I made a candle lit with an emission media.
When the background is black the flames look right, but as soon as I
add the candle to my scene the fire looks too clear, even if I
increase the amount of emission. What should I do? 
Should I add absorption or scattering media to the fire ?

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Jonathan Rafael Ghiglia wrote:
> 

> I made a candle lit with an emission media.
> When the background is black the flames look right, but as soon as I
> add the candle to my scene the fire looks too clear, even if I
> increase the amount of emission. What should I do?
> Should I add absorption or scattering media to the fire ?
	The easiest solution (at least if you're using unix) is to download
mPov and use emission mehtod 2. The not-so-easy solution is to add an
absorbing media, see the mPov page for an example of this method (and an
explanation of why emission method 2 is better).

	The mPov page:
http://www.enst.fr/~jberger/mpov/mpov.html


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* Settle for a good fantasy.    * http://www.enst.fr/~jberger
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<jbe### [at] enstfr> wrote:

> 	The easiest solution (at least if you're using unix) is to download
> mPov and use emission mehtod 2. The not-so-easy solution is to add an
> absorbing media, see the mPov page for an example of this method (and an
> explanation of why emission method 2 is better).

Another reason your method is better: if you have a patterned and 
colored density instead of a grayscale one, you will need to specify 
multiple media statements with different density colors instead of 
putting both emitting and absorbing in one. This is even worse than the 
case you showed, with a grayscale density. Of course, using separate 
media statements *is* more powerful, just harder to do what is usually 
wanted...

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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"Chris Huff" wrote:
> if you have a patterned and colored density instead of a
> grayscale one, you will need to specify multiple media
> statements with different density colors instead of
> putting both emitting and absorbing in one.

Why is this so bad? It takes up a bit more text, but using the method I've
described in povray.advanced-users it's very easy to control.

I haven't tried emission method 2. Can it do thick black media and other
dark colors?
I assume not, since it's emission after all? Anyway, the method I've
described can be used easily to make both light and dark colors. There's the
usual rgb vector *plus* a value that controls opacity.

> This is even worse than the case you showed, with a
> grayscale density. Of course, using separate media
> statements *is* more powerful, just harder to do what
> is usually wanted...

A bit more inconvenient, but not really harder... :)

Rune
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In article <3a3be2d5@news.povray.org>, "Rune" <run### [at] inamecom> 
wrote:

> Why is this so bad? It takes up a bit more text, but using the method 
> I've described in povray.advanced-users it's very easy to control.

Pretty much the only advantage is that it is shorter...but it seems like 
something that would fit in well as a built-in feature. However, I would 
probably have done it as an optional feature of emission media instead 
of a completely new type...

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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Chris Huff wrote:
> 

> Pretty much the only advantage is that it is shorter...but it seems lik
e
> something that would fit in well as a built-in feature. However, I woul
d
> probably have done it as an optional feature of emission media instead
> of a completely new type...
> 

	Well, it is an optional feature of emission media. I added two optional
keywords: emission_method and emission extinction that have meaning only
in the case of emission media. Specifying emission_method 1 is the same
as standard pov. I would have preferred a syntax similar to scattering
(emission { type, color, extinction }) but I haven't taken the time to
find out how to do this while staying compatible with the current
syntax.

To Rune:
	Of course there are ways to do something similar in straight pov and
you'll get more flexibility that way. But it is impossible to get
exactly the same effect and you need a lot more code to get results
especially if you've got a complex media (remember TonyB's mediagames
last spring?)


-- 


* Abandon the search for truth, * mailto:ber### [at] inamecom
* Settle for a good fantasy.    * http://www.enst.fr/~jberger
*********************************

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<jbe### [at] enstfr> wrote:

> 	Well, it is an optional feature of emission media. I added two optional
> keywords: emission method and emission extinction that have meaning only
> in the case of emission media.

Oh, ok...I thought it was more like "emission2".


> I would have preferred a syntax similar to scattering (emission { 
> type, color, extinction }) but I haven't taken the time to find out 
> how to do this while staying compatible with the current syntax.

Something like this should work:

Get_Token();
if(Token.TokenId == LEFT_CURLY_TOKEN)
{
    Unget_Token();
    Parse_Begin();
    ...parse your syntax here
    Parse_End();
}
else
{
    Unget_Token();
    ...parse standard syntax...
}

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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Chris Huff wrote:
> 

> Something like this should work:
> 

	Thanks, I'll try that


-- 


* Abandon the search for truth, * mailto:ber### [at] inamecom
* Settle for a good fantasy.    * http://www.enst.fr/~jberger
*********************************

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