About Setting Geographic Location
Inserting geographic location information to a drawing file makes points within the
drawing correspond to geographic locations on the surface of the Earth.
Geographic location information in a drawing file is built around an entity known
as the geographic marker. The geographic marker points to a reference point in model
space that corresponds to a location on the surface of the earth of known latitude
and longitude. The program also captures the direction of the north at this location.
Based on this information the program can derive the geographic coordinates of all
other points in the drawing file.
Typically a geographic location is defined by its coordinates (for example, latitude,
longitude, and elevation) and the coordinate system (for example, WGS 84) used to
define the coordinates. Moreover, the coordinates of a location can differ from one
GIS coordinate system to another. Hence, when you specify the geographic location
of the geographic marker, the system also captures the details of the GIS coordinate
Typically CAD drawings are unitless and are drawn at 1:1 scale. You are free to decide
the linear unit a drawing unit represents. GIS systems, on the other hand, allow the
coordinate system to decide the linear units. In order to map CAD coordinates to GIS
coordinates, the system needs to interpret CAD drawing units in terms of linear units.
The system uses the setting stored in the INSUNITS system variable as the default
linear measurement of a drawing unit. However, when you insert geographic location
information, you have the option of specifying a different linear measurement (for
a drawing unit).
After you insert a geographic marker in a drawing, you can:
- Make the program automatically determine the angle of sunlight when you perform sun
and sky simulation (photometric studies).
- Insert a map from an online maps service in a viewport.
- Perform environment studies.
- Use position markers to mark geographic locations and record related notes.
- Locate yourself on the map in real-time on systems that support location sensing.
- Export to AutoCAD Map 3D, and expect the model to position itself automatically.
- Import raster files that contain geographic location information and expect them to
position themselves automatically (This requires AutoCAD Raster Design).
the GEOMARKERVISIBILITY system variable.
You can remove geographic location information from a drawing file using the GEOREMOVE
command. The geographic marker and GIS coordinate system are removed from the drawing
file. However, position markers continue to remain in the drawing file.