POV-Ray : Newsgroups : povray.general : Shadows and lighting with HDR sky : Re: Shadows and lighting with HDR sky Server Time
18 Oct 2021 16:41:31 EDT (-0400)
  Re: Shadows and lighting with HDR sky  
From: Kenneth
Date: 29 Sep 2021 01:25:00
Message: <web.6153f546c55e1a844cef624e6e066e29@news.povray.org>
"borix" <nomail@nomail> wrote:
> There isn't much more shadow even with error_bound 0.01. What it does is
> that it changes the pattern on the left side of the cube.
>
> The sun is near the horizon in the hdri.

To add to what Alain said: With a few 'higher quality' radiosity settings, I do
see a shadow. I think each person has his or her own set of 'favorite'
settings-- mine change on a weekly basis, ha.

My own *basic* rule-of-thumb is to use very small settings for
minimum_reuse ...
maximum_reuse ...

This creates smaller light 'patches', which more accurately get into and around
corners, etc. (But then other rad values need to be tuned as well, including a
higher count to get ride of that splotchy 'pattern' you mentioned. All of which
naturally makes for a slower render...)

I was actually surprised that I *do* see a shadow; the particular HDR image that
you used has a somewhat uniform sky color/brightness, with the
Sun below the horizon. Also, the 'dark' result on the plane is probably a
natural result of the relatively dark sky in most of that image.

----- example -----
#version 3.8; // or whatever

global_settings {
assumed_gamma 1
    radiosity {
      pretrace_end 0.001
      count 1100
      recursion_limit 1

      // [I added these three...]
      minimum_reuse .0032
      maximum_reuse .0032*5
      always_sample on // off by default. I prefer this ON

      low_error_factor 0.2
      brightness 1
   }
}

camera {
  perspective
  location  <10, 11, -20>
  look_at   <10, 4,  0>
  right     x*image_width/image_height
  angle 67
}


sky_sphere{
    pigment{
        image_map{ hdr "lilienstein_4k.hdr"
        map_type 1 interpolate 2}
           }
}

box {
    <0,0,0>, <8,8,8>
    pigment {rgb <239, 204, 148>/255}
    rotate 35*y

}

plane {
    y, 0
    pigment { rgb 1}
}


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