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Nieminen Mika <war### [at] cc tutfi> writes:
> Targa supports also compression. Can you specify which kind of
> compression?
Run length encoding (RLE). One group of consecutive pixels of the
exact same colour is coded on two (resp. three or four) bytes as a
whole instead of one (resp. two or three) byte for each pixel. This
allows to use only two bytes to code one hundred pixels if they have
the exact same colour (assuming we are in an eight bits per pixel
image). Of course, if you have horizontal gradients, this increases
the size of the file instead of diminishing it, but it generally
behaves The Right Way.
Roland.
--
Roland Mas
- Genki desu, ture en zinc.
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Ron Parker wrote in message <36e9234a.0@news.povray.org>...
>On Fri, 12 Mar 1999 08:43:46 -0500, Greg M. Johnson <@aol.com> wrote:
>>Suggestions for additional topics include:
>>
>>1. Why raytracers cannot do caustics :
>>2. Why raytracers cannot make a "homemade" spotlight:
>
>These are, of course, both the same topic. Clearly one would need
>to start with a definition of caustics.
Which is covered in the VFAQ I would guess, and:
Not entirely true anyway, as Nathan is showing us with his new patched
version of POV-Ray.
The statement "cannot do caustics" should be "usually, and with the current
technique - if they are not enhanced with photon-maps or something similar -
cannot do caustics" ;-)
Johannes.
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Nieminen Mika wrote:
>
> I started another page with the same idea of the VFAQ page: The
> common misunderstandings page. The intention of the page is to clear up
> some common misunderstanings people have about computer related things
> (mainly about topics related with povray, graphics, etc). The page has
> only one entry right now, which is a very good example of what I mean.
> Wrong allegations and correct information about them is very welcome.
> I'll add a link to the page from the VFAQ page if/when I get some more
> entries.
Mis-whatevers:
Q.) Why don't they implement a modeling interface into Pov-Ray
A.) Pov-Ray is a rendering engine. This means it is designed to read a
text based scene discription language and output an image for it.
The programming work to keep this working bug free and adding
features at regular intervals takes a lot time and energy by the all
volunteer programming team. Adding a modeling interface would add to
their aleady heavy workload and the progam was never written to be a
modeling program anyway. There are numerous modeling programs already
available that are designed with the sole purpose of providing a
graphical modeling interface to Pov so it really isn't neccessary for
the programming team to think about adding one.
And... or...
Q.) Why can't I use 3ds, dxf, vrml, or whatever models directly without
having to convert them to triangles first ?
A.) ?
For Ron Parker:
Q.) If I just add the inverse keyword to my triangle meshes shouldn't they
work in csg operations ?
A.) ?
--
Ken Tyler
mailto://tylereng@pacbell.net
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On Fri, 12 Mar 1999 08:42:38 -0800, Ken <tyl### [at] pacbellnet> wrote:
>For Ron Parker:
>
>Q.) If I just add the inverse keyword to my triangle meshes shouldn't they
> work in csg operations ?
>
>A.) ?
Wow. Drifting across newsgroup boundaries now. I'm impressed.
A.) No. There is no way to find the "inside" of an arbitrary triangle
mesh, so the current implementation just assumes that nothing is inside of
a mesh object. Adding the inverse keyword would just change it to say
that everything is inside of a mesh object. The result would be that
intersecting an inverted mesh with a sphere would leave the entire sphere,
plus whatever part of the mesh is inside the sphere. The correct result,
of course, would be to leave only the parts of the sphere that are "outside
the mesh," and only the parts of the mesh that are inside the sphere. The
problem comes in when POV tries to define "outside the mesh."
The real common misunderstanding here, and one I've been guilty of, is
"If I want to make an object work in CSG, all I have to do is add an
insideness test, right?" The answer is no: you also have to ensure that
the all_intersections routine for your object really does return all of
the intersections for any given ray. The other common misconception is
that an insideness test for meshes is as simple as counting intersections.
See the recent and ongoing discussion in povray.programming for more than
you ever wanted to know about these topics.
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Stephen Lavedas wrote:
> My personal biggest pet peeve, which isn't about POVRay or Graphics is
> when people ask..."Are you on the Internet" and they mean World Wide
> Web. The Internet is so much bigger than just the Web that I want to
> smack them one and point out what else is out there.
>
> Steve
As immortalized by Bob Dole (American presidential candidate from a few years
ago, failed, for you who are lucky enough not to live with American politics) :
"The Internet is the fastest way to get on the Web."
--
Josh English
eng### [at] spiritonecom
www.spiritone.com/~english
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Nieminen Mika wrote:
>
> I started another page with the same idea of the VFAQ page: The
> common misunderstandings page. The intention of the page is to clear up
> some common misunderstanings people have about computer related things
> (mainly about topics related with povray, graphics, etc). The page has
> only one entry right now, which is a very good example of what I mean.
> Wrong allegations and correct information about them is very welcome.
> I'll add a link to the page from the VFAQ page if/when I get some more
> entries.
> The page can be found at:
>
> http://iki.fi/warp/misunderstandings/
>
> --
> main(i,_){for(_?main(i+1,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[--i]
> ):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
I remember one in c.g.r.r. about the stacks in POVray and the
misunderstanding that they can be increased in autoexec.bat (or
config.sys ?). Somebody wiser than me should give the answer. If I
remember right it's not in the VFAQ.
Marc
--
Marc Schimmler
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Anthony Bennett wrote:
>
> > So which formats are better than the other?
> > If you had to use a scale of 1 - 10 ...is png better than jpeg, gif
> > etc.
> > I assume the bitmap is the best, or maybe not...you tell me.
Hmm, a question here, the Huffman compression technique that is used in many of
the newer compression algorithms(RAR, ARJ and so on) is used in the zip format
as well, If I'm not misunderstanding what I read. But, as far as I know, the PNG
uses a dynamic compression table, in difference to the standard zip algorithm
that uses a static table. am I correct or totally lost in my compression?
Another file format I'd like some tips on is the FIF(Fractal Image Format)
I had a compressor/viewer for this once, but lost it as so many otehr progs.
Anyone has anything on where I can find a program that can store to this? It was
very good at shrinking files, admittedly with loss, but the technique used made
it possible to zoom into the image in a totally different way than any
rasterized(bitmapped) format allows.
--
//Spider
( spi### [at] bahnhofse ) [ http://www.bahnhof.se/~spider/ ]
#declare life = rand(seed(42))*sqrt(-1);
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Spider wrote:
> Another file format I'd like some tips on is the FIF(Fractal Image Format)
> I had a compressor/viewer for this once, but lost it as so many otehr progs.
> Anyone has anything on where I can find a program that can store to this? It was
> very good at shrinking files, admittedly with loss, but the technique used made
> it possible to zoom into the image in a totally different way than any
> rasterized(bitmapped) format allows.
>
> --
> //Spider
> ( spi### [at] bahnhofse ) [ http://www.bahnhof.se/~spider/ ]
> #declare life = rand(seed(42))*sqrt(-1);
Take a look in announce.frequently-asked-questions for a list of
links that will take you to faq's on image file format formats and
related image resources on the net. It's the best starting place I
know to send you for the info you seek.
--
Ken Tyler
mailto://tylereng@pacbell.net
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I've been looking into this issue this week.
PNG and JPG are complementary, not competitors.
Use PNG for lossless work-in-progress and still get some compression.
Use JPEG for final pieces.
Phil Clute wrote in message <36E81BB3.1250B1D2@tiac.net>...
So which formats are better than the other?
If you had to use a scale of 1 - 10 ...is png better than jpeg, gif
etc.
I assume the bitmap is the best, or maybe not...you tell me.
--
...coffee?...yes please! extra sugar,extra cream...Thank you.
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Attachments:
Download 'iso-8859-1' (2 KB)
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Thanx. I'll do that sometime when I feel bored :-) This prog. isn't really on
top of my list of TOGET things
--
//Spider
( spi### [at] bahnhofse ) [ http://www.bahnhof.se/~spider/ ]
#declare life = rand(seed(42))*sqrt(-1);
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