MyWork > 3D Rendering > Shadow Volumes

Overview

Shadow volumes are a popular way to generate sophisticated shadows in real time. I have applied shadow volumes in an application for calculating shadow profiles in real time. A shadow profile shows the cast shadow of an object over a specific time period. This is, for example, of concern for architects to find out how long the surroundings are obscured by a building. After providing the required information needed for computing the position of the sun (latitude, date, time) and the time period, the shadow profile can be calculated.

Examples

left: Shadow of the Eiffel Tower in Paris (latitude of 48.8° north) on September 18th at 2pm.
middle: Visualization of the shadow volume (yellow) and the silhouette edges (pink).
right: Shadow profile over a time period of four hours (10am until 2pm in 30 minutes intervals).

left: A building in Sweden at a latidude of 62° north on June 14th at 1pm.
middle: Visualization of the shadow volume and silhouette edges.
right: Shadow profile over a time period of 8 hours, starting at 9am in 15 minutes intervals. Darker areas mean longer in shadow.

left: Shadow of Vladmir Tatlin's Tower - a monumental building which should be build in Petrograd (St. Petersburg) after the October Revolution - on the 8th February at 12:20pm at a latitude of 59° north.
middle: Visualization of the shadow volume (yellow).
right: Shadow profile over a time period of 5 hours (10am until 3pm) in 10 minutes intervals. The scene consists of 125232 triangles.

Further information

I have written two papers about this. Geometry of Real Time Shadows and Schatten in Echtzeit. The latter is a general overview paper in German. For those who want a more detailed treatment of the topic I recommend reading the former.