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Here's the result of some experimenting with atmospheric perspective in
POV. I've found this phenomenon to be one of the key elements in
"natural" or "out door" CG scenes which are particularly striking.
Terragen does a particularly good job of it.
However,rendering atmospheric perspective with any degree of control in
POV, has always been a challange to me beyond the basic ground fog(with
its characteristic bright horizon) or blue scattering media.
Anyone have any particular solutions they'd like to share?
Abe
Post a reply to this message
Attachments:
Download 'atm_perspec2.jpg' (16 KB)
Preview of image 'atm_perspec2.jpg'
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> Here's the result of some experimenting with atmospheric perspective in
> POV. I've found this phenomenon to be one of the key elements in
> "natural" or "out door" CG scenes which are particularly striking.
> Terragen does a particularly good job of it.
>
> However,rendering atmospheric perspective with any degree of control in
> POV, has always been a challange to me beyond the basic ground fog(with
> its characteristic bright horizon) or blue scattering media.
>
> Anyone have any particular solutions they'd like to share?
>
First of all: What exactly did you do? Did you use fog, or
media to create that atmosphere effect?
If you'll take a look into my gallery, you'll find an image in the
widescreen section "featuring" a silver woman statuette with
a red heart in her hand.
If you look closely at the horizon, the clouds do "haze away".
I did it using several ground-fogs with different fog_alt
settings. The color was adjusted to fit the actual color of the
horizon, and using some transmit (or filter, depends) helps
a lot to take care of the radioactive horizon. When using several
ground-fogs and high transmit values, you can get certain colors,
objects fading into that color when very distant, and eliminate
the glowing horizon to some degree.
--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html
Post a reply to this message
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> First of all: What exactly did you do? Did you use fog, or
> media to create that atmosphere effect?
My methods are patented and top secret. But if you promise not to
tell...
The atmosphere is an additive combination of a blue scattering media and
a blueish absorption media. The goal was to produce a blue-ing of the
shadow elements in the scene and a reddening of the light elements as a
function of distance. Ultimately the red and blue would merge in a
neutral gray.
> If you'll take a look into my gallery, you'll find an image in the
> widescreen section "featuring" a silver woman statuette with
> a red heart in her hand.
>
> If you look closely at the horizon, the clouds do "haze away".
>
> I did it using several ground-fogs with different fog_alt
> settings. The color was adjusted to fit the actual color of the
> horizon, and using some transmit (or filter, depends) helps
> a lot to take care of the radioactive horizon. When using several
> ground-fogs and high transmit values, you can get certain colors,
> objects fading into that color when very distant, and eliminate
> the glowing horizon to some degree.
I appreciate the manner of control you exhibit in that scene, but
I couldn't get the particular effect of coloration on light and dark
areas I was after with fog.
Abe
Post a reply to this message
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> The atmosphere is an additive combination of a blue scattering media and
> a blueish absorption media. The goal was to produce a blue-ing of the
> shadow elements in the scene and a reddening of the light elements as a
> function of distance. Ultimately the red and blue would merge in a
> neutral gray.
Interesting approach. How long does it actually take? I mean,
you've got stacked-planes as clouds (I guess), so using just
media wouldn't be a clever idea (again, just another educated
guess), but probably a plane as container?
Like to elaborate a bit more on your code?
--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html
Post a reply to this message
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Having tried to deal with the problem, I can appreciate your progress.
I am trying to illuminate a geographic heightfield with an overhead view
in such a way as to achieve the yellow of sunlight with the blue/purple
shadows common to the outdoors. My best effort so far is front illumination
with a yellow light source and back (shadows) illumination with a blue light
source.
Any suggestion?
Thanks,
Jim Julian
Below is a sample script.
------------------------------
#include "colors.inc"
camera{
orthographic
location <0, .275, 0>
right<3.65, 0, 0>
up <0, 3.65, 0>
look_at 0
angle 0
}
light_source { < -30, 30, 1> color rgb < 1.35, 1.35, 1.05 > } /* light
*/
light_source { < 30, 30, 1> color rgb < 0.75, 0.75, 1.00 > } /* shadow
*/
height_field {
tiff "c:\Temp\Eliz_Povray\rgbimg1-vf.tif"
pigment { White}
translate <-.5, -.5, -.5>
scale <1, 0.05, 1>
rotate <0, 0, 0>
}
----------------------------
Abe wrote:
>> First of all: What exactly did you do? Did you use fog, or
>> media to create that atmosphere effect?
>
>My methods are patented and top secret. But if you promise not to
>tell...
>The atmosphere is an additive combination of a blue scattering media and
>a blueish absorption media. The goal was to produce a blue-ing of the
>shadow elements in the scene and a reddening of the light elements as a
>function of distance. Ultimately the red and blue would merge in a
>neutral gray.
>
>> If you'll take a look into my gallery, you'll find an image in the
>> widescreen section "featuring" a silver woman statuette with
>> a red heart in her hand.
>>
>> If you look closely at the horizon, the clouds do "haze away".
>>
>> I did it using several ground-fogs with different fog_alt
>> settings. The color was adjusted to fit the actual color of the
>> horizon, and using some transmit (or filter, depends) helps
>> a lot to take care of the radioactive horizon. When using several
>> ground-fogs and high transmit values, you can get certain colors,
>> objects fading into that color when very distant, and eliminate
>> the glowing horizon to some degree.
>
>I appreciate the manner of control you exhibit in that scene, but
>I couldn't get the particular effect of coloration on light and dark
>areas I was after with fog.
>
>Abe
>
Jim Julian
Post a reply to this message
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I'm just interjecting here, having come across this thread without reading
the rest of it.
Most common method for this kind of lighting is to use a 'shadowless' light
source with the daytime blue coloring, that way it doesn't cast any shadows
that would interfere with the main light source. That might require
adjustment to the light colors since it mixes the two together.
Your scene setup almost prevents any possibility atmospheric effects due to
its camera location in relationship to the landscape object.
"Jim" <jul### [at] preferred com> wrote in message
news:web.3de42c42ff0ef26692e3424a0@news.povray.org...
>
> I am trying to illuminate a geographic heightfield with an overhead view
> in such a way as to achieve the yellow of sunlight with the blue/purple
> shadows common to the outdoors. My best effort so far is front
illumination
> with a yellow light source and back (shadows) illumination with a blue
light
> source.
> Any suggestion?
> Below is a sample script.
> ------------------------------
> #include "colors.inc"
> camera{
> orthographic
> location <0, .275, 0>
> right<3.65, 0, 0>
> up <0, 3.65, 0>
> look_at 0
> angle 0
> }
> light_source { < -30, 30, 1> color rgb < 1.35, 1.35, 1.05 > } /*
light
> */
> light_source { < 30, 30, 1> color rgb < 0.75, 0.75, 1.00 > } /*
shadow
> */
> height_field {
> tiff "c:\Temp\Eliz_Povray\rgbimg1-vf.tif"
> pigment { White}
> translate <-.5, -.5, -.5>
> scale <1, 0.05, 1>
> rotate <0, 0, 0>
> }
> ----------------------------
Post a reply to this message
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To: hughes,b
Thanks for the idea. Just for the record, I'm reviewing my physics/optics
in regard to the phenomenon and, will, if possible use Povray to emulate
light. Failing that I will try your idea.
Jim
hughes, b. wrote:
>I'm just interjecting here, having come across this thread without reading
>the rest of it.
>
>Most common method for this kind of lighting is to use a 'shadowless' light
>source with the daytime blue coloring, that way it doesn't cast any shadows
>that would interfere with the main light source. That might require
>adjustment to the light colors since it mixes the two together.
>
>Your scene setup almost prevents any possibility atmospheric effects due to
>its camera location in relationship to the landscape object.
Post a reply to this message
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