Does anyone know how to map a "stars.inc" starfield
onto the sky sphere

Regards RonN

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>Does anyone know how to map a "stars.inc" starfield
>onto the sky sphere


Render it and use it as a texture man

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You can not use a texture in a sky_sphere statement.

    You can on the other hand copy the pigment portion
out of which ever star type you want and use that in a
pigment statement with the sky_sphere.

There is only one thing you may include and that is pigments.
You may not use or do the following with sky_spheres:

1.)  finish's
2.)  textures
3.)  normals
4.)  interiors
5.)  halo's
6.) use multiple copies of it
7.) apply csg's to it
8.) give it away to friends

or anything else your probably think I missed.

Remember the sky_sphere is a virtual object and has
no real world physical characteristics.
(hum! real world in a computer?)
It's basically a glorified background light source.

Hope that clears things up for you.

Happy raytracing.

K.Tyler

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>    You can not use a texture in a sky_sphere statement.


whoops, watch me feel stupid :)

>Hope that clears things up for you.


definitely :)

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sBecaseu of the shortcomings of the Sky_sphere I use more outdated
methods, I declare a unit sphere and sacel it big, making it hollow so I
can use fog and halos and what not.  The only pitfall is that your
objeccts can cast shadows on it but since my scenes don't put the camera
near any lightsource, I rarely run into the problem. Playing with the
diffuse and brilliance values can help avoid this as well

Josh English
eng### [at] spiritonecom
www.spiritone.com/~english

K. Tyler wrote:

>     You can not use a texture in a sky_sphere statement.
>
>     You can on the other hand copy the pigment portion
> out of which ever star type you want and use that in a
> pigment statement with the sky_sphere.
>
> There is only one thing you may include and that is pigments.
> You may not use or do the following with sky_spheres:
>
> 1.)  finish's
> 2.)  textures
> 3.)  normals
> 4.)  interiors
> 5.)  halo's
> 6.) use multiple copies of it
> 7.) apply csg's to it
> 8.) give it away to friends
>
> or anything else your probably think I missed.
>
> Remember the sky_sphere is a virtual object and has
> no real world physical characteristics.
> (hum! real world in a computer?)
> It's basically a glorified background light source.
>
> Hope that clears things up for you.
>
> Happy raytracing.
>
> K.Tyler

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Josh English <eng### [at] spiritonecom> wrote:
: sBecaseu of the shortcomings of the Sky_sphere I use more outdated
: methods

  Shortcomings? I don't understand why do you need complete textures in the
sky_sphere. finish and normal statements do nothing since the "sphere" is
at the infinity.

-- 
                                                              - Warp. -

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Nieminen Mika wrote:

> Josh English <eng### [at] spiritonecom> wrote:
> : sBecaseu of the shortcomings of the Sky_sphere I use more outdated
> : methods
>
>   Shortcomings? I don't understand why do you need complete textures in the
> sky_sphere. finish and normal statements do nothing since the "sphere" is
> at the infinity.

    The sky_sphere isn't really at infinity though. It's not even
a sphere. It just appears that way.

    In fact it's really everywhere in the scene something else isn't.
Sounds confusing but it's not. The method of implementing the
sky_sphere is similar to the projection of the camera. Rays of light
are projected into the scene from all directions, and anywhere they
do  not  hit an object, that pixel is then turned on using the pigments
color index for that location.

    That's why no finish, normal. or texturing options are allowed.
You can't have it reacting with reflected rays coming off the surfaces
of the objects in the scene or you would end up with all kinds of
visible unwanted effects. You could, in a manner of speaking,
think of it as a massive, located everywhere,  area light.

K.Tyler

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The main shortcoming is that you can't make it hollow, and it isn't hollow be
default, so Halos and Fog wont work. This may be different in 3.1, but I haven't
looked into that too much yet. Complete Textures aren't always necesary, but
I've been tempted to build clouds on the sky sphere and add a normal
statement...so I have to fake it. I realize that it's supposed to be a more
interesting background than the Background statement, but I think it would be
cool to be able to do more with it...imagine a sky that glows with ambience.....

Josh English
eng### [at] spiritonecom
www.spiritone.com/~english


K. Tyler wrote:

> Nieminen Mika wrote:
>
> > Josh English <eng### [at] spiritonecom> wrote:
> > : sBecaseu of the shortcomings of the Sky_sphere I use more outdated
> > : methods
> >
> >   Shortcomings? I don't understand why do you need complete textures in the
> > sky_sphere. finish and normal statements do nothing since the "sphere" is
> > at the infinity.
>
>     The sky_sphere isn't really at infinity though. It's not even
> a sphere. It just appears that way.
>
>     In fact it's really everywhere in the scene something else isn't.
> Sounds confusing but it's not. The method of implementing the
> sky_sphere is similar to the projection of the camera. Rays of light
> are projected into the scene from all directions, and anywhere they
> do  not  hit an object, that pixel is then turned on using the pigments
> color index for that location.
>
>     That's why no finish, normal. or texturing options are allowed.
> You can't have it reacting with reflected rays coming off the surfaces
> of the objects in the scene or you would end up with all kinds of
> visible unwanted effects. You could, in a manner of speaking,
> think of it as a massive, located everywhere,  area light.
>
> K.Tyler

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Josh English wrote:

> The main shortcoming is that you can't make it hollow, and it isn't hollow be
> default, so Halos and Fog wont work. This may be different in 3.1, but I haven't
> looked into that too much yet. Complete Textures aren't always necesary, but
> I've been tempted to build clouds on the sky sphere and add a normal
> statement...so I have to fake it. I realize that it's supposed to be a more
> interesting background than the Background statement, but I think it would be
> cool to be able to do more with it...imagine a sky that glows with ambience.....
>
> Josh English

    I didn't know about the hollow restrictions, but it makes
since if you think about the way the sky_sphere is
implemented. I'm sure every halo container in the scene
would light up like a christmas tree.

    I don't think the POV-Ray Team really meant it to be a major
feature. Instead I think it was created to facilitate a quick and
easy way to add a background to your scene. In the docs
they make a reference to the sky_sphere as an addition to the
old, and seldom used background feature. It's even decried in
the same section of the docs.

    You also stated  "...imagine a sky that glows with ambience....."

    By default  the sky_sphere has a finish of  ambient 1  diffuse 0.
    and this cannot be changed.  So you got your wish !

K.Tyler

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I have tried to recreate this, and I can't seem to do it. I do remember sky spheres
interfering with fog and atmosephere and halos but today they seem to be working...
odd that

Josh English
eng### [at] spiritonecom
www.spiritone.com/~english

K. Tyler wrote:

> Josh English wrote:
>
> > The main shortcoming is that you can't make it hollow, and it isn't hollow be
> > default, so Halos and Fog wont work. This may be different in 3.1, but I haven't
> > looked into that too much yet. Complete Textures aren't always necesary, but
> > I've been tempted to build clouds on the sky sphere and add a normal
> > statement...so I have to fake it. I realize that it's supposed to be a more
> > interesting background than the Background statement, but I think it would be
> > cool to be able to do more with it...imagine a sky that glows with ambience.....
> >
> > Josh English
>
>     I didn't know about the hollow restrictions, but it makes
> since if you think about the way the sky_sphere is
> implemented. I'm sure every halo container in the scene
> would light up like a christmas tree.
>
>     I don't think the POV-Ray Team really meant it to be a major
> feature. Instead I think it was created to facilitate a quick and
> easy way to add a background to your scene. In the docs
> they make a reference to the sky_sphere as an addition to the
> old, and seldom used background feature. It's even decried in
> the same section of the docs.
>
>     You also stated  "...imagine a sky that glows with ambience....."
>
>     By default  the sky_sphere has a finish of  ambient 1  diffuse 0.
>     and this cannot be changed.  So you got your wish !
>
> K.Tyler

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