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From: Doug Moses
Subject: Is this a bug or is it me?
Date: 3 Dec 2000 22:55:52
Message: <3a2b15c8$1@news.povray.org>
I am very new to POVRAY and I came across an interesting image when I was
creating a starfield plane in the Z direction. I populated it with a granite
color_map. I looked straight down the Z direction and got a weird result. Is
this me and I don't understand what I am doing or is this a strange render
bug? Shouldn't this be a seamless image with no distinguishing boundaries?
It is probably just me but I don't know how to explain it or correct it. I
am using Windows v3.1g. Any help will be greatly appreciated.

Thank you for your time.
Doug

Below is the code to this question.

camera
 {
  location <0,0,-5000>
  look_at <0,0,0>
 }

plane
 {
  <0,0,1>,5000
  texture
   {
    pigment
     {
      granite
      color_map
       {
        [5 rgb <0,2,5>]
        [.3 rgb 0]
       }
     }
   }
   finish {ambient 1}
 }


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From: Steve
Subject: Re: Is this a bug or is it me?
Date: 3 Dec 2000 23:19:25
Message: <slrn92m6p0.e98.steve@zero-pps.localdomain>
On Sun, 3 Dec 2000 21:57:07 -0600, Doug Moses wrote:

>Below is the code to this question.

Hi Doug, I havn't rendered this but some things look strange, 
I'll comment the code. 

camera
 {
  location <0,0,-5000>  // a lot of units. 
  look_at <0,0,0>
 }

plane
 {
  <0,0,1>,5000   // don't know what the ,5000 is doing there?
  texture        // probably better to use something like 
   {             // plane {z,5000  
    pigment      //        all the pigment stuff goes here
     {           //       }
      granite
      color_map
       {
        [5 rgb <0,2,5>]
        [.3 rgb 0]
//     Colour maps go from 0 to 1 ie:
//     colour_map 
//       {
//        [0 rgb <0,2,5>]
//        [0.1  rgb 0]
//        [1 rgb 0]       
       }
     }
   }
   finish {ambient 1}
 }

Hope some of that helps. 

-- 
Cheers
Steve              email mailto:ste### [at] zeroppsuklinuxnet

%HAV-A-NICEDAY Error not enough coffee  0 pps. 

web http://www.zeropps.uklinux.net/

or  http://start.at/zero-pps

  4:04am  up 54 days,  6:28,  2 users,  load average: 2.21, 1.55, 1.30


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From: Doug Moses
Subject: Re: Is this a bug or is it me?
Date: 3 Dec 2000 23:57:03
Message: <3a2b241f@news.povray.org>
Thanks for the quick response. I changed the code as you suggested and it
works great. The only thing is it is now just a granite plane. I was trying
to get a distant starfield image. I guess this is not the technique to use
for this effect. I also found out that the -5000 and 5000 numbers were the
key to this strange effect. When these numbers are low it is a uniform
pattern. When they are large this is when you get the distinct boundary
changes. I guess it is too far for the formula to work correctly.

Thanks for all of you help!
Doug

"Steve" <ste### [at] zeroppsuklinuxnet> wrote in message
news:slr### [at] zero-ppslocaldomain...
> On Sun, 3 Dec 2000 21:57:07 -0600, Doug Moses wrote:
>
> >Below is the code to this question.
>
> Hi Doug, I havn't rendered this but some things look strange,
> I'll comment the code.
>
> camera
>  {
>   location <0,0,-5000>  // a lot of units.
>   look_at <0,0,0>
>  }
>
> plane
>  {
>   <0,0,1>,5000   // don't know what the ,5000 is doing there?
>   texture        // probably better to use something like
>    {             // plane {z,5000
>     pigment      //        all the pigment stuff goes here
>      {           //       }
>       granite
>       color_map
>        {
>         [5 rgb <0,2,5>]
>         [.3 rgb 0]
> //     Colour maps go from 0 to 1 ie:
> //     colour_map
> //       {
> //        [0 rgb <0,2,5>]
> //        [0.1  rgb 0]
> //        [1 rgb 0]
>        }
>      }
>    }
>    finish {ambient 1}
>  }
>
> Hope some of that helps.
>
> --
> Cheers
> Steve              email mailto:ste### [at] zeroppsuklinuxnet
>
> %HAV-A-NICEDAY Error not enough coffee  0 pps.
>
> web http://www.zeropps.uklinux.net/
>
> or  http://start.at/zero-pps
>
>   4:04am  up 54 days,  6:28,  2 users,  load average: 2.21, 1.55, 1.30


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From: Steve
Subject: Re: Is this a bug or is it me?
Date: 4 Dec 2000 00:03:25
Message: <slrn92m9bk.erj.steve@zero-pps.localdomain>
On Sun, 3 Dec 2000 22:58:18 -0600, Doug Moses wrote:
>Thanks for the quick response. I changed the code as you suggested and it
>works great. The only thing is it is now just a granite plane. I was trying
>to get a distant starfield image. I guess this is not the technique to use
>for this effect. I also found out that the -5000 and 5000 numbers were the
>key to this strange effect. When these numbers are low it is a uniform
>pattern. When they are large this is when you get the distinct boundary
>changes. I guess it is too far for the formula to work correctly.

Chris Colefax has a galaxy include file/macro that you can use:

 http://www.geocities.com/SiliconValley/Lakes/1434/


-- 
Cheers
Steve              email mailto:ste### [at] zeroppsuklinuxnet

%HAV-A-NICEDAY Error not enough coffee  0 pps. 

web http://www.zeropps.uklinux.net/

or  http://start.at/zero-pps

  4:58am  up 54 days,  7:22,  2 users,  load average: 1.13, 1.03, 1.01


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From: Margus Ramst
Subject: Re: Is this a bug or is it me?
Date: 4 Dec 2000 08:36:19
Message: <3A2B9E49.4F2E91CC@peak.edu.ee>
Doug Moses wrote:
> 
> I am very new to POVRAY and I came across an interesting image when I was
> creating a starfield plane in the Z direction.
[snip]

What you're experiencing is a known bug with some patterns, such as granite,
bozo, turbulence etc. These patterns will start to act strangely at large
negative distances from the origin (e.g. -10000 for bozo, -10000/128 for
granite). A workaround is to translate your pattern in the positive direction.

-- 
Margus Ramst

Personal e-mail: mar### [at] peakeduee
TAG (Team Assistance Group) e-mail: mar### [at] tagpovrayorg
Home page http://www.hot.ee/margusrt


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From: Phil Clute
Subject: Re: Is this a bug or is it me?
Date: 4 Dec 2000 22:26:06
Message: <3A2C6062.6BFFF99F@tiac.net>
...and there's also Xstars.inc which has real-world(space)
constellations:
http://www.geocities.com/CapeCanaveral/Galaxy/8018/

-- 
Phil
...coffee?...yes please! extra sugar,extra cream...Thank you.


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From: Phil Clute
Subject: Re: Is this a bug or is it me?
Date: 4 Dec 2000 22:35:21
Message: <3A2C628B.B4F4306E@tiac.net>
Please post this sort of thing to povray.binaries.scene-files .
Also you should check out the povray.announce.frequently-asked-questions
for all the correct posting procedures. We like to keep things organized
so it's easier to find things later on when we need them.

-- 
Phil
...coffee?...yes please! extra sugar,extra cream...Thank you.


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From: Ken
Subject: Re: Is this a bug or is it me?
Date: 4 Dec 2000 22:38:49
Message: <3A2C640C.88D29828@pacbell.net>
Doug Moses wrote:
> 
> I changed the code as suggested and now I have a stable good looking
> starfield. Here is the modified code. I also attached my first image_map to
> the scene. Thanks for the tips and links everyone! I got the image_maps from
> http://www.btinternet.com/~consty/render/render_f.htm Wow this stuff is fun!

I am glad you got the help you need. Now we need to discuss the
news server posting guidelines. We insist that you do not post
binary attacments in a non binaries group on this news server.
You should have posted your POV-Ray scene file attachement in
the povray.binaries.scene-files group. The image, converted to
a compressed .jpg file (we try to keep them under 200k in size
when possible), should have been posted in the povray.binaries.
images group.

I encourage you to cancel your last message. You may then repost
your comments here with a mention of where to find the source
which you can then repost to the appropriate groups on this server.
Please also take the time to read the messages in the announcments
group. I have posted a "welcome to the news server" message that
details what the different groups are for and other guidelines
that will assist you in getting the most from this news server.

Thank you for your participation and your co-operation.

-- 
Ken Tyler - ken### [at] tagpovrayorg


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From: Doug Moses
Subject: Re: Is this a bug or is it me?
Date: 4 Dec 2000 23:06:33
Message: <3a2c69c9$1@news.povray.org>
Sorry for posting images to the wrong group. I am new an newsgroups too.
Here is the revised message without the attachments and I canceled my
previous posting.


-------------------------
I changed the code as suggested and now I have a stable good looking
starfield. Wow this stuff is fun!

Doug


"Doug Moses" <kdm### [at] homecom> wrote in message
news:3a2c5f65@news.povray.org...
> I changed the code as suggested and now I have a stable good looking
> starfield. Here is the modified code. I also attached my first image_map
to
> the scene. Thanks for the tips and links everyone! I got the image_maps
from
> http://www.btinternet.com/~consty/render/render_f.htm Wow this stuff is
fun!
>
> camera
>  {
>   location <0,0,5000>
>   look_at <0,0,0>
>  }
>
> plane
>  {
>   z,0
>   texture
>    {
>     pigment
>      {
>       crackle
>       color_map
>        {
>         [1 rgb <0,2,5>]
>         [.005 rgb 0]
>        }
>      }
>    }
>    finish {ambient 1}
>  }
>
>
> "Margus Ramst" <mar### [at] peakeduee> wrote in message
> news:3A2B9E49.4F2E91CC@peak.edu.ee...
> > Doug Moses wrote:
> > >
> > > I am very new to POVRAY and I came across an interesting image when I
> was
> > > creating a starfield plane in the Z direction.
> > [snip]
> >
> > What you're experiencing is a known bug with some patterns, such as
> granite,
> > bozo, turbulence etc. These patterns will start to act strangely at
large
> > negative distances from the origin (e.g. -10000 for bozo, -10000/128 for
> > granite). A workaround is to translate your pattern in the positive
> direction.
> >
> > --
> > Margus Ramst
> >
> > Personal e-mail: mar### [at] peakeduee
> > TAG (Team Assistance Group) e-mail: mar### [at] tagpovrayorg
> > Home page http://www.hot.ee/margusrt
>
>
>


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From: Phil Clute
Subject: Re: Is this a bug or is it me?
Date: 4 Dec 2000 23:19:33
Message: <3A2C6CEB.EA4E6353@tiac.net>
> Sorry for posting images to the wrong group. 
> ...I canceled my previous posting.

No big deal.

-- 
Phil
...coffee?...yes please! extra sugar,extra cream...Thank you.


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