Yadgar wrote:
> 
> 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?
> 

you can specify a location and radius, for some other parameters have a look at:

http://www.schunter.etc.tu-bs.de/~chris/etexture.html

(there are no black_hole samples there yet, but i'm working on an extension of
that section)

[...]
> 
> 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!
> 

I think the resolution you mentioned is perfectly enough for a first try, if the
height of the mountains is negligible you could also consider a bump_map,
although i don't know how it would look.

[...]
> 
> 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!

IMO 200 km is far to high and i also remember most real photos having less high
atmosphere.  

Christoph

--
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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