"Xplo Eristotle" <inq### [at] unforgettablecom> wrote in message
news:39CABB99.A5937937@unforgettable.com...
| Margus Ramst wrote:
| >

| > >
| > > But whatever scattering mode I use, I never get the blue gradient
| > > atmosphere seam along the horizon familiar from real images shot from
| > > orbit...  can anyone here help me further?
| > >
| >
| > The correct scattering type for a (clear) atmosphere is probaby Raleigh
| > (type 4). The atmosphere gets thinner at higher altitudes, so perhaps
you should
| > also simulate that (density with "onion" or "spherical" pattern). And
for the
| > amosphere to be blue, you obviously have to tweak the colour of
emission,
| > scattering, etc.
|
| IRL, the blue comes from wavelength-dependent scattering. POV still
| doesn't do this (although someone was working on a patch some months
back).
|
| Of course, you could try to fake it.

Which means use a density_map having a color shift.  I've done that, and it
can work but you might find there is difficulty in getting the color to show
while also thinning the media out.  I used a fairly large blue value
compared to the red and green because it seemed relational.  In other words,
if the red and green were 0.05 and blue were only 0.5 chances are it won't
be very blue compared to if it were 10.  Or if the blend isn't being allowed
for to give blue only zone, i.e. [0 blue 0] [0.1 blue 1] can remain all blue
while fading toward the outer edge but not [0 blue 1] [0.1 rgb 1].

Bob

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