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On Tue, 22 Apr 2003, Andrew Coppin wrote:
>> +a0.0 +am2 +r10 should be pretty good.
>
>It's just taken me ten minutes to work out what that does... (AA threshold =
>0 = always supersample, method = 2, depth = 10, i.e., 100 rays per pixel.)
>There are some people out there with very impressive powers of recall!
is that a gaussian function that is applied to calculate the anti-aliased
value of the pixel or simply the average of pixels within a 10 pixel radius.
Then again, are we talking a square of 10x10 and not a radius of 10 pixels?
>
>(From someone who has now MEMORISED the zillion-digit product key for my
>copy of Windows 2000 Advanced Server... what does that tell you???)
I could once spout out the first 100 digits of pi. At parties and such. I
seem to remember spending a lot of time talking to plants in dark corners
but then again, I am a Barclay ( see StarTrek ) clone. :)
>
>> See you in a few years then... ;-)
>
>Depends on what you wanna render doesn't it? ;-)
>
>Andrew.
Well .. I am gonna give it a try on a 10240x7680 pixel image. Should take a
week or so and a gig of RAM.
Dennis
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Christoph Hormann <chr### [at] gmx de> wrote:
> +a0.0 +am2 +r10 should be pretty good.
"+a0.0 +am2" should be enough for most difficult cases. If it's a very
difficult case, then add "+r4".
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
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In article <Pine.GSO.4.53.0304221425230.5704@blastwave>,
Dennis Clarke <dcl### [at] blastwaveorg> wrote:
> is that a gaussian function that is applied to calculate the anti-aliased
> value of the pixel or simply the average of pixels within a 10 pixel radius.
> Then again, are we talking a square of 10x10 and not a radius of 10 pixels?
This is antialiasing, not blur. We are supersampling a single pixel.
--
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/
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In article <3ea597e7@news.povray.org>, Warp <war### [at] tagpovrayorg>
wrote:
> Christoph Hormann <chr### [at] gmxde> wrote:
> > +a0.0 +am2 +r10 should be pretty good.
>
> "+a0.0 +am2" should be enough for most difficult cases. If it's a very
> difficult case, then add "+r4".
What is the point of using method 2 with a threshold of 0.0? You might
as well use non-adaptive antialiasing...these settings get rid of the
calculation savings of the adaptive method. This should be about the
same as rendering an oversized image without antialiasing and then
resizing it down. (in a decent graphics program, of course)
--
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/
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> What is the point of using method 2 with a threshold of 0.0?
Hmm... why didn't *I* notice that? 8-|
Andrew.
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Christopher James Huff wrote:
>
> What is the point of using method 2 with a threshold of 0.0? You might
> as well use non-adaptive antialiasing...these settings get rid of the
> calculation savings of the adaptive method. This should be about the
> same as rendering an oversized image without antialiasing and then
> resizing it down. (in a decent graphics program, of course)
If you scale down a larger render you can additionally reduce aliasing
artefacts by applying blurring filters before the scaling.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______
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On Tue, 22 Apr 2003, Christopher James Huff wrote:
>In article <Pine.GSO.4.53.0304221425230.5704@blastwave>,
> Dennis Clarke <dcl### [at] blastwaveorg> wrote:
>
>> is that a gaussian function that is applied to calculate the anti-aliased
>> value of the pixel or simply the average of pixels within a 10 pixel radius.
>> Then again, are we talking a square of 10x10 and not a radius of 10 pixels?
>
>This is antialiasing, not blur. We are supersampling a single pixel.
In what way is antialiasing within a single pixel different from blur of
a single pixel. They are essentially the same thing n'est pas? My thoughts
on this are that you can have a +r3 antialias approach in which a 3x3 grid
should be laid down within a single pixel and then the average of the RGB
values calculated at the center. The concept of blur would be the same yes?
Simply with a blur you would increase the resolution of the image by a factor
of 3 in each dimension and then calculate the average RGB values within a
central pixel from the surrounding 3x3 pixels. Is the real difference, if
any, that this is more like a digital convolution by using a comb filter
function with a 3x3 identity matrix ( all 1's ) and therefore the central
pixel value would be including its neighbors while anti-aliasing does not
include its neighbors at all? Is the sampling matrix that is used for the
average actually all 1's or is it 1/sqrt(2) on the corners and sqrt(2/3)
on the edges?
antialias matrix for 3x3 within a single pixel
+--------+--------+--------+
| | | |
| p | q | p | where p = 1/sqrt(2) and
| | | |
+--------+--------+--------+ q = sqrt(2/3)
| | | |
| q | 1 | q |
| | | |
+--------+--------+--------+
| | | |
| p | q | p |
| | | |
+--------+--------+--------+
I'm just thinking via my keyboard here ..
Dennis
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> In what way is antialiasing within a single pixel different from blur of
> a single pixel. They are essentially the same thing n'est pas? My
thoughts
> on this are that you can have a +r3 antialias approach in which a 3x3
grid
> should be laid down within a single pixel and then the average of the RGB
> values calculated at the center. The concept of blur would be the same
yes?
Not really, since with blurring, adjacent pixels would bleed into each
other.
- Slime
[ http://www.slimeland.com/ ]
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In article <3EA### [at] gmxde>,
Christoph Hormann <chr### [at] gmxde> wrote:
> If you scale down a larger render you can additionally reduce aliasing
> artefacts by applying blurring filters before the scaling.
This can be handled by a good scaling algorithm. There are many
possibilities...for example, the Mac program GraphicConverter offers
these scaling algorithms:
QuickDraw/Quartz
Bicubic
Bicubic with dither
Smooth
Box
Triangle
Bell
B-Spline
Sinus
Lanczos 3
Mitchell
Manually blurring won't help much here, if at all. It really only helps
with the "nearest neighbor" algorithm, which won't be used by any decent
graphics program and would be useless for removing aliasing. I doubt
there is any program that has a blur filter and which uses nearest
neighbor, and blurring the source image will probably just interfere
with these algorithms.
--
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/
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In article <Pine.GSO.4.53.0304221845420.6559@blastwave>,
Dennis Clarke <dcl### [at] blastwaveorg> wrote:
> In what way is antialiasing within a single pixel different from blur of
> a single pixel.
You can't blur a pixel, you need a set of pixels. The algorithm used is
somewhat similar, but the goal and result are different. Blurring
removes information from an image, spreading colors out across adjacent
pixels. Antialiasing adds data, coloring each pixel with the overall
color of the area it covers instead of a single point within that area,
and is not dependant on the colors of adjacent pixels. You can use an
antialiasing algorithm with a large image as input, but you will get a
smaller image as a result.
--
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/
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