POV-Ray : Newsgroups : povray.newusers : starfield anti-aliasing problem Server Time
14 Nov 2024 04:29:22 EST (-0500)
  starfield anti-aliasing problem (Message 1 to 7 of 7)  
From: Duke Nukem
Subject: starfield anti-aliasing problem
Date: 23 May 1999 05:21:03
Message: <3747b849.178051618@news.povray.org>
Here's my problem. I'm working on a space scene. It's all done, and I
want to use AA to make the ship look good. But, when I do that, the
starfield in the background virtually disappears. I can barely see the
stars, they're real dim because of the blending of AA. I tried
pre-rendering the background and using an image map, but it has no
effect. I'm using the stars.inc file included with POV (starfield1 to
be precise). Does anyone have any ideas how I can use AA, but still
make my stars look as good as they do without it? Or, am I stuck with
just not using AA? Thanks in advance.

Scott Holland


Post a reply to this message

From: Rick
Subject: Re: starfield anti-aliasing problem
Date: 23 May 1999 08:08:02
Message: <3747e192.0@news.povray.org>
I have had this, make your stars bigger, simple but works, erither that or
dont render with AA, get the imge into psp or the like and resample it down
a few %, that works well sometimes (especially on stars!)

Rick

Duke Nukem <non### [at] yobidness> wrote in message
news:3747b849.178051618@news.povray.org...
> Here's my problem. I'm working on a space scene. It's all done, and I
> want to use AA to make the ship look good. But, when I do that, the
> starfield in the background virtually disappears. I can barely see the
> stars, they're real dim because of the blending of AA. I tried
> pre-rendering the background and using an image map, but it has no
> effect. I'm using the stars.inc file included with POV (starfield1 to
> be precise). Does anyone have any ideas how I can use AA, but still
> make my stars look as good as they do without it? Or, am I stuck with
> just not using AA? Thanks in advance.
>
> Scott Holland


Post a reply to this message

From: Peter Popov
Subject: Re: starfield anti-aliasing problem
Date: 23 May 1999 09:24:01
Message: <3748f28a.5605044@news.povray.org>
On Sun, 23 May 1999 08:21:04 GMT, non### [at] yobidness (Duke Nukem) wrote:

>Here's my problem. I'm working on a space scene. It's all done, and I
>want to use AA to make the ship look good. But, when I do that, the
>starfield in the background virtually disappears. I can barely see the
>stars, they're real dim because of the blending of AA. I tried
>pre-rendering the background and using an image map, but it has no
>effect. I'm using the stars.inc file included with POV (starfield1 to
>be precise). Does anyone have any ideas how I can use AA, but still
>make my stars look as good as they do without it? Or, am I stuck with
>just not using AA? Thanks in advance.
>
>Scott Holland

AA screws starfields up because it takes several samples per pixels
and averages them to get the final pixel color, whereas only one or
two of these sample rays will hit a "star" (either texture or object).
So at +r3 stars usuallly get 1/9 or 2/9 or max 1/3 of their intended
brightness. The solution is to color the stars using a high value of
white like White*4.5, for example.

---------
Peter Popov
ICQ: 15002700


Post a reply to this message

From: Bob Hughes
Subject: Re: starfield anti-aliasing problem
Date: 23 May 1999 10:58:26
Message: <37480974.32DCDE84@aol.com>
Peter Popov wrote:
> 
> On Sun, 23 May 1999 08:21:04 GMT, non### [at] yobidness (Duke Nukem) wrote:
> 
> >Here's my problem. I'm working on a space scene. It's all done, and I
> >want to use AA to make the ship look good. But, when I do that, the
> >starfield in the background virtually disappears. I can barely see the
> >stars, they're real dim because of the blending of AA. I tried
> >pre-rendering the background and using an image map, but it has no
> >effect. I'm using the stars.inc file included with POV (starfield1 to
> >be precise). Does anyone have any ideas how I can use AA, but still
> >make my stars look as good as they do without it? Or, am I stuck with
> >just not using AA? Thanks in advance.
> >
> >Scott Holland
> 
> AA screws starfields up because it takes several samples per pixels
> and averages them to get the final pixel color, whereas only one or
> two of these sample rays will hit a "star" (either texture or object).
> So at +r3 stars usuallly get 1/9 or 2/9 or max 1/3 of their intended
> brightness. The solution is to color the stars using a high value of
> white like White*4.5, for example.
> 
> ---------
> Peter Popov
> ICQ: 15002700

Yeah, that's a good solution. I use it all the time. Dropping the AA Depth
lesser is possible too, just not very good for the rest of the render. I
like the super intensity option best along with a increase in sizes of the
star pixel areas. Still, there's always the Alpha Channel masking method
too, just need to try it myself to see how it does.


-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/homepage.htm
 mailto://inversez@aol.com?Subject=PoV-News


Post a reply to this message

From: Duke Nukem
Subject: Re: starfield anti-aliasing problem
Date: 23 May 1999 23:20:36
Message: <3748b556.242842292@news.povray.org>
Thanks RIck! The resampling worked great. I render at an even multiple
of my final resolution. In my case 1024x768 for a final of 512x384. I
use Photoshop to knock it down and it looks great. I compared the
result to 512x384 AA and I couldn't tell the difference. The stars are
still a little dimmer, but at least they are clearly visible.

On Sun, 23 May 1999 11:52:43 +0100, "Rick" <kit### [at] dialpipexcom>
wrote:

>I have had this, make your stars bigger, simple but works, erither that or
>dont render with AA, get the imge into psp or the like and resample it down
>a few %, that works well sometimes (especially on stars!)
>
>Rick
>
>Duke Nukem <non### [at] yobidness> wrote in message
>news:3747b849.178051618@news.povray.org...
>> Here's my problem. I'm working on a space scene. It's all done, and I
>> want to use AA to make the ship look good. But, when I do that, the
>> starfield in the background virtually disappears. I can barely see the
>> stars, they're real dim because of the blending of AA. I tried
>> pre-rendering the background and using an image map, but it has no
>> effect. I'm using the stars.inc file included with POV (starfield1 to
>> be precise). Does anyone have any ideas how I can use AA, but still
>> make my stars look as good as they do without it? Or, am I stuck with
>> just not using AA? Thanks in advance.
>>
>> Scott Holland
>


Post a reply to this message

From: Rick
Subject: Re: starfield anti-aliasing problem
Date: 24 May 1999 22:06:56
Message: <3749f7b0.0@news.povray.org>
well now you have an image, post it :)

Rick

Duke Nukem <non### [at] yobidness> wrote in message
news:3748b556.242842292@news.povray.org...
> Thanks RIck! The resampling worked great. I render at an even multiple
> of my final resolution. In my case 1024x768 for a final of 512x384. I
> use Photoshop to knock it down and it looks great. I compared the
> result to 512x384 AA and I couldn't tell the difference. The stars are
> still a little dimmer, but at least they are clearly visible.
>
> On Sun, 23 May 1999 11:52:43 +0100, "Rick" <kit### [at] dialpipexcom>
> wrote:
>
> >I have had this, make your stars bigger, simple but works, erither that
or
> >dont render with AA, get the imge into psp or the like and resample it
down
> >a few %, that works well sometimes (especially on stars!)
> >
> >Rick
> >
> >Duke Nukem <non### [at] yobidness> wrote in message
> >news:3747b849.178051618@news.povray.org...
> >> Here's my problem. I'm working on a space scene. It's all done, and I
> >> want to use AA to make the ship look good. But, when I do that, the
> >> starfield in the background virtually disappears. I can barely see the
> >> stars, they're real dim because of the blending of AA. I tried
> >> pre-rendering the background and using an image map, but it has no
> >> effect. I'm using the stars.inc file included with POV (starfield1 to
> >> be precise). Does anyone have any ideas how I can use AA, but still
> >> make my stars look as good as they do without it? Or, am I stuck with
> >> just not using AA? Thanks in advance.
> >>
> >> Scott Holland
> >
>


Post a reply to this message

From: Xplo Eristotle
Subject: Photoshop tip (was: Re: starfield anti-aliasing problem
Date: 3 Aug 1999 20:30:50
Message: <37A789D6.6393@unforgettable.com>
Duke Nukem wrote:
> 
> Thanks RIck! The resampling worked great. I render at an even multiple
> of my final resolution. In my case 1024x768 for a final of 512x384. I
> use Photoshop to knock it down and it looks great. I compared the
> result to 512x384 AA and I couldn't tell the difference. The stars are
> still a little dimmer, but at least they are clearly visible.

If you're using Photoshop 4 or later, then after you antialias an image
through resampling like this, apply Sharpen once and then cut the filter
back to about 25-50% (depends on the image, experiment for best
results). That's just about enough to make your image look really crisp
without it being too sharp; it'd probably have brightened up those stars
a little bit as well.

-Xplo


Post a reply to this message

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.