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<br /> <br />Part 5: Map coordinate systems, projection and scale <br /> <br />A coordinate system is a numerical reference fi'amework for describing the location of some thing. <br /> <br />A proiection is the method by which locations on the curved surlace of the earth are displayed on a nat sheet <br />or surface. Projection involves the use of mathematical transformations between the location of the places on <br />earth and their projected locations on a plane. Both a projection, and a coordinate system arc necessary lor a <br />mapping system. Because the earth's surf.1ce is curved but must be displayed on a nat sheet, there is <br />inevitable distortion of angle, area, directions shapes and distances when the surface is projected. Distortion <br />is usually reduced when the map shows a small geographic area. Some of the more common projections are <br />the Universal Transverse Mercator (UTM) and State Plane Coordinate systems. The data you will use in the <br />Digital Hazard Data class use a coordinate system known as geographic. This is not a projection, It is a <br />spherical reference grid using latitude-longitude coordinates stored in units of decimal degrees. The two <br />world maps shown below use two difterent projections. The map on the left is in Mercator projection and the <br />map on the right is in Behmann Cylindrical Equal-Area projection. <br /> <br />. :~~: ;',....1. ...r <br />~~.{"- ~ ..." <br />,...;t:'~;,.' '..! Ii t.:,t'.' ~~...~~ <br />"'" I ';I;'.~V'" ./1'..-. , <br />Y".. '}\ 1(.'Jj .~ ~,ft <br />,\.',=/., 5~T'1' t~>?'ft) <br />. ".,,~~ ~i~!\~~(:\'-; <br />rr J._ 't:!ff' ~~.....__ <br />'\'. ~4Lt -;.r."r <br />(<'>~' -!<~ L. l-... ') <br />V ,,' / <br /> <br />-"~'-o, '?'-,.~~'~~~~-~=:?T;.'. <br />, "~<i:~ ~al~"'if;' <br />ir-, f r { '"!:.~< <br />'I, r LR/'O /'.'. <br />ft/ \:,.- \. . \ <br />V . / <br /> <br />f <br /> <br />~ <br /> <br />--- -.- <br /> <br />~ <br /> <br />.of <br /> <br />50f9 <br /> <br />3117198 10:05 AM <br /> <br />- <br />