Setup

Video Range Measuring

Overview

The video range modules in PAMGuard are used to analyse grabbed video images in order to measure the range to an object floating on the water.

The principle of the method is very simple. The range to floating objects at sea can be calculated from the angle of dip between the horizon and the waterline of the object. Often this angle is estimated using reticules in binoculars, but this is difficult and inaccurate, especially when the subjects are small marine mammals that are only fleetingly visible at the surface. However, the angle can be measured accurately and at leisure from an image taken with a calibrated lens from a known height.

images can be obtained using either still or video cameras. With the advent of affordable higher definition video equipment HD camcorders are usually the most effective means of obtaining the necessary images. Some practical information on equipment and field procedures can be found at http://www.ecologicuk.co.uk/

The method can also be applied from land stations (an application for which theodolites are traditionally employed.) When used from land station its necessary to configure PAMGuard with a fixed stationary array. Instruction on setting up PAMGuard in this mode are found here.

The methods implemented here are described in detail in Leaper, R., and Gordon, J. 2001. Application of photogrammetric methods for locating and tracking cetacean movements at sea. J. CETACEAN RES. MANAGE. 3(2):131�141

The first step is to create an instance of a video range module in PAMGuard

Next: Adding and Setting up a New Video Range Module