Vertical accuracy and calibration of digital elevation models (DEMs) for the piranhas-assu river Basin, Rio Grande Do Norte, Brazil

Abstract

There is a growing need for high resolution altimetry data to use in environmental research in the last years. Therefore, addition criteria must be applied for this data usage, especially due to vertical error. This paper focuses on vertical error evaluation and calibration methodology of Digital Elevation Models (DEM) obtained with Shuttle Radar Topographic Mission and with airborne Light Detection and Ranging in the Piranhas-Açu river basin; north part of Rio Grande do Norte State, Brazil. The evaluation and calibration was conducted in two sectors of the study area: regional and local. The regional sector was evaluated with SRTM data only and the local sector with DEM from SRTM and airborne LiDAR. The calibration used a network of high vertical accuracy altimetric control points data. The results show that the in the study area the SRTM DEM accuracy is satisfactory and was improved by 26-29% after calibration. In the local area, airborne LiDAR is more accurate than SRTM and was also enhanced by control points calibration (15%). This paper demonstrates the need for vertical error analysis and calibration in DEM prior to topographic use.