MAPMAKING
Scientific methods of surveying and mapping expanded greatly in the 17th, 18th, and 19th centuries, in part due to more sophisticated mathematical applications as well as rigorous, comprehensive surveys of large areas.
Surveying today often employs elements of remote sensing obtaining information about an object or an area from a distance. Looking down on a city from the top of a tall building or on a village from the top of a tall
mountain is a form of remote sensing Mapmakers use more sophisticated methods to get similar results.
Aerial photography, used to some extent during World War I, became widespread during World War II as a remote-sensing tool in mapmaking. It eliminated much of the legwork for surveyors and allowed precise surveying of some otherwise inaccessible places.
Remote sensing by radar, or radio waves, and sonar, or sound waves,
provides another way to record surface features of the land or the ocean floor In both methods, distance is calculated from the time it takes the waves to travel to and from the target area
Remotely sensed images vary by the kind of resolution they portray
Spatial resolution refers to how sharp an image is. Greater distance usually equates with fuzzier images
Spectral resolution refers to which part of the light spectrum is being cap tured and can include such wavelengths as visible light or infrared light.
Temporal resolution refers to the time frame represented. This tech nique uses sequential images of an area to show changes over a period of time.
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