4. Results and discussion
In this section, we present and discuss the results of the accuracy assessment of the proposed algorithm. Accuracy of the algorithm was evaluated in three ways: (1) by visually inspecting the produced DTM; (2) by comparing tree height estimates obtained using the produced DTM with field measurements; and, (3) by testing the algorithm against the International Society for Photogrammetry and Remote Sensing (ISPRS) Commission III/WG3 test data set (See Sithole and Vosselman, 2004).