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COGO (Coordinate Geometry) Points
You can import LandXML COGO (Coordinate Geometry) points and convert
them to AutoCAD points.
Civil engineers create COGO points to locate crucial surveying locations. A
COGO point can be a project benchmark point - a common datum that the
entire civil team works off and from which all critical dimensions are located.
NOTE A LandXML file usually contains a large number of COGO points. In most
cases, you need only a small set to work within the drawing. You do not need to
import all COGO points, only those that have a special meaning for the drawing.
COGO points are the foundation for any civil engineering or surveying project.
In Land Desktop, you can use description keys to place points in the drawing
with symbols on specific layers. When importing a LandXML file you can
map selected points to the appropriate layer.
When a COGO point is imported it is defined by its coordinates in the form
of “northing easting” or “northing easting elevation.”
For example, a COGO point could be represented as: <CgPOINT NAME="1"
DESC="MYPOINT">248.04605951 359.53997314 1.000000</CgPOINT>.
COGO points on a map
NOTE Autodesk Land Desktop uses two coordinate systems for locating points:
X,Y and northing/easting. When you start a new project, these values all default
to 0 so that the Y coordinate is the same as the northing, and the X coordinate is
the same as the easting. Unless you change that in Land Desktop before exporting
a drawing to LandXML, the exported northing value will be identical to Y and the
exported easting value will be identical to X.
Surfaces
In most surveying and civil engineering operations, you gather information
about elevations to generate surface contours that represent a model of the
ground surface. The surfaces in LandXML are made up of many faces which
are either TINs (Triangular Irregulated Networks) or quadrilaterals. Points or
contours are usually a primary part of the original surface information and
248 | Chapter 5 Interoperability with Other Applications
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