"StephenS" <nomail@nomail> wrote in message 
news:web.4a2171e71aa18c333d5bd1d30@news.povray.org...
> "JeffBTX" <nomail@nomail> wrote:
> ....
>
>> If someone can maybe explain the problem I am having posting ZIP 
>> attachments, > I
>> would appreciate it. I double checked. The original zip that I UPloaded 
>> DOES
>> extract with the DF3 file, but if I DOWNLOAD it out of the newsgroup, it 
>> is
>> empty. It is probably a Vista oddity.
>
> Did you use a news reader or the web interface?
> When the web interface was first set up, I had a problem downloading zip 
> files,
> I've not tried recently.
>
> Stephen S
>

Okay - I have figured out how to add the POVRay news server to Vista  -> 
Windows Mail (Outlook Express was left out of Vista). I am posting this now 
from my Vista -> WindowsMail newsreader, instead of the web interface as I 
have been doing.

For some reason, when I download my ZIP from Windows Mail (instead of the 
web interface), it extracts just fine (?)

Sorry, I have to experiment with attachments (zips) if I am to continue to 
contribute to the community... I have to waste bandwidth by testing with an 
attachment. I will attach that zipped DF3 again (under new filenames)... at 
least it is very small.

Post a reply to this message

Attachments:
Download 'df3file.zip' (1 KB)

"Alain" <ele### [at] netscapenet> wrote in message
news:4a21df34@news.povray.org...
> The documentations are WRONG about the default values used. They are:
> method 3
> intervals 1
> samples 3

Are you referring to section 3.6.2.2 (Sampling Parameters & Methods) in the
distribution documentation? If not a pointer please! This is one of the
things I'd like to start capturing and getting it into 3.7 doc repository on
the POV-Wiki!

Jim

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JeffBTX wrote:

> Sorry, I have to experiment with attachments (zips) if I am to continue 
> to contribute to the community... I have to waste bandwidth by testing 
> with an attachment.

note that there is a dedicated newsgroup povray.test

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Alain <ele### [at] netscapenet> wrote:
> There are NO artefacts when using version 3.7 beta 32 and interpolate 2.
> Interpolate 0 is NO interpolation. You only see the voxel.
> Interpolate 1 is linear interpolation. The voxel becomes fuzzy.
> With 3.6.1 and interpolate 2, there are HUGE artefacts. Making the container
> larger don't help, in fact, the result gets worst. Also, if you enlarge the
> container, you also need to increase the samples value a LOT. Adding 0.1 all
> around and you need samples 20, at least!

FYI:

The observed artifacts are due to the interpolation method; I encountered the
problem earlier, but from what I know it is not totally solved yet: I'd still
expect artifacts when doing the same "inverted", i.e. with a few isolated 0.0
values among a lot of 1.0 values.

Interpolation method 2 does something very similar to those splines that pass
right through the control points; if you place such a spline's control points
in straight line, but significantly displace a single one of them, the spline
will exhibit some distortion between the control points right next to the
"outsider"; there, the spline is displaced away from the "outsider".

A similar effect occurs with "interpolate 2": With all "control points" set to
0.0, but a single one set to 1.0, between the most adjacent points the values
will be interpolated as <0.0.

Similarly, if you set all values to 1.0, but set a single one to 0.0, the values
in the vicinity will be interpolated as >1.0.

This wouldn't have to be a problem - but in POV-Ray it is, because of the
automatic "wrap around" applied to patterns, with e.g. -0.1 being mapped to
+0.9, and +1.1 being mapped to +0.1.

Regular images are clipped to the interval [0.0, 1.0] between interpolation and
pattern wraparound; unfortunately, this is not the case for DF3 files: They are
clipped at the lower bound of 0.0, but the upper bound is still left unclipped,
and instead subject to pattern wraparound.

Note that it doesn't help to make a function from the DF3, because to the best
of my knowledge the only way to achieve this is a pattern function - which
obviously still involves a pattern, and the associated wraparound.

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JeffBTX nous illumina en ce 2009-05-31 04:40 -->
> First; I made an error, in the code to display the DF3, replace:
> //      emission 1*3
> //      absorption 1*5
> //      scattering {1, White*3 extinction 1}
> with:
> //      emission White*3
> //      absorption White*5
> //      scattering {1, White*3 extinction 1}
> 
> Okay...
> 
> StephenS;
> I am using the web interface to access the POV Ray newsgroup. In Vista, I am
> using "Windows Mail" (versus Outlook Express)... I've never tried to look at
> newsgroups with that before... I just tried... "Windows Mail" just downloads a
> list of microsoft.public.(xxx)(.xxx)(etc.) groups, no POVRay. Searched for
> help, in Vista Outlook Express no longer exists. I don't know what to do if I
> want to post .ZIPs for some reason... I am going to have to research adding
> different news servers to Vista Windows Mail (IF I can do that...). Any Vista
> users know a solution? Help? Inexperienced here, with this issue.
> 
> Tim;
> What you say makes perfect sense to me; that is, I understand it. But Alain says
> that doesn't really help... I posted the code from your post into a new POV
> file, tweaked the camera, etc., and rendered it. Using interpolate 2, the
> problem still exists.
> 
> Alain;
> Thanks for the information. POVRay 3.6.1c is the problem, then... I hate to
> download an ongoing work-in-progress beta though. I guess I just have to wait
> for an official 3.7 release... in the meantime, any work I do with DF3's will
> be suspect.
> 
> Oh, well.
> 
> - Thanks, all.
> 
> 
One thing you can do:
Try to avoid sharp drops to zero and very sharps drops to 1. Just add a border 
of 2's around 1's and 0's if you expect to use interpolate 2.

There is no problem with interpolate 1.
As there is no interpolation done with interpolate 0, you are also safe.

Post a reply to this message

Jim Holsenback nous illumina en ce 2009-05-31 08:34 -->
> "Alain" <ele### [at] netscapenet> wrote in message
> news:4a21df34@news.povray.org...
>> The documentations are WRONG about the default values used. They are:
>> method 3
>> intervals 1
>> samples 3
> 
> Are you referring to section 3.6.2.2 (Sampling Parameters & Methods) in the
> distribution documentation? If not a pointer please! This is one of the
> things I'd like to start capturing and getting it into 3.7 doc repository on
> the POV-Wiki!
> 
> Jim
> 
> 
Yes.
The documentation does say that method 3 is the default... in the text.
The stated defaults are still those of older versions when method 1 was the only 
sampling available.

Also, you need to read trough the text to find that the second samples parameter 
is not used with method 3, but the stated default values shown tend to imply 
that it is used.

In the tutorial, 2.3.6.6  A more advanced example of scattering media
The first tome that samples apears, it is: samples 30,100.
It should be: samples 30

In: 3.6.2  Media
We have this:
Media default values:

aa_level     : 4
aa_threshold : 0.1
absorption   : <0,0,0>
confidence   : 0.9
emission     : <0,0,0>
intervals    : 10
method       : 3
ratio        : 0.9
samples      : Min 1, Max 1
variance     : 1/128
SCATTERING
   COLOR        : <0,0,0>
   eccentricity : 0.0
   extinction   : 1.0

While the actual defaults are:
intervals 	: 1
samples		: 3 (NO min nor max, only a single value)
The other defaults seems to be correct and are concistent with the body of the text.

In section: 3.6.2.2  Sampling Parameters & Methods
It could be good to reorder the various methods to make method 3 the first one 
covered and mention that method 1 is a "legacy" method.

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"Alain" <ele### [at] netscapenet> wrote in message
news:4a25ce2a$1@news.povray.org...
> Yes.
> The documentation does say that method 3 is the default... in the text.
> The stated defaults are still those of older versions when method 1 was
the only
> sampling available.
>
> Also, you need to read trough the text to find that the second samples
parameter
> is not used with method 3, but the stated default values shown tend to
imply
> that it is used.
>
> In the tutorial, 2.3.6.6  A more advanced example of scattering media
> The first tome that samples apears, it is: samples 30,100.
> It should be: samples 30
>
> In: 3.6.2  Media
> We have this:
> Media default values:
>
> aa_level     : 4
> aa_threshold : 0.1
> absorption   : <0,0,0>
> confidence   : 0.9
> emission     : <0,0,0>
> intervals    : 10
> method       : 3
> ratio        : 0.9
> samples      : Min 1, Max 1
> variance     : 1/128
> SCATTERING
>    COLOR        : <0,0,0>
>    eccentricity : 0.0
>    extinction   : 1.0
>
> While the actual defaults are:
> intervals : 1
> samples : 3 (NO min nor max, only a single value)
> The other defaults seems to be correct and are concistent with the body of
the text.
>
> In section: 3.6.2.2  Sampling Parameters & Methods
> It could be good to reorder the various methods to make method 3 the first
one
> covered and mention that method 1 is a "legacy" method.

Merci Alain .... Good stuff I will follow up! Jim

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.... just thought I would post another example.

It's interesting looking.

Reminds me of "The Andromeda Strain".

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Attachments:
Download 'df3_test.jpg' (31 KB)

Preview of image 'df3_test.jpg'

"Alain" <ele### [at] netscapenet> wrote in message
news:4a21df34@news.povray.org...
> The documentations are WRONG about the default values used.

Alain,

Please have a look at:
http://wiki.povray.org/content/Documentation_Talk:Reference_Section_6.1

I settled for adding a "Note" explaining the default changes. If you are
registered user on the Wiki please feel free to offer any changes there if I
didn't get it exactly right. Response to this thread works for me as well.

Jim

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