Eugenijus K. needs help calibrating a map of Lithuania, and overlaying a grid in Lietuvos Koordinaciu Sistema (LKS94), the Lithuanian national coordinate system. Here's how to do it using ExpertGPS:

Looking at this map of Lithuania, I can tell that it uses an equirectangular (lat/lon) projection, rather than the Lithuanian Transverse Mercator grid (LKS94). This is because the top left and bottom left corners have the same longitude (20 degrees East), and the top right and bottom right corners are the same as well (27 degrees, 30 minutes East longitude).

To get started, I created a waypoint and recented the Quick Map view in ExpertGPS on Vilnius, Lithuania. I always like to start calibrating a map with some data from the location the map covers. I did a search on Bing.com and quickly found the latitude and longitude of Vilnius, and created a waypoint with those coordinates.

To add the map to ExpertGPS, I clicked Open Scanned Map Library on the Map menu, and then clicked Add. I selected the .jpg file with the map image, and then entered the name of the map, and the projection it uses (Equirectangular).

Calibrating the map

I used three calibration points to calibrate this map. I always try to place the first point in the upper left corner, in this case, at 57 degrees North, 20 degrees West. I placed the second calibration point in the opposite corner, at 53N, 27 deg, 30 min W. Two points are usually enough to properly calibrate a map, and as soon as I added the second point, my waypoint for Vilnius appeared at the correct location on the map. If a third calibration point is required, I try to pick one of the remaining corners, in this case, the lower left one.

Adding the Grid Overlay

To add the Lithunia LKS 1994 grid, I followed these instructions for adding a new coordinate format to ExpertGPS, and selected the LKS grid as shown below.

As soon as I switched to this coordinate format, the grid lines in ExpertGPS switched from showing latitude and longitude to showing eastings and northings in Lithuania's national grid. As you can see in the image below, the grid is centered on 24 degrees East longitude, which runs directly through the center of the country. Because the underlying map is still using an equirectangular projection, the grid lines to the left of the central meridian (24E) curve one direction, and the lines on the right curve in the opposite direction.

Learn More about Scanned Maps in ExpertGPS

To learn more about using your scanned or digital maps with ExpertGPS, read the Scanned Maps tutorials on this site, or Ask the GPS Expert if you need help getting your maps properly aligned in ExpertGPS.

Mike G. uses ExpertGPS to research abandoned railroads in Northeast Pennsylvania. Here he reviews ExpertGPS as a historical map research tool:

The main reason why I tried out this program, and purchased it, is because one of my hobbies is abandoned railroad research. My area has a large network of abandoned railroads since at one time the coal industry was "king".

Looking at present day Topo maps and even ariels are limited because most of the old ROW's have been erased or are broken up by development. There is a site that has historical USGS maps which is very helpful to trace out these once busy lines, but is limited. The single most reason I purchased this program was the ability to take a historical USGS maps and integrate them and make them more GPS accurate. Already there are a few relics from a former railroad line that could not be identified until I overlayed the map onto my GPS data. I maintain a website with my findings and the example of how this program solved a mystery can be found here.

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.

Monica writes:
I was wondering about a state correction for NAD 83 in New Mexico. I am not from here, but have an airphoto that I am working with in this specific system. My GPS unit does not have this grid installed. Would you suggest that I purchase a different GPS unit, or should I have this particular map converted? Are all maps likely going to be in this "State specific" grid system?

You're not going to find a consumer-grade GPS receiver that supports New Mexico state plane coordinates, or any of the other US state plane coordinate systems. Garmin and Magellan simply don't include these professional coordinate systems on their consumer-grade GPS receivers.

The easiest way to convert NM SPCS to something your GPS can use (lat/lon, or UTM) is to use mapping software like ExpertGPS Pro. ExpertGPS will allow you to work with New Mexico state plane coordinates and calibrate your airphoto using state plane coordinates. You can then switch the coordinate format in ExpertGPS to latitude/longitude or UTM, to match your GPS. This makes it very easy to convert between state plane and UTM or latitude/longitude GPS coordinates.

Even when you're viewing a map or aerial orthophoto projected using the New Mexico state plane coordinate system, ExpertGPS Pro will be able to convert your GPS data (waypoints, routes, and tracks) back and forth between NM SPCS NAD83 and whatever format your GPS uses (lat/lon NAD27, UTM WGS84, etc) so that your data always displays in the correct location.

To get started with ExpertGPS, download the 30-day trial and follow these instructions for calibrating and geo-referencing your NM NAD83 airphoto.

Mark H. asks:
I simply love using ExpertGPS software to look at areas before I go, and download gps data after I have been. It is simply great.
Lately I have been looking for topo maps that may be older than what displays. Primary purpose; to view and mark waypoints on terrain before it was flooded and became a lake. I am wanting to find contours on Lake Fork Reservoir before it was flooded. I can see this currently, but as I zoom in the images are after it became a reservoir. How can I zoom in on this area prior to flooding? Thank you.

You can display historical topo maps in ExpertGPS using the Scanned Maps feature. After you've found and downloaded an old topo map, you can use ExpertGPS to calibrate it so that your GPS data will appear over it in the correct location.

ExpertGPS lets you switch back and forth between your scanned historical maps and the modern-day USGS topographic maps and aerial photos for that same location. You can mark modern features as waypoints or draw directly on the map to trace old railroad rights-of-way, and then see exactly where they lie on the modern maps and aerial imagery. If you're a history buff, like researching abandoned railroads, or want to find old farmsteads or house foundations, ExpertGPS can be a huge help in your historical research.

Finding Historical Topo Maps

Try some of these great sites for old US topo maps, or use Google to search for maps for your area

Historical Topo Maps at Maptech.com

Historical Topo Maps of New England and New York

Historical Topo Maps of California

Historical US Maps at the Perry-Castañeda Library - this site is my favorite resource for scanned maps of all types.

Have a source for Historical Topo Maps that I've failed to mention? Add a comment below!

Related Topics Calibrating Scanned Topo Maps More tutorials on using Scanned Maps in ExpertGPS

Bill G. asks:
I see that I can enter my hunting areas with expert GPS and did see some farm capabilities. How easy is it to put fence lines and gates on the maps? Can I pull in a Google Earth image and draw directly on that? Can I add and remove layers? example, maybe I don't want to see the deer trails, can I hide them and then view them again later? Thanks for your help!

It's as easy as pointing and clicking. You can trace fence lines directly off the aerial imagery of your fields. ExpertGPS does have a Layers feature, but even easier is to simply hide the data you want to temporarily remove from the map. Select the data, right-click, and Hide. When you want to see it all again, click Show All on the Edit menu.

The View in Google Earth command in ExpertGPS allows you to view your GPS data (waypoints, routes, and tracks) over the detailed color imagery in Google Earth. To use the command, open a GPX file in ExpertGPS, or retrieve the data from your GPS. Press F7, or click View in Google Earth on the View menu. ExpertGPS will instruct Google Earth to synchronize its map to match the map in ExpertGPS, and to show your GPS data.

If Google Earth is not already running when you click View in Google Earth, it may not show your data because it is busy initializing. To prevent this, run Google Earth and let it finish initializing and zoom in on the globe. Then click View in Google Earth in ExpertGPS.

You can also export your data from ExpertGPS to a KML file, which you can then view in Google Earth. Click on the map in ExpertGPS, and then click Export Data on Map on the File menu. Change the file type to .kml, and save to your desktop. Open the KML file in Google Earth.

ExpertGPS cannot display Google Earth's worldwide color imagery directly. Google's terms of use forbid this. You can, however, export an image from Google Earth and use it as a Scanned Map in ExpertGPS.

The ExpertGPS help file has complete details about preparing and geo-referencing your maps for use within the program.

Related Topics Adding a Google Earth image to ExpertGPS

Warren H. asks:
I have just purchased ExpertGPS Pro with GIS support. I would like to add some of the orthophotos I use in Arcview to this program. I have world files for these images. I know I can manually "calibrate" the images, but that is not nearly as accurate as the information from the world file. Is there any way to manually enter the information from the world file to calibrate the image, or do I have to estimate points by selecting a point and assigning a lat/lon to the point?

How to Import Orthophotos with a World File into ExpertGPS Pro

ExpertGPS Pro will read the worldfile accompanying your orthophoto and extract the geo-referencing information from it. All you have to do is change the File Type selector in the Add Scanned Map dialog, so that you can select the World File rather than the image itself.

Click Open Scanned Map Library on the Map menu, and then click the Add button. This will bring up a "browse for file" dialog where you can select the image to import. At the bottom of this dialog is a file type selection drop-down list, which by default is set to select the image file itself (.jpg, .tif, .png, .bmp). Change this selection to World File (.jgw, .tfw, .pgw, .bpw) and now you can select the World File that accompanies your image.

ExpertGPS will do the rest. All you have to do is click the Edit button in the Scanned Map Library, and select the correct projection and datum. ExpertGPS Pro has already imported all of the geo-referencing data from the worldfile.

Related Topics
ExpertGPS Help File: Add Scanned Map command

Keith S. asks:
Hi Dan, I'm off to Mongolia in a few days and was searching for some maps when I found this great site at the University of Texas. They are Lambert Conformal and state the standard parallells. I gather from searching the forum that I guess the left or right edge as the central meridian. I'm hooped when it comes to Origin Latitude and False Easting and Northing. Can you help? The Mongolia map is here

How to use a Lambert Conformal Conic Map in ExpertGPS?

The Standard Parallels for your map (44° 20'N and 47° 20'N) are listed on the map collar underneath the map. The Central Meridian isn't given, but there are two easy ways to determine it. For almost every map you'll ever encounter, the central meridian runs vertically down the center of the map. Look for a line of longitude that is perfectly vertical - parallel to the left and right edges of the map sheet. If you look at the lines of longitude on your map, 102°E (on the left side) leans in to the right, and 108°E (on the right side) leans in to the left. 105°E is perfectly vertical - that's your Central Meridian. Note that the map is centered on this line, and that 105° is halfway between 102° and 108°, the two outer bounds of longitude. For most of the maps you encounter, taking the average of those two extremes of longitude will get you to the Central Meridian.

You can safely ignore the remaining parameters: Origin Latitude, False Easting, and False Northing. Just set them to zero. These three parameters are used (along with Units) on some maps to define another geographic coordinate system based on the Lambert projection. For example, in my home state of Massachusetts, many GIS maps are based on the Massachusetts Mainland State Plane Coordinate System, which is an X,Y coordinate grid that is used instead of latitudes and longitudes. The Origin Latitude, False Easting, and False Northing are parameters used by the equation that transforms latitude and longitude coordinates into rectangular X, Y coordinates in the MA SPCS. These parameters are provided for ExpertGPS Pro users who are importing pre-calibrated maps that come with an accompanying worldfile. Worldfile coordinates are specified in X,Y rather than lat/lon, so ExpertGPS needs to know all of the parameters in the equation described above. For maps in one of the US State Plane Coordinate System formats, ExpertGPS has all of the parameters built-in, you just need to select the correct State Plane coordinate format. I've only had to enter the full set of Lambert projection parameters twice, both times for importing scanned maps that show all 50 US states or the 48 continental ones. For these maps, a Lambert or Albers Equal Area projection is commonly used. Contact me if you need help importing such a map.

The correctly-calibrated map of Ulaan Baatar, Mongolia, is shown above. Three calibration points were added at the upper left, lower right, and lower left. The latitude and longitude lines drawn by ExpertGPS match up exactly with the lines on the map, confirming that the map is calibrated correctly.

Related Topics
ExpertGPS Help File: Calibrating a Scanned Map Image
University of Texas Perry-Castañeda Map Collection - a great source of scanned maps for many nations

Russell T asks:
The District is considering the purchase of a new GEOTIFF aerial image of the district boundaries for mapping of the infrastructure...the consultant we have been in contact with is advising us to purchase the image in this format for its exceptional horizontal accuracy.
My question to you is does ExpertGPS software support the beforementioned format and or if there is a better format to employ in your opinion.
As a backup thought I have requested we receive the image in various formats to make sure all of our software would be compatible with it....
Last but not least...when importing an image to ExpertGPS what format would yield the absolute best accuracy we could hope for?

How to use GeoTIFF imagery in ExpertGPS?

ExpertGPS doesn't have the ability to read the projection and georeferencing data out of a GeoTIFF at this time, although it's high on my list of to-do features for GIS users. ExpertGPS will treat it as an uncalibrated TIFF, meaning you'll have to do the calibration by hand. It should be relatively painless for the consultant or the imagery provider to also provide a .tfw calibration file with the GeoTIFF - this would be standard if they were providing imagery for use in ArcGIS, so they should be used to it. If they don't, there are free programs to extract a .tfw from the GeoTIFF. The accuracy you get in ExpertGPS depends on the quality of the ortho-rectification done by the imagery provider and the correctness of the calibration points (tie points) given in the GeoTIFF or .tfw worldfile. Overhead imagery needs to be ortho-rectified by the imagery provider to remove the distortion caused by the aerial camera not pointing straight down when the photo is taken. They will also add the georeferencing data, the calibration points that allow ExpertGPS to determine the latitude and longitude of every pixel on the image. Your contract with the imagery provider should specify the level of accuracy to expect across the entire image. Orthoimages are large files, and you may receive a file that has been compressed to reduce its file size. One drawback of image compression, especially the wavelet compression used by MrSID imagery, is that it can produce ringing artifacts around the edges of features. This can make it difficult to precisely locate features on the map, since edges may spread out over several pixels. Ask for an uncompressed or lossless image in addition to any lossy, compressed images they provide. Related Topics ExpertGPS Help File: Calibrating a Scanned Map Image TopoGrafix User Forums: Extracting GeoTIFF Worldfiles]]> http://blog.expertgps.com/blog/2008/10/using-geotiff-maps-in-expertgps/feed/ 0