Demystifying CogoPoint.Latitude and CogoPoint.Longitude API

By Partha Sarkar

AutoCAD Civil
3D .NET
API 2014 Reference document clearly lists the following on CogoPoint.Latitude
and CogoPoint.Longitude –

CogoPoint.Longitude -> Gets or sets
the longitude for a point, relative to the coordinate zone and the
transformation settings specified for the drawing.

public:

property double Longitude {

            double
get ();

            void
set (double value);

}

CogoPoint.Latitude -> Gets or sets
the latitude for a point, relative to the coordinate zone and the
transformation settings specified for the drawing.

public:

property double Latitude {

            double
get ();

            void
set (double value);

}

Let’s explore
this API returned results. First, we need to set an appropriate coordinate system
to our drawing file. For this experiment, I have used CA-II CS code as shown in
the screenshot below –

Now I will
create a COGO Point in the drawing area and we will investigate it’s Latitude
and Longitude values from API and in UI OPM.

Now let’s run
our custom application using Civil 3D .NET API CogoPoint.Latitude and CogoPoint.Longitude.
Here is the code snippet :

ObjectId pointId = points.Add(pointCoord, "My_Test_Point");
CogoPoint cgPoint = trans.GetObject(pointId, OpenMode.ForRead) as CogoPoint;
 
// Point Latitude and Longitude values are in Radians
ed.WriteMessage("nPoint Lat : " + cgPoint.Latitude.ToString() + "  "
                + "Point Long : " + cgPoint.Longitude.ToString());

And here is
the result shown :

In the result
we get decimal values whereas in the Properties window we see the values are in
degree-minute-second. However the values don’t seem to match!

API returned double
values are in Radians. Referring the above screenshot, if we convert the
Latitude value 0.654133960948817 radians to degree we get 37.4791089757124
degree and the Longitude value 2.24952166028165 radians converts to 128.8880756575156
degree.

Hope this is
useful to you!