Short note: Define photogrammetry, GIS applications

Photogrammetry

Photogrammetry is the science and art of obtaining reliable measurements, maps and three-dimensional information of objects and the Earth's surface from photographs, usually overlapping aerial photographs. It is used to prepare topographic maps, DEMs and orthophotos.

Application of GIS in civil engineering and mapping

A GIS stores, analyses and displays spatial data in layers.

• Mapping: digitising and storing base maps, thematic maps (land use, soil, geology) and cadastral maps; updating of maps; combination with remote sensing and photogrammetry products (orthophotos and DEMs).
• Route and site selection: overlay of terrain, land use, geology and cost layers for road, canal, pipeline, dam and bridge location.
• Urban and regional planning: land use zoning, population and growth analysis, infrastructure planning.
• Utility and asset management: water supply, sewer, power and road networks.
• Water resources: catchment and drainage analysis, flood modelling, irrigation planning.
• Disaster management: landslide, flood and earthquake hazard and risk maps; relief planning.
• Environment: impact assessment and monitoring of land cover change.
• Transportation: traffic and accident analysis, shortest path and network analysis.
• Construction: terrain models, cut-and-fill volumes and project monitoring.