Coordinate Questions in the Web Environment

This article contributes to the clarification of the coordinate reference systems (CRS) used by some Web mapping appli- cations. This is a complex issue, mainly because of a lack of pertinent information; there is little published literature on CRS, and information available online – which is not produced by mapping experts – is fragmented and often imprecise. Following a short introduction focusing on Web mapping and the European Petroleum Survey Group (EPSG) database, which is currently maintained and published by the International Association of Oil and Gas Producers (OGP) Geomatics Committee, the article analyzes the CRS used by some well-known Web mapping applications, such as Google Maps and Bing Maps (planimetric browsers) and Google Earth (virtual globe). Some geodetic technical information is given, with reference to the main desktop GIS software libraries and to reports on CRS queried from different versions of the EPSG database (2008–2013).