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Strange...
I always thought that POV-ray's rendered images were always
exactly the same for the same code, like with 'normal'(?)
instructions.
Example: if you calculate tan 1 with a calculator, you
always
get the same result: 1.55740772465490223050697480745836(...)
However, it appears this doesn't work this way for POV-ray
image output (?).
I've rendered the same POV code more than once on the same
computer without using any jittering or crand or any other
random
function that I know of. The results were slightly
different, as
you can see in the attached image (that's why I posted it in
this group)
(close-ups of the rendered images).
Can anybody tell me why the output is different?
Just wondering...
Julius
Post a reply to this message
Attachments:
Download 'renders.jpg' (6 KB)
Preview of image 'renders.jpg'
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Julius Klatte wrote:
> (close-ups of the rendered images).
> Can anybody tell me why the output is different?
> Just wondering...
> Julius
Maybe it's gremlins.
What do you want for free ?
Have you checked for viruses lately ?
Did someone turn on a blender or something while the image was rendering ?
Seriously I haven't a clue. Sorry.
--
Ken Tyler
mailto://tylereng@pacbell.net
Post a reply to this message
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Did you use any #macros or looping runs (#if #while, etc.) ?
KB-
Julius Klatte wrote:
> Strange...
> I always thought that POV-ray's rendered images were always
> exactly the same for the same code, like with 'normal'(?)
> instructions.
>
> Example: if you calculate tan 1 with a calculator, you
> always
> get the same result: 1.55740772465490223050697480745836(...)
>
> However, it appears this doesn't work this way for POV-ray
> image output (?).
> I've rendered the same POV code more than once on the same
> computer without using any jittering or crand or any other
> random
> function that I know of. The results were slightly
> different, as
> you can see in the attached image (that's why I posted it in
> this group)
> (close-ups of the rendered images).
> Can anybody tell me why the output is different?
>
> Just wondering...
>
> Julius
>
> [Image]
Post a reply to this message
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Is there any possibility that anti-aliasing uses a rand function? Did you
render this with AA on or off?
Julius Klatte <jku### [at] hotmail com> wrote in message
news:370e8cb3.0@news.povray.org...
> Strange...
> I always thought that POV-ray's rendered images were always
> exactly the same for the same code, like with 'normal'(?)
> instructions.
>
> Example: if you calculate tan 1 with a calculator, you
> always
> get the same result: 1.55740772465490223050697480745836(...)
>
> However, it appears this doesn't work this way for POV-ray
> image output (?).
> I've rendered the same POV code more than once on the same
> computer without using any jittering or crand or any other
> random
> function that I know of. The results were slightly
> different, as
> you can see in the attached image (that's why I posted it in
> this group)
> (close-ups of the rendered images).
> Can anybody tell me why the output is different?
>
> Just wondering...
>
> Julius
>
>
>
Post a reply to this message
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In answer to your (pretty quick!) reactions:
>Did you use any #macros or looping runs (#if #while,
etc.) ?
No. But that shouldn't influence the render result either...
>Maybe it's gremlins.
Hmmm... there's an interesting suggestion...
>What do you want for free ?
I'm not complaining!
>Have you checked for viruses lately?
Yes. I spoke to some of them yesterday. But they didn't tell
me: "Hey, we're not going to mess up your system, just the
tiny details of your POV images." Not that you can trust 'em
of course.
>Did someone turn on a blender or something while the image
was rendering ?
Well, the neighbours were having a fight...
>Seriously I haven't a clue. Sorry.
You're disappointing me... :)
>Is there any possibility that anti-aliasing uses a rand
function? Did you
>render this with AA on or off?
That was my first guess as well. I'm not sure if
anti-aliasing is random. I always thought it was a standard
per-pixel routine.
The image(s) I attached were with anti-aliasing, but I tried
another time with AA off and that sure made things
blockier..., but still there were slight variations in the
images.
I'm not really having any problem with the phenomenon, since
the effect is invisible for unzoomed rendered images, but it
just struck me as strange...
Thanks anyway
Julius
Post a reply to this message
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I don't have an answer either, but from the looks of this image, which
looks to be enlarged to almost the nonoscopic level:-) you could hardly
notice these variances.
Julius Klatte wrote:
> Strange...
> I always thought that POV-ray's rendered images were always
> exactly the same for the same code, like with 'normal'(?)
> instructions.
>
> Example: if you calculate tan 1 with a calculator, you
> always
> get the same result: 1.55740772465490223050697480745836(...)
>
> However, it appears this doesn't work this way for POV-ray
> image output (?).
> I've rendered the same POV code more than once on the same
> computer without using any jittering or crand or any other
> random
> function that I know of. The results were slightly
> different, as
> you can see in the attached image (that's why I posted it in
> this group)
> (close-ups of the rendered images).
> Can anybody tell me why the output is different?
>
> Just wondering...
>
> Julius
>
> [Image]
Post a reply to this message
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It is most definitely the AA. That is random in it's treatment of
pixels. You've really got me there on how it looks different even with
AA off. The only logical explanation is the gremlins, as Mr. Tyler
suggested.
Post a reply to this message
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Try the same code numerous times on another computer.
GrimDude
vos### [at] arkansasnet
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'jitter' as you all might know is random on a frame by frame basis, not
to be used when making animation frames you know.
If no AA there is no jitter as I understood it, but makes me wonder now.
It has the ability to be on, off, off with a number which will be used
on the next render, etc. so maybe the answer lies there.
Julius Klatte wrote:
>
> In answer to your (pretty quick!) reactions:
>
> >Did you use any #macros or looping runs (#if #while,
> etc.) ?
> No. But that shouldn't influence the render result either...
>
> >Maybe it's gremlins.
> Hmmm... there's an interesting suggestion...
> >What do you want for free ?
> I'm not complaining!
> >Have you checked for viruses lately?
> Yes. I spoke to some of them yesterday. But they didn't tell
> me: "Hey, we're not going to mess up your system, just the
> tiny details of your POV images." Not that you can trust 'em
> of course.
> >Did someone turn on a blender or something while the image
> was rendering ?
> Well, the neighbours were having a fight...
> >Seriously I haven't a clue. Sorry.
> You're disappointing me... :)
>
> >Is there any possibility that anti-aliasing uses a rand
> function? Did you
> >render this with AA on or off?
> That was my first guess as well. I'm not sure if
> anti-aliasing is random. I always thought it was a standard
> per-pixel routine.
> The image(s) I attached were with anti-aliasing, but I tried
> another time with AA off and that sure made things
> blockier..., but still there were slight variations in the
> images.
>
> I'm not really having any problem with the phenomenon, since
> the effect is invisible for unzoomed rendered images, but it
> just struck me as strange...
>
> Thanks anyway
>
> Julius
--
omniVERSE: beyond the universe
http://members.aol.com/inversez/homepage.htm
mailto:inv### [at] aolcom?Subject=PoV-News
Post a reply to this message
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This phenomenon appears to me to be cyclical, suggesting that it
may be memory getting full, and clearing out and starting again,
something like that.
We know nothing about the size of the whole image, the object
count, are you using atmosphere, I'm sure that has some random
factor, media too.
I'd be tempted to look at the code.
Steve
Julius Klatte wrote:
>
> Strange...
> I always thought that POV-ray's rendered images were always
> exactly the same for the same code, like with 'normal'(?)
> instructions.
>
> Example: if you calculate tan 1 with a calculator, you
> always
> get the same result: 1.55740772465490223050697480745836(...)
>
> However, it appears this doesn't work this way for POV-ray
> image output (?).
> I've rendered the same POV code more than once on the same
> computer without using any jittering or crand or any other
> random
> function that I know of. The results were slightly
> different, as
> you can see in the attached image (that's why I posted it in
> this group)
> (close-ups of the rendered images).
> Can anybody tell me why the output is different?
>
> Just wondering...
>
> Julius
>
> [Image]
Post a reply to this message
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