ASSESSMENT OF SENSOR CHARACTERISTICS OF AN AIRBORNE LASER SCANNER USING GEOMETRIC REFERENCE TARGETS

In order to get an experimental insight on the characteristics of a modern airborne laser scanning system, we carry out a set of experiments using geometrical targets on an air strip and use different flying heights. Sensor noise and relative accuracy is evaluated through 4 cardboard tables, being plain and homogeneously reflecting. The standard deviation of all laser returns from such a target decreases with lower flying altitude, as well as positional offsets computed tend to increase with flying altitude. The positional error along track is smaller than across track, probably due to different point spacing in these two directions. Target size and reflectance effects are assessed using wooden slats of different widths and colors. The effect of reflectance on target visibility is much larger than the effect of target size, which is in agreement to theoretical findings. Effective footprint size is attempted to be determined by slats with high reflectance forming a star. The difference between geometric (computed only by beam divergence) and effective footprint size increases with measurement distance, with the effective diameter being smaller than the geometric one.