POV-Ray : Newsgroups : povray.binaries.images : Afghan Sunrise (133K) - problem with star background : Re: Afghan Sunrise (133K) - stars now correct, but surface in twilight Server Time
20 Aug 2024 06:19:02 EDT (-0400)
  Re: Afghan Sunrise (133K) - stars now correct, but surface in twilight  
From: Yadgar
Date: 27 Sep 2000 22:22:50
Message: <39D23BB6.ABC2D76B@ndh.net>
Hi Tracers!

Mark Wagner schrieb:


> >Yes, I tried absorption rgb <1, 0.5, 0> (according to my scattering rgb<0,
> 0.5, 1> and reduced this filter, not translucency to 0... but Earth's
> surface still
> >remains dull and low in contrast! Also in Darcy's tutorial, I didn't find
> anything about avoiding this effect... I browsed through the "finish"
> section of the
> >PoV-Ray manual, but it was also no help to me... is it avoidable at all or
> is it an essential deficiency of raytracing?
>
> Try increasing the "diffuse" component of the finish of the planet's surface
> to something in the 2.0 to 6.0 range.
>
> Mark

Thank you all for your advice, but in the meantime I found out, that in my
recent Iran/Afghanistan-from-orbit scene the (invisible, I commented out the
lensflare for convenience) sun was in fact very low, so that Earth surface just
could not be really bright.

I then moved the camera several dozen latitude degrees eastward into noon
sunlight over Eastern Siberia, and now I got the desired result!

Now I'm fiddling around with various texture patterns and noise modifiers to get
halfway realistic cloud swirls. The cloud layer is in fact a third concentric
sphere around my Earth, its surface 0.005 units (5 kms in my chosen scale) above
Earth surface, a comparatively simple color black-and-white (with a not too soft
transition between) map with filter values counter-corresponding to brightness
(black=1, white 0), so that the Earth surface is only hidden by the white clouds
(which cast nice shadows) ... at least, I found out that irrespective of
distribution patterns the white cloud areas need some relief to emulate the
cumuli structures, so I also have to add a bumpmap...

More on my cloud experiments later!

See you in Khyberspace!

Yadgar


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