Measurement of cylindrical objects through laser telemetry: application to a new forest caliper

The feasibility of a new method for robust radius determination of cylindrical objects is studied. The principle is based on laser telemetry under structured lighting, where a laser plane creates a line on the object under test, which is observed by a charge coupled device camera. The novelty is in what we call the "three-tangents method" for the radius calculation. We show that this method is the most reliable one, taking into account the particular curve\´s characteristics. We mainly applied it to tree measurements in forests, for which a pre-prototype caliper was built. Experimental results are given. A general accuracy of 1% on 10-50-cm diameter trunks is claimed for distances up to 3.5 m.