We accept imagery projected using a standard cartographic projection such as Universal Transverse Mercator (UTM), a satellite-based datum such as GRS80, or WGS84; or in Geographic Coordinates (aka "latitude/longitude") with WGS84 datum. Images should be north-aligned and have rotation parameters set to zero.Each image must be accompanied by one of: a text description of the map projection (WKT), an ESRI .prj file describing the projection or the European Petroleum Survey Group (EPSG) code for the projection. We also accept the projection information embedded directly in the imagery headers.As a general note, we prefer data that has undergone the least amount of transformations, as the resampling process degrades the data with each iteration. If given a choice with no other background information, a projected coordinate system (UTM, national grid, stateplane, etc.) is preferred over a geographic coordinate system (latitude-longitude). This is because pixel dimensions vary with latitude in geographically projected data.
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