I have been struggling to set up lighting priperly for interior spaces.
Can't understand why it doesn't work properly :(
I use white sphere with big radius around my "room", also I use parallel
light that blows through the windows to simulate sun.
I get alot of artefacts and my "room" is totally dark :(
Could you please help me?

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motorsep nous apporta ses lumieres en ce 18/09/2006 13:54:
> I have been struggling to set up lighting priperly for interior spaces.
> Can't understand why it doesn't work properly :(
> I use white sphere with big radius around my "room", also I use parallel
> light that blows through the windows to simulate sun.
> I get alot of artefacts and my "room" is totally dark :(
> Could you please help me?
> 
> 
Do you have any other light in the scene?
If not, then you need to use radiosity. As a starter, just add "radiosity{}" in 
the global_settings{} block. Read the documentations about radiosity. The first 
element to adjust is count then error_bound.
Take a look at the various sample files in the scenes\radiosity folder, play 
around with the various parameters to get a feel of what they do.
It's obvious that any radiosity scene needs lots more calculations and therefore 
will takes longer to render.

-- 
Alain
-------------------------------------------------
WARNING: The consumption of alcohol may lead you to think people are laughing 
WITH you.

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"motorsep" <nomail@nomail> wrote:
> I have been struggling to set up lighting priperly for interior spaces.
> Can't understand why it doesn't work properly :(
> I use white sphere with big radius around my "room", also I use parallel
> light that blows through the windows to simulate sun.
> I get alot of artefacts and my "room" is totally dark :(
> Could you please help me?

One solution I have used in the past when the "dark corners" were too dark
is to place a dim point source light in the scene at the exact location of
the camera.  The shadows that are introduced by the light can't be seen by
the camera (unless there is a reflective surface) so don't show up in the
image.

I use something like this:

#declare CamLocation = <20, 20, 10>

camera {
  location CamLocation
  look_at  <0, 0, 0>
  }

light_source {
  CamLocation
  Color White*0.5
  }

Its just a hack, I know.

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Ok. This is my scene rendered in Indigo:

http://img148.imageshack.us/img148/2594/bedroom01e24hrs21minte3.png

This is the same scene, but rendered with Povray (same one parallel light
source as in above scene):

http://img153.imageshack.us/img153/8856/bedroom01fmz6.jpg

Obviously, I need to make my scene look like one that rendered with Indigo.
How can I make it look like it? What radiosity settings do I use?
Here is what I came up with:

#version unofficial MegaPov 1.21
global_settings {
noise_generator 3
assumed_gamma 2.2
max_trace_level 30
radiosity {
 pretrace_start 1
 pretrace_end 0.003125
 adaptive 2
 error_bound { 0.15 adaptive 1.5, 20 }
 count 150
 recursion_limit 1
 brightness 1.5
 }
}

Thanks.

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motorsep wrote:
> Ok. This is my scene rendered in Indigo:
> 
> http://img148.imageshack.us/img148/2594/bedroom01e24hrs21minte3.png
> 
> This is the same scene, but rendered with Povray (same one parallel light
> source as in above scene):
> 
> http://img153.imageshack.us/img153/8856/bedroom01fmz6.jpg
> 
> Obviously, I need to make my scene look like one that rendered with Indigo.
> How can I make it look like it? What radiosity settings do I use?
> Here is what I came up with:
> 
	First thing to do is to raise your recursion_limit to at least 2 (3
would be better, but be aware that this will raise the rendering
time a lot). Then, like Alain said, play with count and error_bound:
 - Higher count will give better results all around at the cost of
more computing time;
 - Lower error_bound will give sharper shadows but will slow the
render and cause the lit areas to appear blotchy (which can be
alleviated somewhat by raising the count at the cost of still more
rendering time).

	Note that you probably won't get the same graininess as the Indigo
render though :)

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
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motorsep nous apporta ses lumieres en ce 19/09/2006 00:53:
> Ok. This is my scene rendered in Indigo:
> 
> http://img148.imageshack.us/img148/2594/bedroom01e24hrs21minte3.png
> 
> This is the same scene, but rendered with Povray (same one parallel light
> source as in above scene):
> 
> http://img153.imageshack.us/img153/8856/bedroom01fmz6.jpg
> 
> Obviously, I need to make my scene look like one that rendered with Indigo.
> How can I make it look like it? What radiosity settings do I use?
> Here is what I came up with:
> 
> #version unofficial MegaPov 1.21
> global_settings {
> noise_generator 3
The default, you don't need to set.
> assumed_gamma 2.2
> max_trace_level 30
Your scene don't look as if it needs that much.
> radiosity {
>  pretrace_start 1
It's useless to start at that level. better to stick with the default here. 
Default = 0.08 or 8% of the image's width.
>  pretrace_end 0.003125
Keep it at the (pretrace_start / 2^n) domain. Other values will be rounded.
>  adaptive 2
adaptive is megapov only. Don't works with the official version.
>  error_bound { 0.15 adaptive 1.5, 20 }
Using megapov only syntax.
Defaults to 1.8. A low value requires a high count value.
>  count 150
You may need a larger value here.
>  recursion_limit 1
You need at least 2. 3 would probably be beter. 4 may not be worth it. My 
personal experience don't show that much effect on the render time.
>  brightness 1.5
To brighten up the scene.
You can add:
low_error_factor 0.4 or less.
It lowers the error_bound during the last pretrace step by that amount 
(error_bound * low_error_factor). Default to 0.5
>  }
> }
> 
> Thanks.
> 
> 
> 
> 
To get beter similarity, use a sky_sphere or large world sphere with a gradient, 
blue at the zenit and pinkish near the horizon.

-- 
Alain
-------------------------------------------------
An unbreakable toy is useful for breaking other toys.

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One thing that was not mentioned, but which concerns your POV-Ray scene in 
general: control if your finish {ambient} of the objects is set to 0, 
especially before using radiosity. I think that the pillows and the blue 
cover have an  ambient >0.

Thomas

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Thank you guys for advice.
After reviewing all answers and tuning materials and settings, I came up
with that:

http://img170.imageshack.us/img170/797/bedroom01hli4.jpg

Radiosity settings:

radiosity {
pretrace_start 1
pretrace_end 0.003125
adaptive 2
error_bound { 0.1 adaptive 1.5, 20 }
count 500
recursion_limit 3
brightness 1.5
low_error_factor 0.2
nearest_count 7
}

I use sphere around my scene with such material:

*env
pigment
{
color rgb <0.842, 0.937, 1.000>
}
finish {
ambient 2
}

And also I use parallel light.

I still can't figure out how to get a rid of artifacts (maybe to increase
count to >1000), how to have windows not being overbrightened and have room
lit more evenly and make it lighter (that are a main concerns).
Any ideas?

Alain,
If I use this formula for "pretrace_start": >Default = 0.08 or 8% of the
image's width<, I get pretrace_start = 640*0.08=51.2 and it cause a huge
increase of rendering time and I get a l ot of artifacts :( Why? What am I
doing wrong?
Also you said: "Keep it at the (pretrace_start / 2^n) domain." What is
"2^n"? I mean "n" - where is it coming from?

Thank you guys, I appreciate you time!

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Hash: SHA1

motorsep wrote:
> Thank you guys for advice.
> After reviewing all answers and tuning materials and settings, I came up
> with that:
> 
> http://img170.imageshack.us/img170/797/bedroom01hli4.jpg
> 
> Radiosity settings:
> 
> radiosity {
> pretrace_start 1
> pretrace_end 0.003125
> adaptive 2
> error_bound { 0.1 adaptive 1.5, 20 }
> count 500
> recursion_limit 3
> brightness 1.5
> low_error_factor 0.2
> nearest_count 7
> }
> 
> I use sphere around my scene with such material:
> 
> *env
> pigment
> {
> color rgb <0.842, 0.937, 1.000>
> }
> finish {
> ambient 2
> }
> 
> And also I use parallel light.
> 
> I still can't figure out how to get a rid of artifacts (maybe to increase
> count to >1000), how to have windows not being overbrightened and have room
> lit more evenly and make it lighter (that are a main concerns).
> Any ideas?
> 
> Alain,
> If I use this formula for "pretrace_start": >Default = 0.08 or 8% of the
> image's width<, I get pretrace_start = 640*0.08=51.2 and it cause a huge
> increase of rendering time and I get a l ot of artifacts :( Why? What am I
> doing wrong?

	Hem, a slight misunderstanding here: he meant that the default
value is 0.08 which will be interpreted by povray as 8% of the image
width. If you use 1 it will be interpreted as 100% of the image
width and therefore useless.

	In short, you should use "pretrace_start 0.08" as a starting point,
then see what happens when you raise or lower it slightly (ie in the
0.06-0.10 range for a start).

> Also you said: "Keep it at the (pretrace_start / 2^n) domain." What is
> "2^n"? I mean "n" - where is it coming from?
> 
	2^n means "2 to the nth power". Or in other words 2, 4, 8, 16...

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
+---------------------------------+------------------------------+
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ahh, my bad. Thank you for detailed explaination! I'll try it after work :)

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I am about to give up ;(

Here is my latet render:

http://img144.imageshack.us/img144/3954/bedroom01jbb8.jpg

Here is radiosity settings:

radiosity {
 pretrace_start 0.08
 pretrace_end 0.005
 adaptive 2
 error_bound 1.8
 count 700
 recursion_limit 3
 brightness 1.5
        low_error_factor 0.2
        nearest_count 7
 }

Here is a sphere material around my scene:

pigment {
      gradient y
      color_map {
      [0.0   color rgb <1, 0.887, 0.653>]
      [1.0   color rgb <0.313, 0.610, 1>]

   }
translate -y*.5
scale 300*4
     }
finish {
    ambient 0.5
}

I am somewhat satisfied with quality, but I got that illumination behind
closet, there is not enough contrast on the image and lighting doesn't look
realistically :( I don;t know why and I don't know what else to do :(
I need to get results as with Indigo (at least as close as possible).
Help me please :/

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> Help me please :/

You might want to look at Hildur Kolbrun Andresdottir's radiosity tutorial.
http://www.simnet.is/hildurka/content/tut1page.htm

Some important things to remember... the ambient setting in normal, non-
radiosity mode mimics ambient light, but in radiosity mode the ambient
setting in the finish of objects is the amount of light emitted. Since
most objects don't emit light, most objects in a radiosity scene should
have ambient 0. An important exception is the sky, which should emit.
The light behind the dresser looks like the ambient is not zero in some
finish near there.

Hildur's recommended settings are:

radiosity {
   brightness 2
   count 100
   error_bound 0.15
   gray_threshold 0.0
   low_error_factor 0.2
   minimum_reuse 0.015
   nearest_count 10
   recursion_limit 5
   adc_bailout 0.01
   max_sample 0.5
   media off
   normal off
   always_sample 1
   pretrace_start 0.08
   pretrace_end 0.01
}

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Thank you Tim. I will go over the tutorial and I will check my materials
once again to see if I have forgotten to put ambient value n 0.

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motorsep wrote:
> Thank you Tim. I will go over the tutorial and I will check my materials
> once again to see if I have forgotten to put ambient value n 0.
> 
	Another possible cause for the bright area behind the closet is the
'brightness' keyword. IMO, you'd be better of using a brightness of
1 and if that is too dark, use ambient (with low values of course)
to raise the overall light level. This has two advantages:
 - you can get more control over where the scene is lighted by using
different ambient values for different objects;
 - this is more physically realistic: maximum realism would be
gotten with "brightness 1", but "recursion_limit infinite". Since
that is of course not possible, a low level of ambient light will
simulate the additional recursion levels.

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
+---------------------------------+------------------------------+
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I have one question:

Do you have glass panes in the windows? I have experienced lot´s of annoying
artefacts showing up, similar to the ones you have in your latest render,
when I tried to let the light shine through glass for reflections. If you
have glass, get rid of it, it´s not worth the trouble in a situation like
this.

When rendering a dark room ike this I think it´s almost impossible to get
the outside as well. I have so far accepted that the outside will always be
overexposed, but you could try to cheat by using darker textures on the
outside.

Anyway, I´ll try to simulate your sitation and see if I can come up with
better settings.

Hildur Kolbrun

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