Application of terrestrial lidar for biological monitoring

Abstract

In this paper, the terrestrial LIDAR method was utilised to conduct two biological monitoring studieson fauna and flora monitoring. In the first study, we utilised terrestrial LIDAR to conduct a populationcount of roosting bats where prior methodologies in censuring roosting bats involves direct roostcount for single individuals or small clusters while larger clusters are estimated by multiplying of thesmaller clusters. Visual counting methods includes emergence counts, dispersal counts anddisturbance counts during daylight or crepuscular conditions, often with an optical-mechanicalmethods for species confirmation such as acoustic bat detector, infrared cameras, thermal images andradar systems. Using LIDAR, we generated millions of high resolution “point clouds” that created a3D image of the bats and the cave thus producing a high resolution image of each bat without directcontact. We can spatially analyse the three dimensional distribution of bats populations as well asgenerate a 3D topological structure of the cave that the bats dwell in, thus providing a high resolutionmodel of the cave and an accurate count of the bats and their roosting pattern. In the second study, weused terrestrial LIDAR to rapidly and remotely determine the diameter at breast height (DBH) of rubber trees. Conventional measuring method is time consuming and labour intensive as the DBH hasto be measured by going to every single tree. The LIDAR scanned effectively measured the DBH of the trees in the scanning path, enabling high resolution measurements (2 mm), location and thetopology of the landscape be captured for data analysis. The laser point clouds density was sufficientto extract information and the scanner easily deployable in the field. Repeated scans will allowtemporal comparison of the growth of the rubber trees by overlapping the point clouds data. We haveshown that terrestrial LIDAR is able to provide a novel methodology in biological studies and itsdeployability, accuracy and speed would make it a useful research tool in the future.