Noise free rendering of simple sun/sky scene

radiance-general
1

Dear all,

I am new to this list .. and not all that experienced in using Radiance.

I have problems determining render parameter settings that will produce an (almost) noise free rendering of simple scenes illuminated by a sky dome and a sun disk. I want to have soft shadows from both the sky dome (180 degree source) and the Sun (0.53 degree source). My .rad file is listed below. I realize that both sources (sky and sun) are "white" ... thats not the issue ... I am just sending the simplest form of the types of scenes I wish to render.

I am rendering with these parameters, but the results are horrobly noisy, and I do not get soft shadows from the Sun:
rpict -x 640 -y 480 -ab 2 -aw 0 -dr 3 -dp 4096 -ds 0.01 -dj 0.6

I have the Rendering with Radiance book, but cannot really find a clear "how to" in terms of setting the parameters so that my picture comes out right.

Hope I am not offending anybody by posting such a simple problem.

Sincerely,
Claus

P.S. I am performing research in Augmented Reality and will be using my renderings in conjunction with techniques I have developed for estimating the Sun and the Sky radiances from images of real scenes. I will the render some simple geometry using Radiance and compose into the image with correct shading and shadows

···

------------------------------------------------------------------------------------------------------------
# Materials

void plastic white_matte
0
5 1.0 1.0 1.0 0 0

# Objects

white_matte sphere ball4
0
4 0.0 0.0 2.0 2.0

!genbox white_matte groundplane \
20 20 0.5 -r 0.08 | xform -t -10 -10 -0.25

# Illumination environment: a 0.53 degree diameter disk and a
# 180 degree skydome

# The Sun ... radiance set to provide unity irradiance for
# normal pointing right into the sun
void light sunradiance
0
3 14880 14880 14880

sunradiance source TheSun
0
4 -1 -1 1 0.53

# The Sky ... radiance set to provide unity irradiance for
# normal pointing right into the sky
void light skyradiance
0
3 0.159 0.159 0.159

skyradiance source TheSky
0
4 0 0 1 180.0
------------------------------------------------------------------------------------------------------

2

Hi Claus,

without having seen the results - usually such artefacts result from weak ar, ad, as settings. We also do not know the scene. Can you provide us both with a sketch (e.g. wireframe screenshot or hand drawing) and an image showing the noise, both low res and/or an a website? Usually you can improve the visual quality by either setting higher values for the ambient parameters or using workarounds as mkillum.

One other hint. Create a rif file and render using rad. That will help a lot at the beginning, as rad will set some parameters for your scene (and you can display those).

Good luck! CU Lars.

3

Hi Claus,

I suspect that the noise you are seeing is a results of the -dj parameter. There are a couple of things to note here:

   1. oversample the image - eg render at higher resolution (3x to 6x
      desired final resolution) and then downsample with: pfilt -r .6 -x
      /3 -y /3 oversample.pic > final.pic (this would reduce the image
      size 3x and apply a gaussian filter)
   2. reduce -dj setting - this will produce less sampling jitter, but I
      am not sure what your objective is here
   3. pseudo random monte carlo vs. random monte carlo sampling - when
      run with normal parameter settings radiance (rpict) uses pseudo
      random sampling, with this you may notice directionality or
      striation effects in the jittered samples, alternatively radiance
      can be run with uncorrelated sampling by using the -u switch, this
      will get rid of the directional effects but may require even
      greater oversampling to reduce sampling noise due to the random
      sampling

Hopefully this helps, I expect that you may get other input from the list as well.

Regards,

-Jack de Valpine

Claus B. Madsen wrote:

···

Dear all,

I am new to this list .. and not all that experienced in using Radiance.

I have problems determining render parameter settings that will produce an (almost) noise free rendering of simple scenes illuminated by a sky dome and a sun disk. I want to have soft shadows from both the sky dome (180 degree source) and the Sun (0.53 degree source). My .rad file is listed below. I realize that both sources (sky and sun) are "white" ... thats not the issue ... I am just sending the simplest form of the types of scenes I wish to render.

I am rendering with these parameters, but the results are horrobly noisy, and I do not get soft shadows from the Sun:
rpict -x 640 -y 480 -ab 2 -aw 0 -dr 3 -dp 4096 -ds 0.01 -dj 0.6

I have the Rendering with Radiance book, but cannot really find a clear "how to" in terms of setting the parameters so that my picture comes out right.

Hope I am not offending anybody by posting such a simple problem.

Sincerely,
Claus

P.S. I am performing research in Augmented Reality and will be using my renderings in conjunction with techniques I have developed for estimating the Sun and the Sky radiances from images of real scenes. I will the render some simple geometry using Radiance and compose into the image with correct shading and shadows

------------------------------------------------------------------------------------------------------------

# Materials

void plastic white_matte
0
5 1.0 1.0 1.0 0 0

# Objects

white_matte sphere ball4
0
4 0.0 0.0 2.0 2.0

!genbox white_matte groundplane \
20 20 0.5 -r 0.08 | xform -t -10 -10 -0.25

# Illumination environment: a 0.53 degree diameter disk and a
# 180 degree skydome

# The Sun ... radiance set to provide unity irradiance for
# normal pointing right into the sun
void light sunradiance
0
3 14880 14880 14880

sunradiance source TheSun
0
4 -1 -1 1 0.53

# The Sky ... radiance set to provide unity irradiance for
# normal pointing right into the sky
void light skyradiance
0
3 0.159 0.159 0.159

skyradiance source TheSky
0
4 0 0 1 180.0
------------------------------------------------------------------------------------------------------

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# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

4

... using the '-e' and '-n' options of rad.

Then use 'rpict -defaults' to see what rpict has used instead
(apart from the few options you specified in the command line).

Figure out what each of the options does to your scene/image
and you should be able to gradually improve your result.

It may take you a while, though.

Thomas

···

On 8 Nov 2007, at 15:17, Lars O. Grobe wrote:

One other hint. Create a rif file and render using rad.
That will help a lot at the beginning, as rad will set
some parameters for your scene (and you can display those).