![]() ![]() Create a custom projected coordinate system in ArcGIS Pro with an extent and projection property.Access the UTM Grid reference layer in ArcGIS Living Atlas of the World.Copy and modify existing projected coordinate systems in ArcGIS Pro.Perform keyword searches and spatial filters in ArcGIS Pro.Review the ArcGIS help documentation for supported map projections. ![]() Consult the Quick Notes on Map Projections in ArcGIS chart.In this tutorial, you learned some techniques and explored resources that will help you choose an appropriate map projection: Change the central meridian to 160°W or a similar value. Change the central meridian to 29.9.Ĭopy and modify the Equal Earth (world) coordinate system. ![]() How could you modify an existing UTM coordinate system to center it on the Russia-Finland border? How could you modify the Equal Earth projection from the start of this tutorial to better show the Pacific Ocean?Ĭopy and modify any WGS 1984 UTM Zone coordinate system. Distortion in the Transverse Mercator map is small enough to be unnoticeable, and more precise measurements can be made on that map.Įarlier in this tutorial, you learned how to modify coordinate systems. ![]() But that scale is meaningless in the Web Mercator map, since its area distortions are so extreme. The two maps shown above are drawn at the same scale: 1 to 20 million. The new projection represents them more accurately. The rectangle in Web Mercator is misleading: on the earth, these lines are not the same length. Its northern edge is shorter than its southern edge. In the custom coordinate system, the shape of the neatline polygon is a trapezoid instead of a rectangle. The image below shows a comparison of the map in the new custom projected coordinate system and in Web Mercator. You want to choose a projected coordinate system in which the places and properties that are most important to your map are the least distorted. Your choice of a projected coordinate system depends on many factors, including the part of the world you are mapping, the scale of your map, and the purpose of your map. There are dozens of projections available in ArcGIS that can be configured into countless projected coordinate systems. They are usually used for maps of the entire world. Three maps, drawn with examples of conformal, equal area, and equidistant projections, overlaid with geodesic circles that demonstrate geometric distortions.Ĭompromise projections provide a representation of the earth that is not perfectly correct in any way but not badly distorted in any way either. Equidistant projections preserve distances, although only from certain points or along certain lines on the map. Equal area projections preserve area, at the expense of angles, so the shapes of some places appear skewed. But the cost of this quality is the distortion of areas and distances. Projection typesĬonformal projections preserve angles locally, so the shapes of features appear true. Each one seeks to preserve some geometric property at the expense of others. All projections distort the earth in some way. Grid values to the west of this central meridian are less than 500,000 to the east, more than 500,000.You will not find a projection that is suitable for all maps. A central meridian through the middle of each 6° zone is assigned a "false" easting value of 500,000 meters. Southerly values are similarly measured from the Equator, south. (One meter equals 39.37 inches, or slightly more than 1 yard.) The northing values are measured continuously from zero at the Equator, in a northerly direction. In each zone, coordinates are measured north and east in meters. Thus, the conterminous 48 States are covered by 10 zones, from Zone 10 on the west coast through Zone 19 in New England. These zones are numbered consecutively beginning with Zone 1, between 180° and 174° west longitude, and progressing eastward to Zone 60, between 174° and 180° east longitude. In this grid, the world is divided into 60 north-south zones, each covering a strip 6° wide in longitude. The Universal Transverse Mercator (UTM) grid is an X-Y coordinate system used as a reference on medium- to small-scale maps for representing the three-dimensional curved surface of the earth on a 2-D plane (e.g. ![]()
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