Google Mercator Coordinate Reference System

If projected coordinate reference system (CRS) has yet been assigned to the project, then assigning a base map layer (i.e., Hybrid Map Bing, etc.) will automatically assign the Google Mercator coordinate reference system to the project. The Google Mercator CRS allows any location on the globe to be represented as X-Y coordinates.

Advantages of the Google Mercator CRS

  •  The entire spherical globe can be represented by one map.

Disadvantages of the Google Mercator CRS

  • Regions near the earth’s north and south poles are greatly exaggerated. For locations further away from the equator, the amount of X-Y exaggeration increases the further away from the equator the location exists. Therefore, in more northern and southern locations, it would be advisable to switch to a regional (i.e., state plane, etc.) coordinate reference system.518px-Tissot_mercator
  • Only Europe and parts of Asia and Africa lie within the 1st quadrant of the Google Mercator CRS. Therefore, areas outside of the 1st quadrant will have negative coordinates. For example, North America lies within the 2nd quadrant and will have negative X coordinates. Therefore, it would be advisable to switch to a regional (i.e., state plane, etc.) coordinate reference system.tmpD35_thumb2

About the Author Chris Maeder

Chris Maeder

Chris is an experienced civil engineering and software technology leader, with over 30 years industry experience. With proven expertise in global software development, he has built engineering teams that adapt quickly, focus on what’s important and, most importantly, deliver. He is a licensed professional civil engineer with extensive experience in water resource engineering. He has performed and supervised engineering projects in urban stormwater drainage, transportation and roadway drainage, storm sewer design, detention pond design, stormwater quality, green infrastructure, watershed management planning, wastewater sewers, water distribution networks, pump stations, FEMA flood studies, bridge and culvert design, bridge scour and armoring, dam failure analysis, seepage and groundwater modeling, and environmental permits.

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