Digital elevation model refers to the change in terrain relief or the sudden deviations in slope. Digital terrain models on the other hand represents the terrain height without the elevations. DEM inputs generated will not produce a proper representation of the terrain. So they need to be edited to client specifications by capturing breaklines wherever slope changes are visible and interpolating them to the terrain. SBL conforms to the proper usage of hard and soft breaklines in all its DTM editing assignments. This produces a very good terrain representation resulting in superior quality orthophotos. ASPRS Class I standards will be followed to ensure the accuracy.