MEASUREMENT OF PHYSICAL SURROUNDINGS OF RIVER WITH A HELICOPTER-MOUNTED 3D LASER SCANNER SYSTEM OF HIGH PRECISION

Abstract

A 3D laser scanner system of high precision installed on a helicopter is applied to measure the physical environment of Ohta River that has different land covers. At the same time VRS-RTK-GPS surveying and measurement of vegetation height and bed material size are carried out to check the accuracy of the data. First, the laser scanner system is confirmed to yield accurate DSM as far as the data obtained at 300m and 600m altitude are concerned. Second, a filtering method is proposed that considers the characteristics of land covers such as water, vegetation, gravel and the others and is found to be effective to obtain reliable DEM. Third, it is shown that the longitudinal profile of water level is well estimated by detecting the land-water border. Last, the average size of river bed materials is also reasonably estimated by using the standard deviation of ground level in a mesh of 2m × 2m.