This is my first post and I'm fairly new to POV-Ray. Hello.

I'm modeling the Earth and I want the water specular reflection
color to *not* be the blue of the imagemap's water area, but
greyish instead, as it is in reality. The sun reflects mostly off the
surface, and since water is colorless the reflection itself should
be primarily the color of the incoming light. Plus violet, blue,
and green wavelengths are being selectively scattered out by
the atmosphere so it is actually slightly golden:

http://earth.jsc.nasa.gov/lores.cgi?PHOTO=STS036-075-024

The way I've been doing it so far is to do two separate renders
and combine them in post-processing. One render is three
nested spheres: Earth, clouds, and atmosphere; and the other I
render just the Earth sphere and cloud sphere using two all
black imagemaps - one with a land mask in the alpha channel
(the Earth sphere) and the other with a cloud mask in the alpha
channel (the cloud sphere). I get rid of the atmosphere sphere
then change the sunlight color to a pale gold. The render will be
all black with just the specular reflection showing, minus the
land and areas shaded by clouds.

I combine the two using Paint Shop Pro's 'screen' blend.

I'd much prefer to do this all in POV-Ray because I'd like to
animate it and don't want to have to post-process each frame.

I need to know if there is a way to change the specular
reflection color by whatever means POV-Ray has at its
disposal.

Regards,

Mike

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"Michael Smith" <s64### [at] worldnetattnet> wrote in message
news:3c7abd0b$1@news.povray.org...
> This is my first post and I'm fairly new to POV-Ray. Hello.

Hello back, and welcome.

> I'm modeling the Earth and I want the water specular reflection
> color to *not* be the blue of the imagemap's water area, but
> greyish instead, as it is in reality. The sun reflects mostly off the
> surface, and since water is colorless the reflection itself should
> be primarily the color of the incoming light.

Well, I'm not sure I can be of any help to you.  Thing is, specular
reflection is already the light source color unless the material reflecting
it back is metallic.  So I don't understand why you think it is blue.
Sorry.

The major problem with that and what you want to do is probably that the
highlight will blend with the background pigment, therefore it takes a light
color lacking in the object color to prevent the blending.  I just don't
have an idea for you, only trying to find out if that is the trouble.  And
if so, reflection alone, without highlights, might be the easy answer.  Not
sure.

bob h

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bob h wrote in message <3c7aef98@news.povray.org>...

>Well, I'm not sure I can be of any help to you.  Thing is, specular
>reflection is already the light source color unless the material
>reflecting it back is metallic.  So I don't understand why you think
>it is blue. Sorry.

Perhaps poor wording on my part, Bob...

>The major problem with that and what you want to do is probably
>that the highlight will blend with the background pigment,

Exactly. That's what I want to change somehow.

Take that photo I linked to - if POV-Ray ran the universe the water
reflection would be various lighter shades of the *apparent* color
of the water (blue) rather than the actual color (none) of the water.

What I need to do is find a way to make POV-Ray mimic water
reflections.

>therefore it takes a light color lacking in the object color to
>prevent the blending.

Yes, but that would make the rest of the image look wrong. You'd
need a yellow-orange light source color to cancel out the blue.

>And if so, reflection alone, without highlights, might be the easy
>answer. Not sure.

I think any reflection type I use will take on the color of the
imagemap. I wasjust wondering if there was any way to change
this.

Regards,

Mike

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In article <3c7af94b@news.povray.org>,
 "Michael Smith" <s64### [at] worldnetattnet> wrote:

> Take that photo I linked to - if POV-Ray ran the universe the water
> reflection would be various lighter shades of the *apparent* color
> of the water (blue) rather than the actual color (none) of the water.

No...you're artificially coloring the surface of the water. POV can't 
read your mind...


> What I need to do is find a way to make POV-Ray mimic water
> reflections.

Have you tried using reflection instead? Or just very tight specular 
highlights?


> I think any reflection type I use will take on the color of the
> imagemap. I wasjust wondering if there was any way to change
> this.

Reflection will only take the color of the pigment if you use 
"reflect_metallic" (MegaPOV) or put "metallic" in the reflection {} 
block (POV 3.5).

Water isn't usually done by making a blue, shiny texture...though if you 
are doing the planet earth I guess you don't have a lot of choice. But 
the highlights and reflections shouldn't be causing you problems...by 
default, they do not take the color of the surface.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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Take a look at
http://www-public.tu-bs.de:8080/~y0013390/pov/water/index.html
for a good tutorial on creating realistic water.

-- 
signature{
  "Grey Knight" contact{ email "gre### [at] yahoocom" }
  site_of_week{ url "http://digilander.iol.it/jrgpov" }
}

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Recently I wrote a little piece of code that you can control specular colour
with... So, sure it's possible in Pov.

Hugo

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Hugo <hua### [at] post3teledk> wrote in message news:3c7b7653@news.povray.org...
> Recently I wrote a little piece of code that you can control specular
colour
> with...


Would you mind sharing it?

 -Shay

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Christopher James Huff wrote in message ...

[Edited]

>No...you're artificially coloring the surface of the water. POV can't
>read your mind...
>
>Reflection will only take the color of the pigment if you use
>"reflect_metallic" (MegaPOV) or put "metallic" in the reflection {}
>block (POV 3.5).
>
>But the highlights and reflections shouldn't be causing you
>problems... by default, they do not take the color of the surface.

Yes, I understand implicitly the above three statements. The
reflection itself is the color of the lightsource (in this circumstance),
but the *net effect* when used on a blue imagemap is a reflection
that appears to be various values of blue...

>Water isn't usually done by making a blue, shiny texture...
>though if you are doing the planet earth I guess you don't have a
>lot of choice.

Now you're seeing the big picture! That's my limitation - I have to
use an imagemap. There's no other realistic option in this situation.

And that's the anology I was trying to make with the Space Shuttle
photo: the entire Earth surface, land AND water, will have to be an
imagemap, regardless of how physically unrealistic that is, and
reflections have to be superimposed onto it and made to *look*
real.

Given those limitations the POV-Ray run universe will not be able
to produce a realistic image (through no fault of its own). But the
situation limits me to using means that I know aren't realistic to get
the *impression* of realism. And in order to do that I just need to
be able to change one simple element (the specular reflection
appearance).

Like I originally mentioned, it can be done using two renders but I'd
prefer to find a way to do it in one to simplify animations.

>Have you tried using reflection instead? Or just very tight specular
>highlights?

Unless I'm missing something (remember I'm not an experienced
user) I have been using specular highlights. Maybe not "very tight"
though because I need to reproduce a specific appearance. I'll go
back again and try using just reflection, but I'm almost 100% that
I've tried it before and the results weren't what I wanted.

Regards,

Mike

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Hugo wrote in message <3c7b7653@news.povray.org>...

>Recently I wrote a little piece of code that you can control
>specular colour with... So, sure it's possible in Pov.

I'd like to be able to try it, if you wish to make it available.

Regrads,

Mike

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In article <3c7bf4b4$1@news.povray.org>,
 "Michael Smith" <s64### [at] worldnetattnet> wrote:

> >Have you tried using reflection instead? Or just very tight specular
> >highlights?
> 
> Unless I'm missing something (remember I'm not an experienced
> user) I have been using specular highlights. Maybe not "very tight"
> though because I need to reproduce a specific appearance. I'll go
> back again and try using just reflection, but I'm almost 100% that
> I've tried it before and the results weren't what I wanted.

Well, if you're using the "specular" keyword, those are specular 
highlights. ;-)

If you are trying to get a more spread-out highlight but reduce the 
blending, you might try reflection (which won't fade at all by default), 
possibly in combination with very tight specular, and give the texture a 
fine normal. The normal will break up the reflection of the sun, and 
actually simulate the effects of real highlights, but it will be more 
on/off...there will be areas that are highlighted and areas that are 
blue, with no blending between them.

If it doesn't have to be Earth, you could use a procedural texture and 
planet, and simulate the actual depth of the oceans, but it sounds like 
you want Earth.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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