The tutorial is On Darcy Johnston's website, under the tutorials 
section.
Here's the URL
http://www.geocities.com/SiliconValley/Sector/4317/

even following the tutorial, it took me a little while to realize what 
changes I would need for my own image but the results, I think, are very 
effective.
hope it helps

Steve

> Do you have the URL to that tutorial available to post here? TIA if 
you do
> because I'm sure people will want a look.
> Reason I said absorption <0.5,0.5,0.5> was because of the uncertainty 
about
> how it would fit in to begin with, so I was really just saying try
> absorption.
> 
> Bob
> 
> 
>

Post a reply to this message

Thanks, I didn't have that bookmarked.

"sacrofts" <sac### [at] tinyonlinecouk> wrote in message
news:39cf470b@news.povray.org...
The tutorial is On Darcy Johnston's website, under the tutorials section.
Here's the URL
http://www.geocities.com/SiliconValley/Sector/4317/

Post a reply to this message

Hi Tracers!

sacrofts schrieb:

> The tutorial is On Darcy Johnston's website, under the tutorials section.
> Here's the URL
> http://www.geocities.com/SiliconValley/Sector/4317/

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?

See you in Khyberspace!

Yadgar

Post a reply to this message

> 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?
> 

I'm beginning to wonder whether this effect is what is supposed to 
happen to the light as it travels through the simulated atmosphere.  For 
a similar scene I'm working on, I'm afraid I cheated and used several 
light sources, one the source of the rising sun, another shadowless 
light to rim light the atmosphere and a bit of artistic license to add a 
second sun into the scene from behind the viewer (well I'm not doing 
earth!!) But I guess there's no harm in making use of shadowless lights 
in this way.

Maybe some control over the contrast could be gained by using a 
color_map on your spherical density, this should simulate a thinning of 
the atmosphere from the planet's surface to the atmosphere's edge (index 
1.0 on the color_map).

One thing my own image is lacking is a descent glow over the planet's 
limb, any ideas?

Steve
website being built:
http://website.lineone.net/~sacrofts/home.htm

Post a reply to this message

>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

Post a reply to this message

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

Post a reply to this message

Bill DeWitt wrote:
> 
> ...but I wanted Ken to note the proper way to indent and arrange
> code.

You talking to me boy ?

I will continue to produce my POV-Ray code as I see fit. I will not
conform. I don't want to and I don't have to.

-- 
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

Post a reply to this message