Color lookup tables and ambient lighting

[Ron Inbar]

John,

The Ambient property isn't a binary toggle.  It's a continuous variable
which takes any value between 0 and 1.  Try to set it to 0.2, for example.

The overall color of a pixel is a linear combination of its ambient, diffuse
and specular colors.  The Ambient property is simply the coefficient of the
ambient component in this combination.  If you set it to 1 (the maximum), it
may cause the ambient component to make the R, G, and B of the overall color
greater than 1.  In this case they are clamped to 1 and you are left with
uniform white.

Ron

----- Original Message -----
From: <jnorris at uiuc.edu>; <jnorris at uiuc.edu>
To: Vtk Mailing List <vtkusers at gsao.med.ge.com>
Sent: Friday, October 01, 1999 00:19
Subject: Color lookup tables and ambient lighting


> Hello all,
>
> I'm using a recent nightly release of VTK 2.4.  I'm rendering an actor
using
> a lookup table in the mapper.  I want to increase the ambient lighting so
> that the shadows aren't as dark, but apparently the lookup table isn't
> consulted when it comes to ambient properties.  For instance, if I
SetAmbient
> to 1 in the actor properties, I'd expect the actor to have bright colors
and
> no shadows.  Instead, the actor becomes solid white.  Is this the desired
> behaviour?  Am I missing a setting somewhere that causes the renderer to
use
> the lookup table when using ambient light?
>
> Thanks,
> John
> --
> John Norris
> Center for Simulation of Advanced Rockets
> jnorris at uiuc.edu
> http://www.uiuc.edu/ph/www/jnorris
>
>
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