Effect of Distance and Incidence Angle on Laser Intensity Data of Building Materials

Abstract

3D terrestrial laser scanner (TLS) provides both 3D point coordinates and intensity data of scanned object surface. The intensity data can be used to discriminate different materials, since it partly represents the object reflection characteristic at the laser wavelength. In addition to laser reflectance properties of object, the intensity data is influenced by many other factors, such as instrument mechanism, environmental condition, distance and incidence angle. In this paper, the effects of distance and incidence angle are studied. Except for standard reflector, some building facades of various kind of material were used as experimental samples. Experimental survey find that the intensity is inversely proportional to distance and incidence angle, but their relations do not agree with the theoretical model. Several models were selected to describe the relations between intensity and distance, intensity and incidence angle. The suitability of each model was analyzed by its correlation coefficient.