Can I use a light for diffuse or specular lighting only?

In various cases, it might become handy to have lights that produce highlights only, or just no highlights at all. This can be done easily, but requires the use of the Advanced interface to the Material Room. The options described below are not available through the Simple interface.


When I open the properties of a Light in Material Room, I see

  • A generic Color and Intensity
  • A Diffuse (color swatch)
  • A Specular (color swatch)

The generic Color and Intensity are multiplied to one result as any regular Color/Value pair in the material definitions, and used in preview. The two latter ones are used in the Poser render only, multiplied by the generic Color and Intensity. So:

  • When I black out the Diffuse, I’ll have a Specular only light in my render.
  • When I black out the Specular, I’ll have a Diffuse light only in my render
  • When I black out both, I’ll have no light in my render, but still one in preview.

The first is a necessity in IBL or IDL lit scenes, as these do not produce any specularity themselves (but diffuse light only). Usually, I don’t need the extra diffuse part.

The latter is a handy tool in scenes with IDL lighting only. This lighting does not show in preview, so for building the scene I need some lights which won’t show at render time.

How the aspects work together:

when the Diffuse is 80% Green, Specular is 60% Blue, Color is 40% Grey and Intensity is 50% than

  • When rendering, the light produces a 50% (Intensity) x 40% (Grey) x 80% (=16%) Green diffuse light, plus a 50% (Intensity) x 40% (Grey) x 60% (=12%) Blue specular light
  • When previewing, the light produces a 50% (Intensity) x 40% (=20%, Grey) light


  • IBL Lights are supposed to have an image map attached, and do NOT produce any specular lighting despite my settings. IBL lights do show in preview.
  • Under IDL (InDirect Lighting) rendering conditions, all objects in the scene behave as a light, but diffuse only. IDL lighting does not show in preview.

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