"Anthony D. Baye" <Sha### [at] spamnomorehotmailcom> wrote:

> and thanks for the tips on HDRI.  Now I just need a step-by-step tutorial on how
> to use it in scene.

There's not much to it really:

1) To create an HDR image for use as IBL just render your scene with a spherical
camera; here's the default from the Insert menu:

camera {
  spherical
  location <0,0,0>      // position
  look_at  <0,0,1>      // view
  angle 360             // horizontal degrees
        180             // vertical degrees
}

Render the scene using command-line (for example) +fe +w2048 +h1024 to produce
an EXR image.

2) Then you can use this resulting EXR image as the IBL for any scene by
wrapping it on a huge sphere to act as the environment lighting, something like
(assuming radiosity):

sphere { 0, 10000 hollow inverse
   pigment { image_map { exr "SomeEXR" interpolate 3 map_type 1 }}
   finish { emission 2 diffuse 0 }
}

If there are any unwanted speckle-artifacts from the EXR lighting in a scene
(likely due to sampling errors over very large differences in neighboring pixel
colors) I make a smaller, heavily blurred version of the EXR in GIMP or PS and
use that instead, say 512x256 pixels.

-------------------------------------------------
www.McGregorFineArt.com

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