We have been talking about different elements of mapping, and this week’s term is hachure. This refers to a technique of strokes that indicate orientation of slopes and the general sense of steepness in a geographical area. Shading can also be used to provide a depth of information in regard to the geographical attributes of an area.
Photogrammetry is the science of creating measurements from aerial imagery, especially for plotting the exact positions of surface features. Its use is as old as photography itself. It is used in topographic mapping to assist in showing natural and manmade features, as well as in many other fields, such as meteorology, for determining the actual wind speed of a tornado.
The term this week is graticule, which is defined as the network of lines of latitude and longitude upon which a map is drawn, and refers to the rectangular zones between those lines.The shape and size of each graticule over the ground varies with the distance from the equator.
WGS84, or the “World Geodetic System 1984” is a specific datum that was first modeled in 1984 and has been subsequently refined, most recently updated in 2004. It was produced using highly-accurate readings from space, made using satellites equipped with advanced laser, radar and other complex measuring equipment. This is the datum most frequently used today for general cartography and naviga