EMSE 6340 Lecture Notes - Lecture 7: Centroid, Geocoding, Version Control
3 Jun 2016
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Document Summary
Methods of data collection: primary (by direct measurement) - data is captured specifically for use in gis, secondary (derived from other sources) - data is reused from earlier studies or obtained from other systems. Both primary and secondary data can either be raster data or vector data: Raster anything that is pixelated: primary: e. g. aerial photographs, secondary: e. g. scanned maps or photographs, map contours. Vector everything else (e. g. polygon or line: primary: e. g. gps measurements or addresses, secondary: e. g. existing vector data coverage. Remote sensing (has become synonymous with satellite imagery but includes any imagery taken from aircrafts) Most popular and common form of primary raster data capture. Information from measurements of electromagnetic radiation that is reflected, emitted, or scattered from individual objects. Using remotely sensed data: consider projection info (don"t assume that the imagery is preprocessed; need to go through registration/georeferencing if the imagery doesn"t have projection), generate gis layers (turn imagery into identifiable classes of info), update.
