African Geomatics
Topographical Surveys
Topographical surveys record the terrain and natural and man-made features of a site. They provide essential information for planning and designing buildings, roads, railways and other infrastructure. Depending on the project requirements, a survey may include ground elevations, contour lines, buildings, roads, drainage features and existing services.
Site surveys are carried out to support the planning and design of proposed developments, including buildings, roads, radio towers and other infrastructure. They combine a detailed survey of existing features with information about the terrain, typically presented as a contour plan. This provides designers and engineers with a comprehensive view of the site before construction begins.
A contour plan represents the shape and elevation of the terrain using contour lines, each connecting points of equal elevation relative to a specified vertical datum. The spacing between contour lines indicates the steepness of the terrain: closely spaced lines represent steeper slopes, while widely spaced lines indicate gentler slopes. The contour interval is the vertical difference in elevation between successive contour lines.
Detail surveys locate and record natural and man-made features within a survey area. These may include buildings, walls, roads, manholes, overhead telephone and power lines, pipelines, trees and other relevant features. The surveyed positions and details are shown on a plan and can be used for engineering design, infrastructure planning and site development. Contour information can be included where required.
A Digital Terrain Model (DTM) is a digital representation of the bare ground surface, with vegetation, buildings and other above-ground features excluded. It describes the underlying terrain and can be used for contour generation, earthwork calculations, drainage analysis, engineering design and other terrain-related applications.
A Digital Surface Model (DSM) represents the upper surface of an area, including buildings, trees, vegetation and other above-ground features. It can be generated from UAV imagery and is used for 3D mapping, height measurements, visibility analysis and infrastructure planning.