <0, -135, 0>
}
julia_fractal{
<-0.5664, 0.5106, 0.0224, -0.3024>
slice <0,0.43,0,1.0>, 0.0
precision 50
max_iteration 38
quaternion
sqr
hollow on
texture {
pigment{
rgb <0.5,1.0,0.5> // Green
}
finish {
ambient 0.09
metallic 0.4
}
}
rotate <-2,19,0>
rotate <0,0,-10>
scale <250, 250, 900>
rotate<0,90+clock*360*1,0>
translate <0, 135, 0>
}
Download Link:
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_04b_MegaP_0530_0599.m2v
Facts:
The white fractal has a z-scale by 1000, the new green fractal has a z-scale
by 900. The rest stays identical. Both fractals have a symmetrical
y-translation by +/-135 units.
If the inner move is made by the "wheel effect", then both fractals should
change the inner move on different positions/in different directions. But
as you can see, the inner move changes at the same position in both
fractals.
The second example exchanges only the two fractals in the y-direction. And
again, both fractals change the inner move at the same position!!
Question:
Can this facts be explained by the wheel effect??
For me, there is an error in the fractal calculation!!
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"WaveMaster" <nos### [at] yahoocom> wrote:
> Facts:
>
> The white fractal has a z-scale by 1000, the new green fractal has a z-scale
> by 900. The rest stays identical. Both fractals have a symmetrical
> y-translation by +/-135 units.
>
> If the inner move is made by the "wheel effect", then both fractals should
> change the inner move on different positions/in different directions. But
> as you can see, the inner move changes at the same position in both
> fractals.
>
> The second example exchanges only the two fractals in the y-direction. And
> again, both fractals change the inner move at the same position!!
>
> Question:
>
> Can this facts be explained by the wheel effect??
> For me, there is an error in the fractal calculation!!
I'm not sure it proves anything, actually. Could there be a bug in how
POV-ray handles Julias? Certainly! It wouldn't be the first time. You are
saying that two wheels, one smaller and one bigger but with spokes at the
same relative angles, wouldn't display the same "wheel effect" as their
rotation speed increased. But the wheel effect is determined by the angular
velocity of the rotation: in your scene that is determined solely by the
rotation of the clock, as angular velocity is independent of radius.
Consequently both scenes display the same behaviour.
I believe that in order to overcome the problem you need to have smaller
steps the closer you get to the fractal. Unfortunately there is no "fixed
step" rotation that can avoid the effect, AFAIK.
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The final prove that there are errors in the fractal calculation:
-----------------------------------------------------------------
First the Source Code:
global_settings {number_of_waves 10}
global_settings {assumed_gamma 1.0}
global_settings {max_trace_level 10}
global_settings {adc_bailout 0.006}
global_settings {
photons {
count 40000
media 100
gather 30, 120
autostop 0
jitter .4
}
}
camera{
location <0, 0,-455+150.0*clock>
sky y
up <0, 1, 0>
right <-1.77 0.0 0.0>
look_at <0.0, 0, 0>
}
light_source{
<0, 0,-380>
color rgb 1.6
}
julia_fractal {
<-0.4, 0.4, -0.4, 0.4>
quaternion
sqr
slice <0,0,0.0,1.0>, 0.0
precision 14
max_iteration 24
texture {
pigment{
checker
pigment{
rgb <1,1.0,1.0>
},
pigment{
rgb <1,1.0,0.3>
}
scale <0.05,0.05,0.05>
}
finish {
ambient 0.09
metallic 0.4
}
}
hollow on
rotate <-2,19,0>
rotate <0,0,-10>
scale <260, 210, 1000>
rotate <0, 96, 0>
translate <0.0, -8, 0>
}
The fractal has no rotation. Only a simple translation from outside into the
fractal. As soon as you come near the shape of the fractal, you have a
calculation change of the fractal. In the animation, you can see two
different ellipses which grow. Inside the ellipses you can see, that some
parts of the fractal are on another position as they were at the begining
(Outside the shape). The amount of ellipses varies on the angel you hit the
shape. When the fractal slowly rotates around the y-axis you can see up to 6
different ellipses they start from a point and grows over the whole
fractal-image.
Animation Link:
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_08_MegaP_001_200.m2v
Can anyone explain this kind of animation effect?
Is that also a Wheel effect??
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"WaveMaster" <nos### [at] yahoocom> wrote:
> The final prove that there are errors in the fractal calculation:
> -----------------------------------------------------------------
>
> First the Source Code:
>
> [...]
>
> The fractal has no rotation. Only a simple translation from outside into the
> fractal. As soon as you come near the shape of the fractal, you have a
> calculation change of the fractal. In the animation, you can see two
> different ellipses which grow. Inside the ellipses you can see, that some
> parts of the fractal are on another position as they were at the begining
> (Outside the shape). The amount of ellipses varies on the angel you hit the
> shape. When the fractal slowly rotates around the y-axis you can see up to 6
> different ellipses they start from a point and grows over the whole
> fractal-image.
>
> Animation Link:
>
>
http://homepage.sunrise.ch/mysunrise/go_huerlimann/PovRay/FractalTest_08_MegaP_001_200.m2v
>
> Can anyone explain this kind of animation effect?
> Is that also a Wheel effect??
Of course it isn't the wheel effect here. I do not know how POV makes the
calculations so I can only guess at the cause, but that looks like an error
in calculations that gets propagated. Try using the "sturm" keyword to
obtain more accurate roots. If the error persists even using sturm, then it
is likely a bug in the code.
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I have tried to render the fractal-object with the following statement
inside:
sturm true
I couldn't render the animation, because the current versions of Povray and
also MegaPov don't support this feature.
Is there another possibility to switch on the new root solver mode for a
fractal object???
Important Data to know:
Current Povray-Version : 3.6.1c.icl8.win32
Current MegaPov-Version: 1.2.1/based on 3.6.1.msvc7 unofficial-win32
Operating system: Windows XP pro with sp2
Processor: Pentium 4 2.4 GHz.
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"WaveMaster" <nos### [at] yahoocom> wrote:
> I have tried to render the fractal-object with the following statement
> inside:
>
> sturm true
>
> I couldn't render the animation, because the current versions of Povray and
> also MegaPov don't support this feature.
>
> Is there another possibility to switch on the new root solver mode for a
> fractal object???
>
> Important Data to know:
>
> Current Povray-Version : 3.6.1c.icl8.win32
> Current MegaPov-Version: 1.2.1/based on 3.6.1.msvc7 unofficial-win32
> Operating system: Windows XP pro with sp2
> Processor: Pentium 4 2.4 GHz.
It doesn't work? Oops, I'm dreadfully sorry. Taking a look at the manual it
seems that you can crank up precision and/or max_iteration. It looks like
Julia fractals aren't that well implemented in POV-ray yet.
Before I even heard of Pov, I was quite smitten with a program called
Chaoscope. Animation support has been recently added to it, making it a
very interesting tool for exploring strange attractors. You can always
reimport the Chaoscope images into POV-ray as heightfields for fancy
renders. Chaoscope also supports several other non Julia attractors. You
can find it at http://www.btinternet.com/~ndesprez/
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