Move the pointer at the Direction panel to change the position of the light source, which is located on a virtual sphere around the texture. This means that you can increase the height of the light source by decreasing the radius of the direction pointer.

The Heightmap controls where the texture is illuminated and where not. Places in the shadows don't receive light. It is supplied by the Source Texture or the Mask.

Regulate the intensity of the light source with the Amplify value.

Control the smoothing of the edges between the illuminated and the shadows with the Smooth Radius parameter. Setting the value to 1 produces hard edges.

The illumination is done by using the Secondary Color as basic (ambient) light, which is constant over the texture. The Primary Color defines the tint of the light source.