I am trying to use the Sun Path parameter to map the shadow cast by an adjacent building onto mine over the course of a day. I'd like to show the whole day's shadow pattern.
I can get a single hour to show clearly, but when I use multiple hours, it doesn't show, or is so faint I can't really see it.
Is there a way to adjust the settings to make it more clear? It appears each increment become fainter, so even if I have 1 hour time steps, it's hard to see. (The image for multiple hours below is half hour time steps).
DIVA is using ambient and directional lights in Rhino to create the shadow effects. When there are many time points (i.e. many directional lights), this technique necessarily produces faint shadows. You're also experiencing a surface-orientation bias. That is, shadows show up on the ground, but not on the South facing facade of the Northern building. This is also inevitable, since the low-angled suns have a greater illumination effect on vertical surfaces.
If you want to adjust the appearance, your only option is to reduce the # of time points or edit the lights by hand. To do the latter, turn on the Diva_SunPathLights layer and open the Render Tools > Lights panel. You'll probably need to turn off (or adjust the intensity of) multiple lights to isolate the facade shadows you want: