"hughes b" <omn### [at] charternet> wrote in message
news:3d52c1e0$1@news.povray.org...
> "Christopher James Huff" <chr### [at] maccom> wrote in message
> news:chr### [at] netplexaussieorg...
> > In article <3d528e71@news.povray.org>,
> >  "David Wallace" <dar### [at] earthlinknet> wrote:
> >
> > > I am testing an emission media for use as lava.  The problem is, I am
> > > getting a solid white ball in my test sphere:
> >
> > That's just because the media is too bright, all three colors go above 1
> > so the color gets clipped to pure white in the final image. Reduce the
> > value given to emission, try 0.01 or 0.05 and adjust until you get what
> > you want.
>
> Actually, having tried it out here, I see that the whole media statement
> could be trouble for this lava idea. Not sure what the end result wanted
is
> exactly but that spherical pattern for density is all wrong, seems to me
> anyway. The index at 0 is the outside and 1 is inside. Could think of it
as
> a Earth, having [0 rgb 1] being the core and [1 rgb 0] being the outer
> atmosphere where it meets space. frequency -1 reverses the order so I used
> that.
>
> Also a couple things to note as well, method 3 intervals are done
> automatically-- unless you really want to override that-- and absorption
> could be needed too. No idea why ior 1.4 is there but David has his
> reasons...
>
> I could go on... (as i try stuff with it here)
>
> How about that amount of empty space and the turbulence? Seems to me the
> media would only be a sparkling mass and not solid. I think the amount of
> solidness diminishes a lot with that turbulence. And I tried emission 0.3
> absorption 0.2 which was okay-looking, as long as turbulence is 0.2 or
less.
> If more is used the frequency must be increased, or better yet, scale of
the
> density or a different object used than is now.
>
> Interestingly enough, the media can change drastically as scale,
turbulence,
> frequency are used differently. The spherical pattern is pretty special as
> it is anyway. I kind of knew all this already, of course  :-)  It isn't
real
> good with frequency, I guess, since by design it is only a unit size
without
> a repetition of itself to all other points in POV-space unlike most other
> patterns.
>
> Maybe the idea was to get a single textured appearance for other things
than
> that sphere, David will have to confirm this before I think it is
pointless
> to try and use the density_map as it currently stands. Oh... perhaps it
was
> intended to have transparent places with it overlaid into a part of a
scene?
> I should have thought of that, if so.
>
>
>
What I am trying to simulate is lava, a molten liquid, with an interior
consistent with a (dense and viscous) liquid.  The glow (emission) comes
from the extreme temperature.  I really need a bright, turbulent emission
media, similar to fire but more liquid in appearance (hence the ior).

The bright core is in the center (map entry 0) with a mostly clear periphery
(map entry 1), like fire.  Only the 0.00-0.02 part of the map has an entry
higher than 1; the vast majority, 0.25-1.00, is transparent.  This should
not result in a white sphere.  Actually, the lava jet I am simulating
consists of mostly stretched spheres but I need the media right before
continuing here.

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