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UTM

UTM stands for Universal Transverse Mercator. It is a Transverse Mercator map projection which can be used at any place on the globe. To cover the whole earth, the system is divided into multiple grids, using 60 zones, each covering 6 degrees which is about 800 kilometers in width.

Each zone is defined for both the northern and southern hemisphere. Therefore the zones are called zone 1N - zone 60N for the northern hemisphere and zone 1S - zone 60S for the southern hemisphere.

This document is going to explain, how you can add support for UTM coordinates to your Visual Basic .NET projects.

UTM Zones

The following table describes which zone should be used on any given location on the earth, and its associated Transverse Mercator parameters:

The Eye4Software GPS Toolkit

The Eye4Software GPS toolkit allows software developers to add GPS functionality to their own programs without the need to have any knowledge on serial communications and GPS protocols like RS-232 and NMEA0183.

The product can be used in many programming environments, such as Visual Basic, Visual C++, Visual Studio.Net, Borland C++ Builder, Borland Delphi and VBA, but also web oriented applications such as ASP, ASP.NET and PHP, and all other programming environments that support ActiveX.

Prerequisites

First you must have Visual Basic .Net and the Eye4Software GPS Component installed on your computer. We will use Visual Basic .Net 2003 in this document, but other versions from 2002 and up can be used. You can download the Eye4Software GPS Component here.

Creating the project

Start the Visual Studio IDE, and select the "New" => "Project" option from the "File" menu. The "New Project" dialog now appears, select the "Windows Application" option to generate a Windows GUI application.

Add a reference to the ActiveX component

In order to declare and create the objects from your Visual Basic .Net application, you need to add a reference to the ActiveX object, by choosing the "Add Reference..." option from the "Project" menu. A list of components installed on the system is displayed. Just select the "COM" tab, and select the "Eye4Software GPS Toolkit 3.0", click "Select" and finally click "OK".

Declare and create the object(s)

After adding the reference to the control, you can declare the objects like this:

Private objProjection As GpsProjection
Private objDatum      As GpsDatumParameters

The objects can be created in your code by double clicking on the Form you created, this will open the Formx_Load handler. Paste the following code in this function:

objProjection = New GpsProjection
objDatum      = New GpsDatumParameters

The source code

The source code below demonstrates how to add latitude / longitude to UTM transformation functionality to your program using the GPS Toolkit. In this example a position is transformed from WGS84 to UTM ED50. Using the 'ToUTM' function, the software will automatically calculate the UTM zone for the given position. To perform a inverse calculation use the 'FromUTM' function.

' ConvUTM Visual Basic .NET demo - Eye4Software GPS Toolkit
' This demo shows how to convert a latitude/longitude coordinate to an UTM coordinate for any given map datum.
' For more information on how to use the Eye4Software GPS Toolkit with Visual Basic .NET, 
' visit http://www.eye4software.com/products/gpstoolkit/source#vbnet

Imports GpsToolkit

Module Module1
  Private objProjection As GpsProjection
  Private objDatum      As GpsDatumParameters

  Sub Main()
    objProjection = New GpsProjection
    objDatum      = New GpsDatumParameters

    ' Set Datum ( ED50 )
    ' The ID for ED50 is 4230, see 'http://www.eye4software.com/resources/datums' for a full list of supported datums 
    ' To use UTM with another map datum, just change the code below (EPSG code)
    objDatum.LoadFromId (4230)

    ' Set source latitude and longitude
    objProjection.Latitude  = 55.40
    objProjection.Longitude = -2.89

    ' Perform map grid transformation
    objProjection.ToUTM ( objDatum )
    
    ' Get and display result
    If (objProjection.LastError = 0) Then
      Console.WriteLine("(WGS84) 55.400 N, 2.890 W => (UTM ED50) Norhing: {0}, Easting: {1}", 
                        objProjection.Northing, objProjection.Easting)
    Else
      Console.WriteLine("Error occured during map grid transformation: {0} ({1})", 
                        objProjection.LastError, objProjection.LastErrorDescription)
    End If

    Console.WriteLine("Ready.")
  End Sub
End Module