Performances evaluation of different open source

Abstract

In Open sources DEMs such as SRTM, ASTER and Cartosat-1, various factors affecting the accuracy of satellite based DEM such as errors during data collection, systematic errors and unknown errors that are geographically dependent on terrain conditions cannot be avoided. For these reasons it is very necessary to check and compare the performances and validation of the above mentioned different satellite based DEMs. Accuracy assessment of these DEM has been done using DGPS points. For these points proper interpolation of the surface was developed using different interpolation techniques. For the generation of the surface the first step was converting the satellite based DEMs height into linear interpolation contour maps of 1 m interval. Then came selecting random sample points on the contour line and generating the interpolated surface using different interpolation techniques such as IDW, GPI, RBF, OK and UK, LPI, TR and BI, which are commonly used in geomorphology research. This interpolated surface helps in proper representation of the terrain and was checked under different terrain surfaces. For validation of DGPS points the height was taken for ground control points and standard statistical tests such as ME and RMSE were applied. From above investigation, it is reveals that above mention DEMs which are used for study. Cartosat-1 (30 m) data product is better than SRTM (90 m) and ASTER (30 m) because it had produced low RMSE of 3.49 m without applying the interpolation method. Investigation also reveals after applying the interpolation techniques on this data error can be reduced. In the case of Cartosat-1 and SRTM, low RMSE and ME were produced by the BI method, where Cartosat-1 DEM had an RMSE of 3.36 m with ME of −2.74 m, respectively. But in this case, RMSE and ME of SRTM is 2.73 m and −0.36 m, respectively. BI is designed for image processing and can be used for imagery were a maximum height variation in satellite DEM and terrain height is minimum. But in the case of ASTER DEM, the GPI method with a high polynomial order of 9 had produced a low RMSE of 4.99 m. The GPI method can be applied where maximum height variation in satellite DEM and in terrain is more.

Keywords

• SRTM
• ASTER
• Cartosat-1
• Interpolation techniques
• DGPS
• GIS