GPS/GPX This chapter is about GPS coordinate systems. Map My Land uses GPS coordinates to describe positions on the earth. A position on the earth is identified by measuring the latitude and longitude. The latitude of a point is the number of degrees the point lies from the equator. North of the equator is positive and south is negative. Longitude measures the number of degrees a point lies east or west of a line from pole to pole that passes near Greenwich, England. This line is called the prime meridian. Points east of the prime meridian have a positive longitude and points west of the prime meridian have a negative longitude. All points in North America have a positive latitude and a negative longitude. The latitude and longitude coordinates at the center of the dome of the Capitol in Topeka, Kansas are (39 2' 53.35", -95 40' 41.57"). Map My Land can calculate GPS coordinates for landmarks and boundary points in a property description if the coordinates for the starting point of the property are provided. To enter these values for the starting point of a property, open or create the property and click on the 'Edit Property' button. This causes the MML Property Editor form to display. Checking the box to indicate that the latitude and longitude are meaningful, causes text boxes for latitude and longitude to be displayed. The GPS/GPX features of Map My Land are available when these values are meaningful. When a Latitude and Longitude for a property are meaningful, the status bar reports not only the XY coordinates of the mouse cursor but also the GPS Coordinates 1. In addition, the latitude and longitude are displayed in the Data/Field sheet that is provided on the Print tab in the command panel. 1 Although Map My Land corrects for changes in the horizontal distance per degree of horizontal travel, the change in this ratio within a single property is small. The differences between the two coordinate systems increase with the size of the property.
GPX is a standard form for importing and exporting GPS information. GPX Data includes waypoints, tracks and routes. A waypoint is a named point whose position is specified with a latitude and a longitude. Tracks are essentially a trail of breadcrumbs. The breadcrumbs are waypoints and the trail indicates a path that the user traveled. Routes are also paths but are intended to be followed instead of acting as a record of past travel. Map My Land supports the import and export of waypoints, tracks and routes for properties that have a meaningful latitude and longitude for the property's common point. Map My Land reads GPS Data from GPX Files. Data from some Garmin, Magellan and Lowrance GPS receivers can be saved as GPX Data. Follow the manufacturer's instructions to generate a GPX file from your GPS Receiver. To import GPS data into Map My Land from a GPX file, open a property that has a meaningful latitude and longitude. Then click on the GPS tab in the command panel to reveal the tab page displayed. To import data from a GPX file into the current property, click on the "Import GPX File..." button. This will display the MML GPX Data Importer. The data importer supports the import of waypoints, routes and tracks and allows for the selection of only certain ones of these objects. Click on "Open GPX File..." Select the GPX File you wish to open. Click Open. This will read the data in the GPX File and display it in the tab pages on the right of the GPX Importer as Waypoints, Routes and/or Tracks. This example shows how to read a specific track into the current property.
Select a track that you want to import by clicking on the row header button in the grid. You can select multiple rows from the tables by holding the control key down while you select the rows. If you want to import everything in the GPX file, select "All Items" from the "Items to Import" group. In the example, tracks are chosen to be imported into the Map My Land drawing. First, select a specific track. Next, select the radio button indicating that only the currently selected items should be imported. Lastly, click Import
Clicking the Import button causes the indicated elements from the GPX File to be imported into the property and the image will be updated. Before and after images of the screen with a property called Ada Homes are displayed. Before Import: After Import: Ada Homes Property before importing a GPS Track from a GPX File. Ada Homes Property after importing a GPS Track from a GPX File. (The track information was collected with a Garmin etrex Legend HCx. Map My Land can also export route data that can be imported into some GPS receivers to be used to direct the holder of the receiver around a property. Exporting of routes is also accomplished on the GPS tab. Simply open a property that has a meaningful latitude and longitude and, on the GPS tab page, click on the "Export GPX Route" button. Map My Land will ask for a name and location for the GPX File to be created and then the route will be created that contains all of the corners of all of the properties in the property. The GPX file can then be uploaded to a GPS receiver capable of receiving GPX files and the route can be managed as with any other route on the receiver. See manufacturers' documentation for GPX details.
This example shows how MapSource, the software used with Garmin devices, displays the resulting route. In Map My Land, open the sample property, Provost. Then, on the GPS tab page, click the "Export GPX Route". Enter a filename and select a location that describe where Map My Land is to create the GPX route file on your computer. Now Open MapSource and select File/Open from the main menu. Locate the GPX File saved earlier and open it. Click on the Routes tab in MapSource and right click on one of the routes. Select "Show Selected Route on Map".
The example shows all of the properties on the map. You may need to zoom in or out to make the entire property visible in MapSource. This route can be uploaded to the GPS receiver and used to guide a user around the property.