An automated GIS procedure for comparing GPS and proximal LIDAR elevations

High-resolution elevation surveys utilizing light detection and ranging (LIDAR) are becoming available to the geoscience community to derive high-resolution DEMs that are used in a variety of application areas. However, prior to the application of these data to geomorphic interpretation, extensive validation procedures should be employed. The vertical accuracy specification for the survey called for heights to be within an average of 15 cm of measured GPS heights and 95% of the data to be within 30 cm. Two different LIDAR systems and collection methods were employed to collect data for the study area located in the Mesozoic Fundy Basin in eastern Canada. High-precision GPS surveys were conducted to measure the ground elevations in open areas and a traditional topographic survey was carried out in order to assess the accuracy of the laser data under the forest canopy. The LIDAR and validation data were integrated into a GIS where an automated procedure was developed that allows the user to specify a search radius out from the validation points in order to compare proximal LIDAR points. This procedure facilitates examining the LIDAR points and the validation data to determine if there are any systematic biases between flight lines in the LIDAR data. The results of the validation analysis of the two LIDAR methods and a description of the automated procedure are presented in this paper.