Area of Convergence and Area of Origin Determination:

The common area of convergence can be determined based upon the geometric appearance of the bloodstains within a blood spatter pattern

The line drawn through the long axis of each individual bloodstain can then be extended back to common area of convergence.

By calculating the angle of impact each individual bloodstain, a 3-dimensional area of origin can then be determined mathematically or physically using strings.

A software program such as BackTrack or HemoSpat can also be used to determined the area of origin(s)
of the blood spatter.