Yesterday I sent an animation to p.b.a. I agree that the size of the
file was very large for what the animation represents. I think this has
to do with the method I use for preparing the animated giffile. The few
animations I sent earlier fortunately where much smaller.
Using the animation possibilities of Povray I obtain a number of png
files. Those png files are converted to giffiles using Irfanview. Using
Movgear an animated giffile is constructed. Such an animated giffile can
be optimized and in most cases the gain is very extensive.
But yesterday this wasn't the case. I pointed out that this has to do
with the use of AA 0.3. and the conversion from png to giffiles. Parts
of two successive images that have a large part in common aren't
transformed in the same way. This results in a flickering in the
animated giffile and of course the gain obtained by optimizing is very
small, because there are to many differences between two following
images.
Is there a possibility to avoid these kinds of problems? I'm using
Windows 98.
Thanks.
-- 
Herman Serras
Gent (Belgium)
http://cage.rug.ac.be/~hs/

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"Herman Serras"  wrote:
> Is there a possibility to avoid these kinds of problems?

Yes, use another codec.

Simon

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Simon Adameit wrote:

> "Herman Serras"  wrote:
> 
>>Is there a possibility to avoid these kinds of problems?
>>
> 
> Yes, use another codec.
 
Better, use mpeg-1 encoders (and no fancy codec).

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> Better, use mpeg-1 encoders (and no fancy codec).
At which point is a codec fancy?

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Sebastian H.
> > Better, use mpeg-1 encoders (and no fancy codec).
> At which point is a codec fancy?

When it's something else than mpeg-1? :)


--
-Jide

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Sebastian H. wrote:

>> Better, use mpeg-1 encoders (and no fancy codec).
> 
> At which point is a codec fancy?


Whenever it is not available with the basic installation of
the MS player (so, probably only "Full Uncompressed Frame" is ok,
because even Intel Indeo codec have too many incompatible versions).

The bad codec are the one you get because you installed some additional
software. The worst are the one which came with hardware. (but they
usually compress better (??)).
Just think about someone which has not the same computer...


Last point, Automatic research of missing codec usually fails.

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> 
> When it's something else than mpeg-1? :)
> 
That leaves little scope :-)

Sebastian H.

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The codec has importance for sure. But your images suffer from bad anti
aliasing. This is not a matter of AA 0.3 (the threshold) but a matter of
jittering. Jittering is noise and that's bad in animations. A good
anti-alias gives a fully similar result for every frame, thus allowing the
video compressor to forget the parts of the image that doesn't change.

I understand that you tried this, but couldn't turn off jittering.. I've
been thinking about why.. Maybe it's because I forgot that you're probably
using an ".ini" file to setup the animation.. In that case, you can change
the anti-alias settings in the ".ini" file. You could try this:

Jitter_Amount=0

It won't change the quality of anti-aliasing, but should remove the noise in
your sequence, and this would give a huge improvement in file size.

I also mentioned using grey-scales instead of strong contrasts in color..
Well, these are two 'extreme' choices.. I know greyscales would be kind of
boring, but from a technical point of view, they compress better (with jpeg
/ mpeg).. So, a good choice is usually something 'in between'.. That means
not greyscale, and not strong color contrasts.. Of course you could force
the filesize to be similar for both types of image, but the picture quality
will differ.

Good luck, and let me know if I'm not clear.  ;o)

Regards,
Hugo

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Hugo wrote:
> 
> The codec has importance for sure. But your images suffer from bad anti
> aliasing. This is not a matter of AA 0.3 (the threshold) but a matter of
> jittering. Jittering is noise and that's bad in animations. A good
> anti-alias gives a fully similar result for every frame, thus allowing the
> video compressor to forget the parts of the image that doesn't change.
> 
> I understand that you tried this, but couldn't turn off jittering.. I've
> been thinking about why.. Maybe it's because I forgot that you're probably
> using an ".ini" file to setup the animation.. In that case, you can change
> the anti-alias settings in the ".ini" file. You could try this:
> 
> Jitter_Amount=0
> 
> It won't change the quality of anti-aliasing, but should remove the noise in
> your sequence, and this would give a huge improvement in file size.
> 
> I also mentioned using grey-scales instead of strong contrasts in color..
> Well, these are two 'extreme' choices.. I know greyscales would be kind of
> boring, but from a technical point of view, they compress better (with jpeg
> / mpeg).. So, a good choice is usually something 'in between'.. That means
> not greyscale, and not strong color contrasts.. Of course you could force
> the filesize to be similar for both types of image, but the picture quality
> will differ.
> 
> Good luck, and let me know if I'm not clear.  ;o)
> 
> Regards,
> Hugo

Putting Jitter_Amount=0 in the ini file already helped a lot in reducing
the size of the animated gif file and the flickering in the animation
disappeared, but playing around with different values for
Antialias_Treshold and Antialias_Depth I noticed that still more
benefits were got from putting the antialias_depth to 1.
In the orininal posting I explained how I get the animated giffile. I
wonder if there's another way to obtain small animation files starting
with a number of png files obtained using the animation possibilities of
Povray. I'm working with Windows 98.

Friendly greetings and thanks for the help!

-- 
Herman Serras
Gent (Belgium)
http://cage.rug.ac.be/~hs/

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