Photogrammetric Point Cloud Analysis of Desert Fringe Shrubs’ Shape

Shrubs are dominant life forms in arid and semi-arid climatic regions. Shrubs are carbon dioxide sinks; they prevent soil erosion and contribute to the water balance. However, there is limited information regarding the structure and biomass of these shrubs and their change across climatic gradients, partly due to limitations on the use of destructive methods. This work concentrates on the study of the shrubs` shape, and their volume which allows estimates of biomass. A field survey of 28 shrubs and dwarf shrubs was conducted at three sites ranging from sub-humid to arid climate areas in central Israel. Photogrammetric point clouds were generated from smart phone pictures for each shrub using PIX4D software. A comparison of the estimated volume of point clouds and the volume of 3 models: semi-ellipsoid, spherical cap, and cylinder was conducted. Using fine alignment between shrubs’ point clouds and the three model shapes, it was found that semi-ellipsoid is more suitable to describe the shape of most of the shrubs photographed.