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This are the pics from my new kitchen. The first row with radiosity on, the
second with radiosity off.
During rotating the camera there is change of brightness when radiosity is
on.
Except of camera there is no change in the scene.
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gabriel wrote:
> During rotating the camera there is change of brightness when radiosity is
> on.
> Except of camera there is no change in the scene.
Do you collect radiositiy data at every shot? If not, this might be the
answer...
Just my two eurocents,
Bonsai
--
<--------------------------->
___ __ __ _ ___ ___ _
| _ ) \ \( ) _) _ )( )
| _ \() |\ \ |\ \/ _ \| |
|___/__/_)\__)___)/ \_)_)
www.b0n541.net
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Yes, that is what will happen. This is why distributed processing is such a
pain with radiosity: samples are collected from those pixels IN the image,
not off of it. My IRTC 'Museum' entry was distributed, so the light in the
top half is not quite the same as that in the bottom half. There may be a
way to pre-render samples from a fisheye image, and apply that to a
sectional image, but if there is, I do not know what it is. This also makes
light composition difficult in many cases- if a window is not bright
enough, you cannot plce it behind the camera and expect to get radiosity
from it.
-s
5TF!
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"gabriel" <gna### [at] web de> wrote:
> This are the pics from my new kitchen. The first row with radiosity on, the
> second with radiosity off.
> During rotating the camera there is change of brightness when radiosity is
> on.
> Except of camera there is no change in the scene.
What are your radiosity settings?
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> if a window is not bright
> enough, you cannot plce it behind the camera and expect to get radiosity
> from it.
This statement clearly indicates that you're not aware of how radiosity
actually works. It has nothing to do with the brightness of an object. It's
the size.
Samples are taken during the rendering to ensure that the *image you see* is
properly lit. With some precalculated distribution function, rays are sent
into the scene to check for lighting conditions. The amount of rays traced
this way depends on "count". The level of rebounces, quite obviously, is set
with recursion_limit.
Nontheless, only the visible area is sampled. Additionally, the sampling may
(and most probably will) miss small objects on some occasions, while hitting
them on others. Simple scenes with lots of large objects thus usually
require a smaller count than complicated scenes with small objects scattered
around in a large volume.
So, if you look at one wall, that wall is properly lit using radiosity. But
there are no samples on the other walls. If you'd simply turn the camera
around without taking additional samples, you'd see lots of dark spots, as
there are no samples whatsoever (depending to a degree upon
recursion_limit).
To ensure a more consistent lighting, you can simply render several views of
the scene and save the individual radiosity data using "save_file". AFAIK,
you can then copy-paste the content of these files into one big file and,
when rendering a final pass for the image or even animation, use load_file
to load that file (remembering to set "always_sample" to off). Unless you
have too few samples, POV-Ray won't add new ones, and the lighting should
stay pretty consistent. I haven't tried and tested this however, but it's
what some said in regard to this on earlier occasions.
As for the original post: the above described technique is whats changing
the brightness. Depending on the placing of the samples, they may yield
different results, depending on if they hit bright objects, or not. I
imagine the relation between viewing angle and sampling in regard to surface
normal is also a factor, but I'm not sure about that part. Nontheless, a
slightly different setting of the scene returns different radiosity sampling
and thus, different lighting conditions.
Regards,
Tim
--
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
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"nomail" <nomail@nomail> wrote:
> What are your radiosity settings?
Here the parts of scene:
#version 3.6;
#declare Radiosity=on;
#declare Lamps=off;
#include "kitchen_tex.inc"
global_settings {
assumed_gamma 1.0
#if (Radiosity)
radiosity {
pretrace_start 0.1
pretrace_end 0.01
count 10
nearest_count 5
error_bound 1.8
recursion_limit 3
low_error_factor .5
gray_threshold 1.0
minimum_reuse 0.01
brightness 2.5
adc_bailout 0.01/2
always_sample off
max_sample 1.0
}
#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
}
}
....
#declare Kamera = camera {
right x*image_width/image_height
location <0,0,0>
angle 90
look_at <1,-0.1,0>
rotate ( A0+PicNum*da)*y
translate <PX,PY,PZ>
}
....
sky_sphere {
pigment {
gradient y
color_map {
[0.0 rgb <0.0,0.2,0.5>]
[0.7 rgb <1,1,1>]
}
}
}
#declare Sun = light_source {
<100,50,10>
color rgb 1
// light_source { ...
// put this inside a light_source to make it parallel
parallel
point_at <0, 1, 0>
}
....
#include "kitchen_obj.inc"
// light_source { Licht }
Sun
union {
object { draussen }
object { parkett }
object { Boden }
object { Decke }
object { Wand }
object { Tueren }
object { Fenster }
object { Fliesenband }
object { Unterschraenke }
object { Oberschraenke }
object { Bodenblende }
object { Arbeitsplatte }
object { Tisch }
object { Spuele }
object { Eherd }
object { Lampe1 }
object { Lampe2 }
}
camera { Kamera }
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gabriel wrote:
> global_settings {
> assumed_gamma 1.0
> #if (Radiosity)
> radiosity {
> ...
> always_sample off
> ...
> }
> #end
> }
That's what I thought yesterday. You switched radiosity sampling off.
Tim gave a good explanation above on how to avoid it...
So long,
Bonsai
--
<--------------------------->
___ __ __ _ ___ ___ _
| _ ) \ \( ) _) _ )( )
| _ \() |\ \ |\ \/ _ \| |
|___/__/_)\__)___)/ \_)_)
www.b0n541.net
<--------------------------->
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> That's what I thought yesterday. You switched radiosity sampling off.
In the final pass only, always_sample only switches sampling off for the
final pass, which means that some areas might get too little attention if
the prepasses didn't cover them thoroughly.
Regards,
Tim
--
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
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> count 10
> nearest_count 5
> error_bound 1.8
These values alone could cause quite some problems this way. To sample the
lighting, you only shoot 10 rays into the scene per radiosity sample. You'll
miss large sections of the scene that way, and get very imprecise sampling
results.
error_bound is set too high, so it's quite possible that when averaging
neighbours of samples (nearest_count will search for 5 radiosity samples in
close proximity and average the results for a smoother lighting), you take
some of the very bright ones inside the door into account somewhere.
Additionally, the sampling with only 10 rays could be the source for the
bright scenes inbetween, when more of these rays hit the bright door instead
of some other area.
Finally, all you're objects seem to be glowing if you use ambient 0.1 on all
objects for the radiosity. You should only have lightsources (which, in the
case of radiosity, doesn't have to be the literal light_source, but may be a
large object with a high ambient value) with high ambience values. The
sky_sphere also works like a lightsource, which is something to keep in mind
for outdoor-scenes.
Regards,
Tim
--
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
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