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POV-Ray doesn't support mipmaps. What you normally do to avoid aliasing is
use (*tadaa*) antialiasing.
There are two methods in POV-Ray, I tend to use the adaptive one to make use
of higher but more controlled sampling. Aside of that, there'll sure be a
way to script your own kind of mipmapping (switching the texture dependant
on distance to the camera, for example), but I don't have a script "off the
shelf" for that.
That aside, once you switch on arealights, radiosity, reflections,
refractions and media, I doubt that your realtime images look better (or
that they're even realtime then). ;-P
Regards,
Tim
--
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
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> POV-Ray doesn't support mipmaps. What you normally do to avoid aliasin
g
> is
> use (*tadaa*) antialiasing.
>
> There are two methods in POV-Ray, I tend to use the adaptive one to ma
ke
> use
> of higher but more controlled sampling. Aside of that, there'll sure b
e a
> way to script your own kind of mipmapping (switching the texture
> dependant
> on distance to the camera, for example), but I don't have a script "of
f
> the
> shelf" for that.
>
> That aside, once you switch on arealights, radiosity, reflections,
> refractions and media, I doubt that your realtime images look better (
or
> that they're even realtime then). ;-P
You are right, of course :)
I described my current state, when i tried to export my realtime scenes
into
povray without doing fancy things you mentioned.
What is the other antialising method? If you could post some settings
i can play with it would be great.
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tahoma wrote:
> When using image_maps i could not manage to get really nice visual
> results because of high sampling frequencies.
> Is there a way to specify mipmaps in povray or can povray do it by
> itself? The only interpolation schemes i found are 'bilinear' and
> 'normalized distance'.
Sorry but the fact you write this shows that you have absolutely no idea
how raytracing works and what mip-mapping is.
I don't want to appear brusk but you should think about things and
inform yourself a bit better before posting something like this.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 03 May. 2005 _____./\/^>_*_<^\/\.______
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>> When using image_maps i could not manage to get really nice visual
>> results because of high sampling frequencies.
>> Is there a way to specify mipmaps in povray or can povray do it by
>> itself? The only interpolation schemes i found are 'bilinear' and
>> 'normalized distance'.
>
> Sorry but the fact you write this shows that you have absolutely no id
ea
> how raytracing works and what mip-mapping is.
Exactly what does imply your opinion? Because i did ask for a feature
that seems to be nonsense in you eyes?
> I don't want to appear brusk but you should think about things and
> inform yourself a bit better before posting something like this.
You do not appear brusk. I know that i just started to understand
raytracing (especially povray). That is a long way.
I read documentations and so on. Nevertheless it is
useful to share one's thoughts with others even when they appear to be
dumb. Thats how learning works in my opinion. If you dont want to answer
to my questions, no problem. I know i am an 'alien' at this place, but
to discourage me is maybe the wrong way.
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tahoma <tah### [at] gmx de> wrote:
> Is there a way to specify mipmaps in povray or can povray do it by itself?
You probably don't want mipmapping alone, because all by itself it's
pretty useless (well, not useless, but it causes a very visible abrupt
change at the places where the mipmap level changes). What you want
is trilinear interpolation.
Unfortunately POV-Ray does not support that. There are a couple of
problems implementing trilinear interpolation in a raytracer. They can
probably be solved, but it's not as trivial as in a scanline renderer.
--
- Warp
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Tim Nikias <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:
> POV-Ray doesn't support mipmaps. What you normally do to avoid aliasing is
> use (*tadaa*) antialiasing.
Antialiasing doesn't help too much when there are dozens of imagemap
pixels in one result image pixel. It helps a bit, but does not give
such a good result as trilinear interpolation.
--
- Warp
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Christoph Hormann <chr### [at] gmxde> wrote:
> Sorry but the fact you write this shows that you have absolutely no idea
> how raytracing works and what mip-mapping is.
How so?
I don't see why mipmapping, and better yet trilinear interpolation
of image maps could not be implemented in a raytracer. There are a
couple of twists, but they can be probably solved.
--
- Warp
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> What is the other antialising method? If you could post some
> settings i can play with it would be great.
Both settings can be set via the commandline. If you're using POV-Ray for
Windows, there's a small box on the top where you can enter options. To
switch antialiasing on, add "+AM1" or "+AM2" (without the quotation marks)
into the box. That'll select antialiasing method 1 or 2 (2 is the adaptive
one). +A0.3 will set that the next samples are shot when the current ones
differ in color by that amount (I think the difference from black to white
is 3, 1 for each channel of rgb). You can lose lower values (+A0.01) for
more detailed settings, but it will only shoot up till the maximum amount of
samples you set, which are set with +R2. The value after R refers to the
level of sampling, not the actual amount of samples. On antialiasing method
1, +R2 sets 4 samples, whereas method 2 has 25. On level 5, method 1 has 25
samples, method 2 has 1089.
You might want to read section 3.1.2.8.4 of the docs (or just search for
"antialias") for more detailed information.
Regards,
Tim
--
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
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>> Is there a way to specify mipmaps in povray or can povray do it by
>> itself?
>
> You probably don't want mipmapping alone, because all by itself it's
> pretty useless (well, not useless, but it causes a very visible abrupt
> change at the places where the mipmap level changes). What you want
> is trilinear interpolation.
> Unfortunately POV-Ray does not support that. There are a couple of
> problems implementing trilinear interpolation in a raytracer. They can
> probably be solved, but it's not as trivial as in a scanline renderer.
Trilinear filtering is what i asked for. Because of the depedency of
mipmapping i just mentioned this one. If povray would support mipmapping
then trilinear filtering would be naturally there i think.
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> Antialiasing doesn't help too much when there are dozens of imagemap
> pixels in one result image pixel. It helps a bit, but does not give
> such a good result as trilinear interpolation.
Trilinear between what? The four corners of the pixel? You'll lose some
information then (just imagine: 4 black pixels on the texture with white in
between! *gosh* :-)
But seriously, what would you want to interpolate amongst? I guess,
depending on the detail of the texture and how much information you'd want
to place on a single pixel, downsampling it before using it (a la
mipmapping) is the best way to go. Generally though, like when you're
working with procedural textures, antialiasing is really the only way out,
unless script/program something new. Especially when we're talking about a
newbie. :-)
Regards,
Tim
--
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
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