What is the perpendicular distance calculator?
The Perpendicular Distance Calculator is a platform-independent Java application that implements a powerful suite of spherical functions for processing observations made during standard line transect surveys. Line transect sampling a commonly used distance sampling method that can be used for estimating the density and/or abundance of biological populations.

Why use spherical functions?
The Perpendicular Distance Calculator implements methods founded in spherical geometry because calculations can be performed directly with geographic coordinates (i.e., latitude and longitude) and standard compass bearings.

What are the hardware requirements?
Since the Perpendicular Distance Calculator is written in Java, it will run on any operating system (Microsoft Windows, Mac OS, Unix, Linux) that has a Java Runtime Environment (JRE) installed. You can get the latest JRE from Sun Microsystems at

How much does it cost?
Absolutely nothing! The Perpendicular Distance Calculator is an open source initiative and distributed free of charge with no warranty as stipulated in the GNU General Public License . the application can be obtained from the download page.