Twilight Render User Forum

Changing the radius of your light source is important (for Sun, see post below)

:>: Download the test scenes here.

The radius determines the softness of the edges of your shadows. The softness of the shadow can have a major impact on the realistic look of your images, but also it can have a major impact on render times. In general, the smaller the radius, the faster the render times. Fortunately, it also looks more realistic, up to a certain point.

Watch this animated .gif to see an in depth exploration of Spot and Point Light Radius Settings.
Watch what happens when the radius of the light is greater than the space within which the light is placed.
The space is only 48 inches wide, with the light source placed 6 inches below the ceiling. This means that if the radius of the light source is greater than 6 it will effect negatively the lighting effect. This is especially noticeable in the images below when the radius is greater than 16.

Soft Shadow Radius Setting Comparison Sheet for the Twilight Render Sun and Sky:
Notice that even with radius as low as 20, the shadow is quite soft. Radius of 10 for sun is ideal for full-daylight situations with exterior renderings, and less than 20 for interiors.

Here you can download the 2 .skp files and test them for yourself. (they will open with SU7 or SU8)

THANKS fletch

Very cool post. Quite helpful. I didn't really understand the relationship of those light functions, till now.

thanks!