Sometimes you're given a set of X,Y or Easting,Northing data in an unknown coordinate format. Here are some tricks to make it easier to determine the correct coordinate format using ExpertGPS.

It's usually a simple task to tell the various lat/lon formats apart, but when given unknown gridded X,Y data, it can be difficult to tell if it is in UTM, US State Plane, or a national grid format, since all three use Eastings and Northings. I help ExpertGPS users convert data every day, and I often get emailed X,Y data without knowing the proper coordinate format. If this ever happens to you, try the following:

Where is this data from?

My first question, when an ExpertGPS doesn't know the exact origin of the data, and therefore the coordinate format used, is "what town does this data cover?" For this tutorial, let's try to figure out the correct format for these coordinates: 145537, 4291885, which should be located somewhere around Alpine, TX.

Since the data is in the United States, and these clearly aren't latitude/longitude coordinates, and US National Grid coordinates would be formatted differently, we know we're dealing with UTM or US State Plane coordinates.

Picking the right US State Plane Coordinate System

ExpertGPS.com has a reference list of every US State Plane coordinate system. Clicking on the link for Texas SPCS lists several possibilities: TX South, TX South Central, TX Central, TX North Central, Texas North, as well as the Texas Statewide Mapping System and Texas Centric Mapping System Lambert.

You could try converting your data using each of these State Plane systems, and see which one gives the correct results. Luckily, ExpertGPS.com also lists the counties each of these coordinate systems cover. A quick Google search for "Alpine TX county" reveals that Alpine is in Brewster County. The Texas SPCS page on ExpertGPS.com shows Brewster County is covered by Texas South Central SPCS (as well as the Statewide and Lambert systems).

Comparing your X,Y coordinates to the formats in ExpertGPS

To make it really easy to find the correct coordinate format, I've built a special feature into the Add Coordinate Formats dialog that instantly shows the coordinates for the location you're viewing on the map in each format listed in the Add Coordinate Formats dialog. To take advantage of this, you'll need to load some data for the general area where your mystery data is located. I used the Go to Address command, and had ExpertGPS create a waypoint at the city center of Alpine, TX. With the map centered on Alpine, I clicked Preferences on the Edit menu, and clicked on the My Coordinate Formats tab. I clicked Add, and the Add Coordinate Format dialog appeared.

As you scroll through the list of coordinate formats listed for Texas, you'll see the results of Alpine's location (lat/lon N30.36061, W103.67280) projected into eastings and northings in each Texas State Plane coordinate format. Scroll through the list until you find a sample that is close to the X,Y data you're importing. In this case, TX South Central (Meters), NAD83 gives these coordinates for Alpine: 151671N, 4288824E, which is very similar to (and only a few kilometers away from) our unknown coordinates: 145537N, 4291885E).

Once you've found the correct coordinate format and datum to use, click OK to add this format to ExpertGPS.

Paul R. asks:
For a project, I am using a Google Maps API application to create cycling routes. I am creating the routes in the Google Maps API application because the ultimate target application also runs on the Google Maps API. I have very limited export options but I can export tracks in kml format. I can import these kml files into ExpertGPS and I can then export from ExpertGPS the files I need for my application. One of the file types that I export from ExpertGPS for use in my application is a text-delimited tracking file. My problem is that I would like to have elevations in the exported tab-delimited tracking file, but at the moment I can't figure out how to do that.

The July 2009 release of ExpertGPS features a new tool to calculate the elevation of any location in the world, and add that elevation data to any waypoint, route, or track. In the past, when you drew a track on the map in ExpertGPS, or imported driving directions or trails from Google Earth or another 2D mapping source, you wouldn't have elevation data available. Now, using the Get Elevation command on the Tools menu in ExpertGPS, you can add elevation to anything. Simply select the waypoints, routes, or tracks on the map, and click Get Elevation. ExpertGPS will determine the elevation for each point, using the best-available data from the US Geological Survey and NASA's Space Shuttle Radar Tomography Mission (SRTM). In a few seconds, you'll have elevation data, and you can use the Show Elevation Profile command on the View menu to plot the elevation at every point along your hike, ride, or drive.

Jim asks:
I would like to hike trails in various park locations throughout the US ( mostly Tampa area, FL). I can find the addresses online and usually a general map of the trails. Many of these trails are miles long, however, and marked with numbered posts along the way. None of this has GPS coordinate info. Often, the paths will cross each other with limited marking. Can Expert GPS help with this? If I input an address ( a state park ), would the map zoom in enough to show trails and would can you set waypoints along the trails with the coordinates? To what extent can this be downloaded to the GPS?

You can use the Scanned Maps feature in ExpertGPS to display a scanned paper trail map, or a digital copy of the Tampa-area trail map. Many state and federal parks have maps available in PDF format. Adobe's Acrobat Reader will allow you to select the entire map image, copy it to a bitmap, and paste it into your favorite image editing program. You can then save it in PNG or JPEG format for use in ExpertGPS.

Once you've scanned or downloaded your trail map, the next step is to calibrate your scanned map so that ExpertGPS can calculate the GPS coordinates of every pixel in the scanned map image.

After your map is properly calibrated (geo-referenced), you can then trace trails right over the map, or click to add waypoints at trail intersections.

How I use the Scanned Maps Feature

One of my favorite mountain biking locations has dozens of overlapping trails, and we would often get confused as to exactly which intersection we were at. I scanned the trail map, brought it into ExpertGPS, and traced every trail and labelled every intersection. Before each ride, we'd download this data to our Garmin eTrex GPS receivers, and mount them on our handlebars. Now we always knew exactly where we were. Once we established a favorite route, we used ExpertGPS to string the waypoints at each intersection together to create a turn-by-turn route. Now the GPS could tell us how far until the next turn, and which way to go at each intersection.

An ExpertGPS user asks:
When I trace a stream over the map in ExpertGPS, why does ExpertGPS connect the end of my drawn shape back to the beginning?

The short answer: because you are drawing with a filled shape type. ExpertGPS allows you to assign a cartographic style to the objects you draw on the map. Every shape, track, and waypoint in ExpertGPS has a Type that you assign. You define the cartographic style (color, line pattern, fill color) for that Type in the Edit Type dialog (the Edit Shape Type dialog is shown below). For Routes, Tracks and Shapes, you can choose a fill pattern. Obviously, only filled objects should have a fill pattern. A lake would have a blue fill. A stream, being a linear object, shouldn't have any fill. It should just have a blue line color.

Automatic Closing of Filled Shapes

When you draw a new object on the map, and assign it a filled shape type, ExpertGPS automatically closes the shape (by connecting the last point you drew back to the beginning point). Otherwise, you'd end up with lakes with holes in them, and your map would get all wet!

You can manually close any route, shape, or track by selecting it, right-clicking, and clicking Close. To save you this effort, ExpertGPS does it automatically when you assign a filled type to something you've just drawn on the map.

So, if you are tracing the lakes, ponds, streams, and creeks of your area off the topo maps, you should create two Shape Types: Lake and Stream. Lake would have a Solid fill, and Stream would have fill set to None. Choose the Lake type for any body of water (lake, pond, reservoir) and Stream for any linear waterway (stream, creek, canal).

To learn more about the power of ExpertGPS' cartographic styles and types, read Working with Types in the ExpertGPS Help File.

Stacy X. asks:
What is the best method to create a gpx or kml file of an area filled polygon that has islands (a lake shp file). When I export as a gpx, it creates a polyline where the end node of the lake outline connects to the end nodes of each of the islands. When I export as a kml, the fill of the polygon is not complete. The strange part is when you zoom in, the lake polygon will fill; then if you zoom out, it empties.

ExpertGPS Pro allows you to draw, view, and import polygons with complex geometry, including filled objects with holes in them. You can use this feature to draw lakes with islands, a park boundary with private land inholdings, or other complex shapes. Here's how to create the "donut" shown at right.

Begin by drawing the outer shape, using the shape tool. I clicked to draw the four corners, and then pressed Enter to finish the drawing and connect the fourth corner back to the start. (This happens automatically when you select a filled shape type)

I then drew the inner hole using the shape tool. Add the shape points in counter-clockwise order! This is important - most GIS and 3D systems consider counter-clockwise polygons to be inner holes.

Once the two shapes are drawn, select both by clicking the outer one with the Select tool, holding Shift, and selecting the inner one (or ones, if there are multiple holes). Right click, and click Join Shapes to convert the selected shapes into one composite shape. ExpertGPS will recognize the inner holes and leave them unfilled. If you calculate area, ExpertGPS will subtract out the area of any inner polygons, giving you the correct acreage of your lake or property.

You can now export the shape to your GIS software in shapefile format, or click View in Google Earth to see the lake or property boundary over the aerial imagery in Google Earth.

Michael O. writes:
I am having issues with the creation of shapes. I have found that as I am creating a shape, I cannot change the location of a particular shape point. The only recourse I can determine is to redo the whole shape. In some cases this means retracing a large number of points. (Landing zones, training areas, and so on are not regular shapes and highlighting those areas on maps is highly desirable.) In looking at the shape list, I don't see any means of editing the shapes.

Use the Move Selected tool to select the entire shape. It will be drawn in yellow, and each individual shape point will appear as a white dot. Drag a selection rectangle around the shape point you want to move. It will be highlighted in magenta. Now drag it to its new location. To get rid of the purple highlight, click Clear Selection on the Tools menu.

Related Topics Move Selected tool

ExpertGPS author Dan Foster writes:
Here are 10 mapping shortcuts that will save you lots of time when working with maps and GPS data in ExpertGPS. I use these shortcut keys and tricks dozens of times a day to save time when viewing and editing my GPS data, and I guarantee you'll be more productive once you know them.

1. Every map tool can be selected with a keystroke. Press W to activate the Waypoint tool. Press M to move (pan) the map. Press S to select items on the map.

2. Scroll the map with the numeric keypad (numpad). Press any of the number keys (1-9) on the right side of your keyboard to view the map in that direction. To view the map to the North, press 8. To view the map to the Northeast, press 9. The 5 key (in the middle) takes you back to the Active Point, if you've set one on the map.

3. Zoom the map in and out with + and -.

4. Zoom the map in and out with the scroll wheel on top of your mouse.

5. Make text bigger or smaller (or hide it completely) with [ and ]. I use this constantly to de-clutter the screen. Just press the [ key a few times until all of the text disappears. Use ] to bring it back.

6. Add or remove UTM grid lines with < and >. ExpertGPS chooses the most natural interval between grid lines on the map, but you can add more or remove them completely using these keys.

7. F7 - View in Google Earth. The View in Google Earth command brings up Google Earth's detailed worldwide imagery, perfectly synced to the map and data you're viewing in ExpertGPS.

8. Toggle between Topo Map and Aerial Photo with T and A. I toggle between these two map views constantly, and a single keystroke is all it takes. You can also toggle to Quick Map (Q), Urban Color Imagery (U) and your own Scanned Maps (P).

9. Quickly batch edit your data using F2. Need to change the name of a waypoint? Simply select the waypoint in the Waypoint List by clicking on it with the mouse over the Name column, and press F2 (that's Function Key 2). You can even batch edit multiple waypoints by selecting a bunch of them and using F2 editing.

10. Deselect everything on the map with Esc. Press Esc to clear the map selection, or to finish drawing a route, track, or shape without the Edit dialog appearing.

Related Topics More keyboard shortcuts for ExpertGPS mapping software

Al S. asks:
Will ExpertGPS support USNG coordinates and will it show 1Km grids overlayed onto topo maps as a user selection?

ExpertGPS supports US National Grid (USNG) coordinates. Click Preferences on the File menu. Click on the My Coordinate Formats tab, and click Add. Change the Location to United States, and select US National Grid, NAD83 datum.

You can enter USNG coordinates in the Edit Waypoint dialog, or import them from a CSV file. As you move the cursor over the map, the USNG coordinates for the cursor location are displayed in the lower right corner of the main ExpertGPS window. You can convert lat/lon, UTM, and state plane coordinates to and from USNG by switching between coordinate formats in the My Coordinate Formats dialog.

ExpertGPS displays a kilometer grid when you are viewing USNG, UTM, state plane, or MGRS coordinates. The interval between grid lines is automatically adjusted based on the map scale. At some scales, you'll see a 1KM grid spacing, but as you zoom out the spacing will change to 2KM, 5KM, and 10KM to prevent the map from getting obscured by hundreds of grid lines. You can fine-tune the display of grid lines in the Map Display Options dialog. Or, do what I do, and use the < and > keys to remove or add more grid lines on the fly.

If you want to place a waypoint at every kilometer grid intersection, or create a permanent grid overlay at 1KM intervals, try the new Grid Builder tool in ExpertGPS.

Improving MGRS support in ExpertGPS

Are there ways I can improve the MGRS grid capabilities in ExpertGPS? Post a comment below, or send me an email. I'm always happy to make changes to make ExpertGPS better suit your needs.

Terry F. asks:
We are rural real estate appraisers in Montana. We use Magellan Explorist XLs and have one Magellan Mobile Mapper 6. We want to have the handheld screen to be a topo map that shows Section, Township and Ranges not the usual Long/Lat . Do you have or is there software available that will do that? Thanks.

I don't know of any handheld GPS receiver which can display Section, Township, and Range coordinates instead of latitude and longitude or UTM. However, ExpertGPS Pro now has the ability to display Public Land Survey System (PLSS) coordinates in Township, Section, and Range format. When run on a laptop in your vehicle and attached to a low-cost GPS receiver or GPS "mouse" antenna, ExpertGPS can function as a moving-map display, essentially turning your laptop into a full GPS receiver with a huge screen and full keyboard.

To use ExpertGPS as a moving map display, you'd use the Tracking feature, which polls your GPS receiver or antenna once every second and updates your location on the maps displayed on your laptop's screen.

To go to a specific property, click Go to TRS on the Go menu, and enter the Section, Township, and Range into the Find TRS dialog. ExpertGPS will recenter the map on the property, and create a waypoint marking that location.

If you are in Tracking mode, you can navigate to the parcel by right-clicking the new waypoint and clicking Set Active Point. On the Tracking menu, click Navigate to Active Point.

You can get the TRS coordinates of any point on the map by looking in the lower-right corner of the main ExpertGPS Pro window. In addition to the latitude and longitude, UTM, or state plane coordinates of the cursor position, you'll see the TRS coordinates as well.

Related Topics Additional articles about Section, Township, Range coordinates in ExpertGPS Pro

Daniel W. asks:
I am heading to the middle of nowhere in Utah, and would love to have a way to save some topo maps for offline use. There is no Internet and no mobile phone reception where I'm going, so the normal ExpertGPS "online map" features won't help much.
Otherwise, no complaints. Love your product.

ExpertGPS only needs an Internet connection the first time you view a new area. Every time you view a map in ExpertGPS, it is downloaded from the Internet map server, and stored in a folder on your hard drive. If you disconnect your computer from the Internet and head out into the field, you won't be able to retrieve maps for any new areas, but you'll definitely be able to see topo maps and aerial photos for areas you've already viewed in ExpertGPS.

ExpertGPS has a special tool, designed specifically for downloading maps for an entire area, so you can queue up all of the maps you'll need when you're out in the wild. The Retrieve Maps tool lets you drag a rectangle over the area in Utah you'll be visiting, and you can specify what map scales (1:24K, 1:100K) and map types (topo maps, B/W aerial photos, USGS urban color imagery) you want to pre-load to your hard drive.

I've written a tutorial on copying the entire map folder from your desktop computer to your laptop, which you can follow to copy maps from your main computer to your laptop for your Utah trip. It also discusses turning off the Automatic Map Retrieval in ExpertGPS when your laptop doesn't have an Internet connection.

Have a great trip!

Related Topics ExpertGPS Help File: the Map Retrieval tool How to copy ExpertGPS maps to your laptop computer