clipka <ano### [at] anonymousorg> wrote:
> Am 15.03.2017 um 16:40 schrieb muyu:
>
> > Now I am able to simulate the reflectance of 3D canopy using Pov-ray. However it
> > seems a little bit underestimate compared with Monte Carlo approach (the
> > reference dataset). I am wondering if physically radiosity based apprroach in
> > Pov-ray ignore some processes. If not, how can I improve the accuracy of this
> > estimation? Thanks in advance again.
>
> and (in povray.beta-test):
>
> > Thanks. I tested the back side illumination with radiosity. I am rendering a
> > scene with very dense leaves. The objective is to get the physically accurate
> > illuminace of each pixel. I set the assumed_gamma and file_gamma as 1.0. Then
> > this the pixel color is supposed proportional to the illuminace? However, it
> > seems the light does not propagate deep enough into the canopy (with radiosity
> > and side diffused light). When compared with the reference results achieved with
> > Monte Carlo method, the illuminace or reflectance is underestimated. I am
> > wondering this is because Pov-ray ignore some physical processes or I did not
> > set the right functions. Thanks again.
>
> You may need to significantly increase the radiosity `recursion_limit`
> setting.

Thanks for your suggestions.

I am using the following code:

#version 3.7;

global_settings {
   assumed_gamma 1.0
   ambient_light 0.0
   max_trace_level 100
   adc_bailout 0.0

   radiosity {
      count 1500
      gray_threshold 0.00
      error_bound 0.05
      brightness 1.0
      normal on
      recursion_limit 20
   }
}

//-----------------------------------------------------------------------------
light_source{<0,363.97,1000> color rgb<0,1,0> parallel}

The recursion_limit has been set as the maximum. But it still a little bit
underestimate.

1) Do you have other suggestions to increase the accuracy?

2) gray_threshold has to be set as 0.0? I found that this impacts significantly
the result.

3) brightness seems has no significant on the result. Is it correct to set
brightness as 1.0?

Thanks in advance.

Post a reply to this message