A transformation is applied only when the geographic coordinate systems are not identical. Transformations relate to the underlying geographic coordinate systems only. See a list of the map projections supported in ArcGIS Pro. For example, the projection may describe how the spheroid coordinates will map to a flat rectangle hypothetically wrapped around the reference spheroid as a cylinder. A projection transforms the angular coordinates (such as latitude and longitude) from the reference spheroid to distance units (such as meters) on a flat surface. Projected coordinate systems always include an underlying geographic coordinate system. Each coordinate system may be either geographic or projected. In ArcGIS Pro, both maps and their layers have coordinate systems, and they are not always the same.
Geodesy datum install#
See Install supplementary coordinate system files to learn more.
Geodesy datum pro#
You can download and install the ArcGIS Pro Coordinate System Data files from My Esri. Some transformations that require files are not installed with ArcGIS Pro. In ArcGIS Pro, the best transformation for your map is suggested based on the data and the extent, but you can specify a different one. The best geographic coordinate system to use depends on where and how much of the earth's geography you are mapping. This real-time translation is sometimes referred to as projecting on the fly. The data is not changed by a transformation. The transformation is a calculation to convert the geographic coordinate system of the layers to match the geographic coordinate system of the map as the map draws so that everything is aligned.
This is necessary because the earth is actually a lumpy and slightly squashed sphere. There is more than one geographic coordinate system because each is meant to best fit certain portions of the earth. They use angular units, such as degrees, to assign locations to coordinates on a reference spheroid. Geographic coordinate systems describe how locations on the earth are placed on a hypothetical reference spheroid. Project data to a new coordinate systemĪ geographic datum transformation is a calculation used to convert between two geographic coordinate systems to ensure that data is properly aligned within a map.
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