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Georeference drawing



Before you can use some CAD-Earth commands you must georeference your drawing to define parameters like translation, rotation and scale to convert between drawing and latitude/longitude coordinates. This ensures that imported images and objects from the real world will be correctly placed in your drawing and when exported they will check with real geodesic coordinates.


You can georeference your drawing by any of the following methods:


By geolocating drawing objects in a map. This is the easiest method to georeference a drawing. You have to select some reference entities in your drawing (like lines or polylines) and locate them in a map. You can move, rotate and scale the reference objects until they are correctly placed. This is the least accurate method of georefence because the objects can only be approximately placed.

By selecting two points in the drawing and typing their latitude/longitude coordinates. If you know the corresponding geodesic coordinates of at least two points in your drawing the georeference parameters can be calculated with this information. The accuracy of the conversion calculations will depend on the precision of the latitude/longitude coordinates given.

By selecting a coordinate system. This is the more accurate way of converting between drawing and latitude/longitude coordinates, because all the conversion calculations are purely mathematical. You must know the coordinate system used when the drawing was made and the drawing coordinate extents must correspond with the real site, otherwise you'll have to almost certainly try several coordinate systems until the images and objects are correctly placed.

By loading georeference parameters from an existing file. If you have previously saved georeference parameters to a file from another drawing you can use the command to load georeference parameters from file to georeference a drawing that shares the same geolocation.

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