Accuracy Assessment of Openly Accessible CartoDEM V3 R1 and TanDEM-X 90 Using a Smartphone with Assisted GPS for Ratlam City and Surroundings

Abstract

The Digital Elevation Model (DEM) is mostly used to extract the terrain parameters for surface and elevation analysis to represent the topography of the earth’s surface in the best possible way. Nowadays, smart devices such as smartphones and tablets employed with GPS chipsets are easily available in the market. These smart devices can measure elevation data and are cost effective. The relatively plain areas of Ratlam City (Madhya Pradesh) were the study area. A Vivo 1606 smartphone incorporated with Assisted-GPS (A-GPS) was used with a GPS utility App called Mobile Topographer to collect the ground coordinates and elevation data. The ground control points (GCPs) were collected in parts of urban areas, such as open grounds, streets, parks, and other uniformly distributed GCP locations with few GCPs in outer regions of the city. Using smartphone-derived GCPs as a reference, the two openly accessible DEMs—namely CartoDEM V3 R1 and TanDEM-X—were evaluated statistically. Statistical parameters such as Mean Error (ME), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE) were computed for comparative quality analysis between CartoDEM V3 R1 and TanDEM-X 90, using the observed GPS elevation data. The ME (4.60 m), MAE (6.12 m), and RMSE (7.15 m) for TanDEM-X 90 were higher than that of CartoDEM V3 R1, ME (3.09 m), MAE (5.05 m), and RMSE (6.17 m), respectively. The results from the A-GPS Smartphone revealed that the accuracy of CartoDEM V3 R1 is higher and it statistically performs better than TanDEM-X in plain areas of Ratlam using the Smartphone A-GPS.