GPS Class that maps Lat/Long to UTM Coordinates (WGS84 and others)

Very nice! I downloaded this for two reasons. The first was to learn how to convert UTM to Lat/Long (and vice versa). The second was as an example of a Class. Being a relative newcomer to the whole OOP thing (though I've had many years of programming experience), I wanted to learn more about it.

Quick question. Would this class be a good place to put conversion routines for doing the various lat/long formats (DMS.dd, DM.dd, D.dd)?

Thanks for the code!
Larry

Absolutely! Classes are as flexible as you need them to be. :D

We are looking to use this in a research project. Is there a license agreement for this code?

Nope, freeware as far as I'm concerned. That's why it's posted on here.

I'm afraid your class is extremely accurate and useful.

Also for peeps who be tryin to convert to C#. This is what I did:
1) Create a VB Library Project.
2) Add the GPS.vb class
3) Compile
4) Start a new C# project
5) Reference the first VB Library Project directly or through the compiled DLL
6) There you can use the class as if it were c#


Anw. Thanks again. You have saved so many lives by posting this code.

It seems like a simple question, but i just cant seem to work it out.

I have Eastings, Northings, Hemisphere and the Zone, I can get the class to work and it outputs Latitudes and Logditudes for me, but they are in DMS, but I really need to get the output in Decimal Long/Lat.

I know im missing something simple.

this is the code i use to output the Long/Lat, is there a conversion function?

Quote:

---

Dim utm As New GPS.UTM(Northing, Easting, Zone)
utm.UTMLatitudeHemisphere = GPS.UTMLat.South

MyLatitude = utm.Latitude.ToString
MyLongitude = utm.Longitude.ToString

---

i feel like it should be

Quote:

---

MyLatitude = utm.Decimal.Latitude.ToString
MyLongitude = utm.Decimal.Longitude.ToString

---

Or something similar.

Thanks, Mike

To get decimal degrees, it's

degrees + (minutes/60) + (seconds/3600)

To get decimal degrees, it's

degrees + (minutes/60) + (seconds/3600)

Quote:

---

Originally Posted by lar3ry

To get decimal degrees, it's

degrees + (minutes/60) + (seconds/3600)

---

I understand the Maths involved, im just unsure of how to implement this. Would i do it in the GPS.vb class or would i do this in my function?

This is a snippet of my code:

Quote:

---

If reader.HasRows Then
While reader.Read()
Northing = reader("Northing")
Easting = reader("Easting")
CarNumber = reader("CarNbr")
Zone = reader("Zone")

Dim utm As New GPS.UTM(Northing, Easting, Zone)
utm.UTMLatitudeHemisphere = GPS.UTMLat.South

MyLatitude = utm.Latitude.ToString
MyLongitude = utm.Longitude.ToString


Lats = Left(MyLatitude, Len(MyLatitude) - 6)
Longs = Left(MyLongitude, Len(MyLongitude) - 5)

'LongsDblQotPos = InStr(Longs, "&#34")
'LongsSnglQotPos = InStr(Longs, "'")
'LongsMin = Mid(Longs, 6, Len(Longs) - 7 - LongsSnglQotPos)
'LongsSec = Mid(Longs, LongsSnglQotPos + 2, Len(Longs) - (LongsSnglQotPos + 2))

'LongsDecimal = (((LongsSec / 60) + LongsMin) / 60) + 27


'LatsDblQotPos = InStr(Lats, "&#34")
'LatsSnglQotPos = InStr(Lats, "'")
'LatsMin = Mid(Lats, 5, Len(Lats) - 6 - LatsSnglQotPos)
'LatsSec = Mid(Lats, LatsSnglQotPos + 2, Len(Lats) - (LatsSnglQotPos + 2))

'LatsDecimal = CDbl(Val((((LatsSec / 60) + LatsMin) / 60) + 153))

My.Computer.FileSystem.WriteAllText("C:\TestCopy.txt", "['Car:" & CarNumber & "'," & " -" & Lats & "," & " " & Longs & ", " & index & "]" & Chr(10), True)

index = index + 1

End While


End If

---

It reads the values from a DB then converts them from UTM to Lat Long, but my application needs lat longs in decimal format. Im just unsure of how to do that.

Dismiss my last question... it seems with a little more obvious thinking i worked it out!

Quote:

---

If reader.HasRows Then
While reader.Read()
Northing = reader("Northing")
Easting = reader("Easting")
CarNumber = reader("CarNbr")
Zone = reader("Zone")

Dim utm As New GPS.UTM(Northing, Easting, Zone)
utm.UTMLatitudeHemisphere = GPS.UTMLat.South

MyLatitude = utm.Latitude.ToString
MyLongitude = utm.Longitude.ToString

LatsDecimal = utm.Latitude.Degrees + (utm.Latitude.Minutes / 60) + (utm.Latitude.Seconds / 3600)
LongsDecimal = utm.Longitude.Degrees + (utm.Longitude.Minutes / 60) + (utm.Longitude.Seconds / 3600)

My.Computer.FileSystem.WriteAllText("C:\TestCopy.txt", "['Car:" & CarNumber & "'," & " -" & LatsDecimal & "," & " " & LongsDecimal & ", " & index & "]," & Chr(10), True)

index = index + 1

End While


End If

---

Hi Jenner - I have implemented your code to geolocate aerial images - and the locations are only somewhat close. I have a centroid located at 35.44752324, -119.0344939 and the UTM comes out as 11N 3925110.67478774, 314745.859021866 - this is about 373 and 741 meters off. The Lat/Lon are in WGS84, and I am loading the resulting UTM Arcmap using NAD83_UTM_Zone11 as my projection. . Thanks for your help

I see a lot of posts here requesting decimal Lat/Long output instead of ddd mm' ss.ss".

So, I added two read only properties to the class. Here is the code with the new parts highlighted:

Added two local private double variables...

Code:

---

    Public Class UTM
        Private Const k0 As Double = 0.9996


        Private cooLat As New Coordinate(0, CoordinateType.Latitude)
        Private cooLong As New Coordinate(0, CoordinateType.Longitude)
        Private utmDat As UTMDatum = UTMDatum.WGS84
        Private dblNorthing As Double = 0
        Private dblEasting As Double = 0
        Private DecLat As Double = 0.0
        Private DecLong As Double = 0.0
        Private utmL As UTMLat = UTMLat.North
        Private intZone As Int32

---

Added two read only properties...

Code:

---

#Region "Properties"
    .
    .
    .
      Public ReadOnly Property DecLatitude() As Double
            Get
                Return DecLat
            End Get
        End Property

        Public ReadOnly Property DecLongitude() As Double
            Get
                Return DecLong
            End Get
        End Property
    .
    .
    .
#End Region

---

Filled in the private class variables with the values in the UTM to LL conversion ....

Code:

---

        Public Sub GetLatLong()
                    .
                    .
                    .
            cooLat = New Coordinate(Convert.ToDecimal(lat), CoordinateType.Latitude)

            DecLat = lat

            Dim lon As Double = GetZoneCM() - ((lof1 - lof2 + lof3) / Math.Cos(phi1)) * 180 / Math.PI

            DecLong = lon

            cooLong = New Coordinate(Convert.ToDecimal(lon), CoordinateType.Longitude)
        End Sub

---

My question to the forum here is, has anyone seen a class like this, but for U.S. State-Planes <-> LatLong ?

Korg sends

I have been testing the class and it works well ... thank you.
When I try to convert a UTM coordinate to a Lat/Long coordinate, the latitude is off slightly but the longitude is the same. I am comparing my results to the National Resources Canada website at:
http://webapp.geod.nrcan.gc.ca/geod/...outils/trx.php.

The values I am using are:
N: 5453095.17
E: 704731.39
Zone: 13

The results I get from the class are:
Lat: 49.196384246396228 (49° 11' 46.9833")
Long: -102.18969397760389 (-102° 11' 22.8983")

but the results from the Geodetic site are:
Lat: 49° 11' 47.17321"
Long: -102° 11' 22.89833"
From other samples I tested, it appears that the longitude is always the same but the latitude is always off a bit.

Here is the code I am using:

Dim utm As New clsGPS.UTM(myNorthing, myEasting, Zone)

utm.UTMLatitudeHemisphere = clsGPS.UTMLat.North
lat = utm.Latitude.GetDecimalCoordinate
lon = utm.Longitude.GetDecimalCoordinate

Am I missing something?
Blair

I made some changes in the function GetLatLong() that solve the problem in the south hemisphere, added local variable dNorth and dEast :

Dim dNorth As Double = 0
Dim dEast As Double = 0
' dblNorthing = If(utmL = UTMLat.North, dblNorthing, 10000000 - dblNorthing)
dNorth = If(utmL = UTMLat.North, dblNorthing, 10000000 - dblNorthing)
dEast = dblEasting
Dim arc As Double = dNorth / k0