 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Hi all!
I have a concern with radiosity and scattering media. I tried to find
previous info on this topic but did not get a clear answer. In a
full-radiosity scene, does scattering media react (= 'shine') to radiosity
rays? According to the following scene it appears not, and only the
extincion effect is visible, not the scattering itself.
Thanks for enlighting me!
#include "colors.inc"
#declare Radiosity=on;
global_settings {
assumed_gamma 1.0
max_trace_level 25
#if (Radiosity)
radiosity {
pretrace_start 0.04 // start pretrace at this size
pretrace_end 0.01 // end pretrace at this size
count 100 // higher -> higher quality (1..1600)
[35]
nearest_count 5 // higher -> higher quality (1..10) [5]
error_bound 0.6 // higher -> smoother, less accurate
[1.8]
recursion_limit 3 // how much interreflections are
calculated (1..5+) [3]
low_error_factor .5 // reduce error_bound during last
pretrace step
gray_threshold 0.0 // increase for weakening colors (0..1)
[0]
minimum_reuse 0.015 // reuse of old radiosity samples
[0.015]
brightness 1 // brightness of radiosity effects
(0..1) [1]
adc_bailout 0.01/2
normal on // take surface normals into account [off]
media on // take media into account [off]
}
#end
}
#default {
texture {
pigment {rgb 1}
#if (Radiosity)
finish {
ambient 0.0
diffuse 0.6
specular 0.3
}
#else
finish {
ambient 0.1
diffuse 0.6
specular 0.3
}
#end
}
}
// ----------------------------------------
camera {
right x*image_width/image_height
angle 50
location 0
look_at z
rotate 10*x
translate <0,0.75,-4>
}
sky_sphere {pigment {White}}
// ----------------------------------------
plane {y, -1 pigment {color 0.5*White}}
box
{
-0.5, 0.5
hollow
pigment {rgbt 1}
interior
{
ior 1.05
media
{
scattering {1, 2}
}
}
rotate -15*x + 30*y
}
Bruno
Post a reply to this message
Attachments:
Download 'mediarad.png' (9 KB)
Preview of image 'mediarad.png'
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Well, I seeked the web but not the documentation. It clearly stated in
"3.6.2.1.3 Scattering":
The scattering effect is only visible when light is shining on the media
from a light source.
So I re-formulate: how can I use scattering media in a full-radiosity scene?
Is it possible? What about the Cornell radiosity example if there is a
media-filled box in te room?
Bruno.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Bruno Cabasson nous apporta ses lumieres en ce 2007/09/12 08:19:
> Well, I seeked the web but not the documentation. It clearly stated in
> "3.6.2.1.3 Scattering":
>
> The scattering effect is only visible when light is shining on the media
> from a light source.
>
> So I re-formulate: how can I use scattering media in a full-radiosity scene?
> Is it possible? What about the Cornell radiosity example if there is a
> media-filled box in te room?
>
> Bruno.
>
Light been scattered by a scattering media will affect the radiosity, if "media
on" is set.
Radiosity ray are only affected by the extinction and never illuminate any media.
You can fake it, somewhat, by using an emiting media together with the
scattering media. Mostly work in relatively simple cases. Good with large
ambient surfaces "lighting" simple shapes.
--
Alain
-------------------------------------------------
Q. What's the difference between Batman and Bill Gates?
A. When Batman fought the Penguin, he won.
-- J. Levine
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Alain <ele### [at] netscape net> wrote:
> Bruno Cabasson nous apporta ses lumieres en ce 2007/09/12 08:19:
> > Well, I seeked the web but not the documentation. It clearly stated in
> > "3.6.2.1.3 Scattering":
> >
> > The scattering effect is only visible when light is shining on the media
> > from a light source.
> >
> > So I re-formulate: how can I use scattering media in a full-radiosity scene?
> > Is it possible? What about the Cornell radiosity example if there is a
> > media-filled box in te room?
> >
> > Bruno.
> >
> Light been scattered by a scattering media will affect the radiosity, if "media
> on" is set.
> Radiosity ray are only affected by the extinction and never illuminate any media.
>
> You can fake it, somewhat, by using an emiting media together with the
> scattering media. Mostly work in relatively simple cases. Good with large
> ambient surfaces "lighting" simple shapes.
>
> --
> Alain
> -------------------------------------------------
> Q. What's the difference between Batman and Bill Gates?
> A. When Batman fought the Penguin, he won.
> -- J. Levine
Thanks for your reply. Waiting for someone to answer, I made a few more
tries and tested the trick with emissive media. I don't find it very
satisfatory in that the object is illuminated, but emits light. In a
radiosity scene, it is preferable to avoid this.
I am trying another idea ...
Bruno
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Bruno Cabasson wrote:
>
> Thanks for your reply. Waiting for someone to answer, I made a few more
> tries and tested the trick with emissive media. I don't find it very
> satisfatory in that the object is illuminated, but emits light. In a
> radiosity scene, it is preferable to avoid this.
>
> I am trying another idea ...
Bruno,
You might try Alain's idea of faking it with other light_sources. You
need not worry about the other lights affecting the scene if you make a
light_group, like so:
/* begin pseudocode
light_group{
light_source{...}
light_source{...}
object{ media_object }
}
end pseudocode*/
The lights will only illuminate the media object, so you are free to try
different light_source settings to fake global illumination. The lights,
however, may cast shadows from unlit objects. Be aware of that.
Sam
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Samuel Benge <stb### [at] THIShotmailcom> wrote:
> Bruno Cabasson wrote:
> >
> > Thanks for your reply. Waiting for someone to answer, I made a few more
> > tries and tested the trick with emissive media. I don't find it very
> > satisfatory in that the object is illuminated, but emits light. In a
> > radiosity scene, it is preferable to avoid this.
> >
> > I am trying another idea ...
>
> Bruno,
>
> You might try Alain's idea of faking it with other light_sources. You
> need not worry about the other lights affecting the scene if you make a
> light_group, like so:
>
> /* begin pseudocode
> light_group{
> light_source{...}
> light_source{...}
> object{ media_object }
> }
> end pseudocode*/
>
> The lights will only illuminate the media object, so you are free to try
> different light_source settings to fake global illumination. The lights,
> however, may cast shadows from unlit objects. Be aware of that.
>
> Sam
This is exactly what I was thinking of and experimenting. The last scene is
currently rendering ...
Bruno
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Here is a quick try with low radiosity settings and a first attempt to the
material of the box. Needs tuning and improvements, especially a density
function for the media in order to give granularity, and the normal also
needs to be re-worked.
The scene is lit by a 2-color dome (Yellow/Blue which combine into Gray with
radiosity), and the media box is lit by 2 sets of 50 randomly positionned
light_sources (Yellow on the left, Blue on the right) within a light_group.
The circle of small balls is just decoration.
I intend to get an acceptable translucent Wax material. Here, the lighting
is not suitable to show translucency.
Bruno
Post a reply to this message
Attachments:
Download 'mediarad.png' (111 KB)
Preview of image 'mediarad.png'
|
|
| |
| |
|
|
|
|
| |
| |
|
|
My last experiment.
Regards.
Post a reply to this message
Attachments:
Download 'mediarad.jpg' (34 KB)
Preview of image 'mediarad.jpg'
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Bruno Cabasson nous apporta ses lumieres en ce 2007/09/13 09:34:
> My last experiment.
>
> Regards.
>
>
> ------------------------------------------------------------------------
>
Nice waxy cube.
--
Alain
-------------------------------------------------
Q: If pro is opposite of con,then what is the opposite of progress?
A: Congress!
Men's restroom, House of Representatives, Washington , DC
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote:
> My last experiment.
>
Really nice. Looks like wax to me! Best wax cube I've seen...not that I've
seen that many of 'em. ;-)
The only jarring part of the image is the red sphere; just seems out of
place (visually speaking.) Draws too much attention to itself.
Mind posting your final "wax" code? It's quite impressive.
Ken W.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
