D3PLOT 22.1

Ambient Light The %age Of "Black Body" Light

Ambient light The %age of "black body" light

If only point light sources are used this simple lighting model produces images reminiscient of pictures from space: strongly directional lighting with no detail in shadow areas. Therefore the concept of Ambient light, analagous to "black-body" radiation coming from the universe at large, is added to fill on lowlight areas.

This is not realistic in itself, but in practice most scenes have their shadow and low-light areas filled in by reflected light from walls, floors, etc; and it provides a good approximation to this.

This image has a single directional light to the right, and has the Ambient light set to 0%.

Note how the lowlight areas are extremely dark and contain no detail.

Here is the same image with the Ambient light set to 40%.

This has filled in the lowlight areas to some degree, but a higher value still is needed to illuminate some areas.

Why bother with ambient light? Why not just use more (and more realistic) point light sources?

The short answer is speed and simplicity. Ambient light is cheap to compute and easy to define, whereas adding point lights slows down image redraw speed. And, as any photographer will testify, getting the position and intensity of multiple light sources correct is not as simple as it seems. However you have 8 light sources to experiment with: feel free! (But note that some graphics hardware may not operate correctly, or may run slowly, with more than two light sources.)

The default in D3PLOT is a single directional light above and to the right of the observer's position, and an Ambient light level of 40%.

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