Drone images classify 3d point clouds to generate DTM and contour lines 

Hello every one, in this lecture you will learn how to generate DTM and Contour line from 3D point clouds using Agisoft Metashape software.
3D point clouds are the thousand of georeferenced 3D points generated
using structure from motion (SFM) algorithm in UAV images overlap area.
SFM uses pixels stereo reconstruction technique to generate point clouds.
Point clouds are used to generate DSM, DTM, conventional orthos and
helpful to take 3d measurement.
DEM vs. DTM vs. DSMThe main difference between the three models is that DEM is a 'bare earth' elevation model which is a superset of DTM and DSM, with DTM being a DEM augmented with features like breaklines and ridges while a DSM being a DTM that includes the natural and human-made features on the earth's surface.