Elevation data used as input for the generation of contours or the ortho- rectification process is the result of photogrammetric data capture, LiDAR data acquisition or a fully automatic correlation process. After careful terrain analysis, Optimal Geomatic determines the most efficient method of data collection. Break lines, (representing all significant changes in terrain), and mass points are reviewed and edited by experienced technicians in 3D on a softcopy photogrammetric workstation. The resulting digital terrain model can be used for the generation of digital ortho photos or for contours.

Picture of Terrain Modeling in a 3-D view using slopes made by Terra Model	DTM Feature collection of hard and soft breaklines and mass point elevations