Abstract:

This study presents two enhancing fusing techniques for positional accuracy for Digital Elevation Models (DEMs). By utilizing the free access available DEMs, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) with a spatial resolution of 30 meters and vertical accuracy of ±16 meters, and the Shuttle Radar Topography Mission (SRTM) with a spatial resolution of 30 meters and vertical accuracy of ±20 meters. The ASTER and SRTM DEMs have been collected for an area with a varying terrain of 8.9 km² located in the south of Bahrain to practice the fusing techniques. The national DEM of Bahrain for the selected location has a spatial resolution of 50 meters and vertical accuracy of ±5 centimeters. By utilizing the DEMs collected, the DEMs fused are gridded by applying the multiquadric radial basis function (MQ-RBF) and the Triangulation Irregular Networks with Linear Interpolation (TIN with Linear Interpolation). Two fusing techniques proposed and assessed in this study, the direct fusing technique (Paradigm 1), produced two sensor-fused DEMs with an absolute error of - 3.59 centimeters and - 4.61centimeters for TIN with linear interpolation and MQ-RBF, respectively. The statistical method (Paradigm 2), produced two sensor-fused DEMs with an absolute error of - 9.47 centimeters and - 9.54 centimeters for TIN with linear interpolation and MQ-RBF, respectively, with respect to the benchmark provided by the Survey Land and Registration Bureau of Bahrain (SLRB). Four sensor-fused DEMs were generated with acceptable quality according to the absolute error values. Comparing the sensor-fused DEMs to the national DEM of Bahrain, the spatial resolution has been enhanced from 50 meters to 5 meters with the vertical accuracy of - 3.59 centimeters with respect to the ±5 centimeters vertical accuracy as per claims of the data provider (SLRB). The direct method with TIN with Linear Interpolation shows the most negligible absolute error value according to the total error values. Developing countries can benefit from the free access available DEMs by utilizing the fusing techniques proposed in this study to generate better quality DEMs involving almost zero cost.