Advanced processing capabilities with imaging laser altimeter ScaLARS

Abstract

The Institute of Navigation/University Stuttgart has developed an airborne Scanning Laser Altitude and Reflectance Sensor. This paper describes an approach to automatically detect and extract artificial surface objects using the data of imaging laser altimeters. Laser altimeters register surface topography directly in three spatial dimensions by measuring the distance to individual surface points. Beyond mere ranging advanced imaging laser altimeters like the Scanning Laser Altitude and Reflectance Sensor (ScaLARS) are also able to actively measure surface reflectance. By fusing both the 3-D geometry and surface reflectance, object detection and identification can be done automatically. In a first step, surface objects are detected by applying a morphology-based filter to the elevation data. In order to detect also large buildings which tend to make morphological filtering fail an additional approach based on a progressive local histogram analysis of elevation is used. The detected surface objects are then separated into artificial objects (buildings) and natural objects (vegetation) in the second step, using surface reflectance data, and/or elevation 'texture' and surface orientation. To demonstrate the effectiveness of these identification criteria, they are applied to a test data set collected with the ScaLARS laser altimeter.