Before revision:  In order to demonstrate the high efficiency of sDEM, we use the problem of total viewshed computation as a case study . Sequential, parallel , single-GPU and multi-GPU implementations are analyzed and compared with the state-of-the-art total viewshed computation algorithm.
After revision:  In order to demonstrate the high efficiency of sDEM, we use the problem of total viewshed computation as a case study considering different implementations for single-core, multi-core , single-GPU and multi-GPU implementations are analyzed and compared with the state-of-the-art total viewshed computation algorithm.