3D planimetric feature extraction
With photogrammetric techniques, we can extract all 3d features from the stereo pair images.
The x,y,z coordinates and dimensions for all features can be extracted and can be displayed in the CAD formats.This 3D feature extraction helps in urban planning and development.
Manual contours and breaklines
Contours are not easy to be extracted for high dense vegetation and buildings. In that case with photogrammetry techniques. We can digitize the contours manually for the terrains areas not visible directly. Breaklines area also digitized for the terrain showing.
Digitize manual contours using photogrammetry even for the terrains having mostly covered with trees and buildings making the bare earth not exposed.
A DSM captures the natural and built features on the Earth’s surface.
A DSM is useful in 3D modeling for telecommunications, urban planning and aviation.
A digital elevation model is a bare-earth raster grid referenced to a vertical datum. When you filter out non-ground points such as bridges and roads, you get a smooth digital elevation model. The built (power lines, buildings and towers) and natural (trees and other types of vegetation) aren’t included in a DEM.
When you void vegetation and man made features from elevation data, you generate a DEM. A bare-earth elevation model is particularly useful in hydrology, soils and land use planning.
DTMs are typically created through stereo photogrammetry .A DTM is a vector data set composed of regularly spaced points and natural features such as ridges and breaklines. A DTM augments a DEM by including linear features of the bare-earth terrain.