Hi Christoph and all others!

Christoph Hormann schrieb:

> Realistic clouds from above are a difficult thing, you should try using warps
> for local changes of the pattern.  A turbulent bozo pattern is often a good
> start for cloud structures, but you could also try something else.
>

Warps? Never heard of them... how are they implemented?
<half an hour later...>
Ah, I found it in my PoV manual... from browsing through the "Warps" section, it
looks like the black_hole warp would meet my needs best... but how is the position
of each warp calculated respective to the actual texture on the object (which might
be scaled, rotated and translated afterwards)?

Do I have to scale etc. also the warp?

> Concerning the ground image map, i wonder whether the white parts are already
> clouds.  Furthermore i would suggest interpolation for getting rid of the grid
> structures and maybe you should consider real mountains with an isosurface.  (it
> looks somewhat flat right now)

Yes, I tried interpolate 2... looks much better! The white parts are not clouds, but
mountains covered with perennial snow (it's Eastern Siberia!)

Real mountains with an isosurface... you think of wrapping a heightfield around the
Earth sphere? I'm familiar with tools like DMesh or John Beale's ORB... they work
pretty well with asteroids, but with a real planet, I'm skeptical... I in fact have
an 8-bit greyscale heightfield of Earth's land surface on my harddisk, but as its
scale is still comparatively small (4320 by 2160 pixels) and the mountain ranges
visible here are in reality hardly higher than 3.000 meters (except for some single
volcanoes on Kamchatka, on the right limb), I would have to exaggerate the
heightfield's altitude dimension considerably to see any structures at all!

And as my machine is "only" an AMD K6-II-400 (currently slowed down to 300) with 64
MB RAM, I would not be able to make any use of much larger heightfields...

> The atmosphere looks good, but i wonder about the height ratio: if the clouds
> are 5 km high, the atmosphere seems to be visible up to more than 100 km which
> is too high IMO.
>

My atmosphere sphere (filled with blue media) in fact reaches 200 km high... but
when I compare my image to real orbital views, it looks correct to me!

See you in Khyberspace!

Yadgar

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