Change detection (GIS)

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In geographic information system (GIS), change detection is a process that measures how the attributes of a particular area have changed between two or more time periods. Change detection often involves comparing aerial photographs or satellite imagery of the area taken at different times. Change detection has been widely used to assess shifting cultivation, deforestation, urban growth, impact of natural disasters like tsunamis, earthquakes, and use/land cover changes etc. [1]

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<span class="mw-page-title-main">Remote sensing</span> Acquisition of information at a significant distance from the subject

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3D Structure Change Detection is a type of Change detection (GIS) processes for GIS. It is a process that measures how the volume of a particular area have changed between two or more time periods. A high-spatial resolution Digital elevation model (DEM) that provides accurate 4-d structural information over area of interest is required to compute such changes. In production, two or more DEMs that cover the same area are used to monitor topographic changes of area. By comparing the DEMs made at different times, structure of terrain changes can be realized by the ground elevation difference from DEMs. Details, occurring time and accuracy of such changes are strongly relied on the resolution, quality of DEMs. In general, the problem of involves whether or not a change has occurred, or whether several changes have occurred. Such structure changes detection has been widely used to assess urban growth, impact of natural disasters like earthquake, volcano and battle damage assessment.

<span class="mw-page-title-main">Remote sensing (geology)</span> Remote sensing used in the geological sciences as a data acquisition method

Remote sensing in geology is remote sensing used in the geological sciences as a data acquisition method complementary to field observation, because it allows mapping of geological characteristics of regions without physical contact with the areas being explored. About one-fourth of the Earth's total surface area is exposed land where information is ready to be extracted from detailed earth observation via remote sensing. Remote sensing is conducted via detection of electromagnetic radiation by sensors. The radiation can be naturally sourced, or produced by machines and reflected off of the Earth surface. The electromagnetic radiation acts as an information carrier for two main variables. First, the intensities of reflectance at different wavelengths are detected, and plotted on a spectral reflectance curve. This spectral fingerprint is governed by the physio-chemical properties of the surface of the target object and therefore helps mineral identification and hence geological mapping, for example by hyperspectral imaging. Second, the two-way travel time of radiation from and back to the sensor can calculate the distance in active remote sensing systems, for example, Interferometric synthetic-aperture radar. This helps geomorphological studies of ground motion, and thus can illuminate deformations associated with landslides, earthquakes, etc.

References

  1. Wade, T. and Sommer, S. eds. A to Z GIS