Hi!

I have a photograph of a nice sky. I want to show the picture on a
sky_sphere with an image_map. How can I do this? I use map_type 1 but it
doesn't work. I only got a few strange big pixels on the skysphere.

Thanks a lot!!!

Post a reply to this message

On Fri, 2 May 2003 16:47:04 +0200, "Jos Tellings" <jte### [at] chellonl> wrote:
> Hi!
>
> I have a photograph of a nice sky. I want to show the picture on a
> sky_sphere with an image_map. How can I do this? I use map_type 1 but it
> doesn't work. I only got a few strange big pixels on the skysphere.
>
> Thanks a lot!!!

From what you wrote it seems you think that sky_sphere is not sphere but
rectangle for defining rectangular background of rectangular image. Not at all.
Sky_sphere is a sphere. With typical perspective camera you see only small
subsection of it. If you want add typical rectangular background you have a few
solutions, for example you can render your image in transparency in background
(+UA switch in options - see documentation) and then add background in image
manipulation application. You can as well look into screen.inc include file and
use macros from ther to locate some textured planes in fron of camera. It is
also described in manual. If you do not understand what manual-author wrote
about it feel free to ask again.

ABX

Post a reply to this message

"ABX" <abx### [at] abxartpl> wrote in message
news:0d15bv4lk80rhkr5u5b92igj9pg86ac9nv@4ax.com...
> On Fri, 2 May 2003 16:47:04 +0200, "Jos Tellings" <jte### [at] chellonl>
wrote:
> > Hi!
> >
> > I have a photograph of a nice sky. I want to show the picture on a
> > sky_sphere with an image_map. How can I do this? I use map_type 1 but it
> > doesn't work. I only got a few strange big pixels on the skysphere.
> >
> > Thanks a lot!!!
>
> From what you wrote it seems you think that sky_sphere is not sphere but
> rectangle for defining rectangular background of rectangular image. Not at
all.
> Sky_sphere is a sphere. With typical perspective camera you see only small
> subsection of it. If you want add typical rectangular background you have
a few
> solutions, for example you can render your image in transparency in
background
> (+UA switch in options - see documentation) and then add background in
image
> manipulation application.
This is a bad solution. The ambience of the sky is not reflected in my
picture then.

>You can as well look into screen.inc include file and
> use macros from ther to locate some textured planes in fron of camera. It
is
> also described in manual. If you do not understand what manual-author
wrote
> about it feel free to ask again.

When I use Screen_Plane I still get only a few gray pixels. I can not
recognize the sky at all.

  object { Screen_Plane ( pigment { image_map { jpeg
"sky.jpg" } },1,<0,0,0>,<1,1,0>) }

Set_Camera_Sky doesn't work either. Do you know what I'm doing wrong?

Thanks

> ABX

Post a reply to this message

Jos Tellings <jte### [at] chellonl> wrote in message
news:3eb39e2c$1@news.povray.org...
>
> "ABX" <abx### [at] abxartpl> wrote in message
> news:0d15bv4lk80rhkr5u5b92igj9pg86ac9nv@4ax.com...
> > On Fri, 2 May 2003 16:47:04 +0200, "Jos Tellings" <jte### [at] chellonl>
> wrote:
> > > Hi!
> > >
> > > I have a photograph of a nice sky. I want to show the picture on a
> > > sky_sphere with an image_map. How can I do this? I use map_type 1 but
it
> > > doesn't work. I only got a few strange big pixels on the skysphere.
<snip>

> > Sky_sphere is a sphere. With typical perspective camera you see only
small
> > subsection of it.

The sky is 360 degrees of space surrounding the earth. Your photo is only a
tiny portion of it as ABX is saying.  So when you apply it to the whole
sphere, what you see is a tiny piece of it blown up to monstrous
proportions.


> This is a bad solution. The ambience of the sky is not reflected in my
> picture then.

So what you really want is the whole 360 degrees, or at least the 180 that
are above the horizon...

Try this: in whatever image manipulation program you use, create a new image
doubling the size of your photo in both height & width.  Paste in your photo
upper left, then paste it again to lower left and flipping it. Then mirror
the left side to the right side, save it and use this on your sky_sphere
(map type 1).

If you're doing animation this probably won't work because it will leave
seams, but if you are creating a still, you should be able to
rotate/translate the sky_sphere to get your photo in the scene without the
seams showing and also get the proper ambience for your reflections and
radiosity.

If it's still too big, repeat the process with your saved version.  I've
done this before with acceptable results.

RG

P.S. This is all because a sky_sphere always maps the image once.  You could
alternately just create your own sky sphere and use the photo as an
image_map texture (without the once keyword) and scaling it until it tiles
to something usable, but the seams will probably be more noticable that way.

Post a reply to this message

"Jos Tellings" <jte### [at] chellonl> wrote in message
news:3eb39e2c$1@news.povray.org...
>

I get predictable results with:

sky_sphere{
  pigment{
    image_map{
      jpeg "sky.jpg" map_type 1
    }
  }
}

Can you post your source jpg in binaries.images or mail it to me?

Bare in mind that you will only be seeing a small section of your image and
that it will be pinched at the N and S poles. It sounds as though you are
seeing small defects in the original image magnified.

Post a reply to this message