Following are the four steps to scanning your own maps and importing them into the TeleType GPS software. 

1. Scanning

For best results scan an original map, not a copy of the map. If several maps of the area are available, the simpler map will yield the best results. (Too much background detail makes a map difficult to see on the screen of your HPC.) The scale of the map does not matter, since the GPS software will zoom in or out as necessary.

• Position your map such that north will appear at the top of the scanned image. It is very important for navigation that the map is oriented precisely.

• You may scan the map at any resolution you desire, but, for ease of use, multiples of 72 dpi work best (i.e. 72, 144, 216, etc.). Note that a higher resolution scan will result in a larger file.  In some cases you may find that a map scanned at over 144dpi simply won't fit on your HPC.

• To keep file size down, you may wish to crop out areas of the map that are unimportant to you. For example, if you want to scan in a map of New York, but your map also features New Jersey, cut or crop New Jersey out of the scanned image to reduce file size.

• Some graphics software will allow you to modify your scanned map to make viewing it on your HPC easier.  If you have access to software like Adobe Photoshop, you can sharpen or increase the contrast of the scanned image, improving the clarity of the map on your HPC.

• When you are happy with the quality of your map, save it as a .bmp file.

2. Locating the Map Center

Open the .bmp file using Microsoft Paint or any other graphics software.  Draw two diagonal lines connecting opposite corners of the image.  The center of the map is at the intersection of the lines. Identify the latitude and longitude of the center of the map.  Be as accurate as possible, but do not worry if you cannot find exact figures. You can adjust this location after the map is placed into the handheld PC.

3. Creating the Associated Text File

Create a new text file on your PC or using Microsoft Word on your HPC.  This will contain the information necessary for the GPS software to interpret your scanned map.

     Type the line below into the text file, exactly as shown, including letters, brackets and vertical bars. (Note: there is no vertical line between the last number of the LS figure and the end bracket):

<|LT:42.38167|LN:-71.09969|LS:15676>

Where:

LT value specifies map-center latitude in fraction of degrees.
(Latitudes south of the equator are noted by a minus sign)

LN value specifies map-center longitude in fraction of degrees.
(Longitudes west of the prime meridian are noted by a minus sign)

LS is a calculated value.

To obtain the LS value you need the following:

A. The number of inches that the physical scale bar on the map occupies (BAR). You can measure just a part of the scale bar if this is easier; just be sure to remember what part you measured.

For example, open the .bmp file in Microsoft Paint. If the scale bar on the map is broken into 0.5-mile divisions, you can measure just one of the divisions on the screen of your desktop PC. If, for instance, the division you measured is 3 inches long, then your BAR is 3 inches.

B. The scale length of the section of the scale bar you measured, in miles (DIST). This can be the total on the bar or just one division, whichever you measured in step A. (Note: Metric measurements on maps must be converted to miles. You can do this easily with a conversion program such as "E-Converter."  This freeware program by Eric Francois (eric.francois@bigfoot.com) is available at http://www2.vo.lu/homepages/efrancois.)

C. LS in English System = DIST/(BAR * 0.000015855408)

Example:
DIST = 0.5 miles
BAR = 3 inches

Therefore:
LS=0.5/3 * 0.000015855408 = 10511.66

Be sure, once you have entered these three values that you save the text file to match the name of your .bmp file.  If you scanned a map of London, and saved the graphic image as london.bmp, then be sure to name your text file london.htm

4. Importing the Map into the TeleType GPS program

Create a folder anywhere on the hand held PC called London, and place both the .bmp and the .htm file you created into that folder. (Alternatively, you can create the folder on the desktop computer and copy the whole folder to any location on the HPC).

• Select "Load Map" from the TeleType GPS File menu.
• Select File Type as Images File (*.bmp,...).
• Select the .bmp file to import.

The scanned map will appear on your navigation screen when you zoom in sufficiently.

Example:

This example (Melb.zip) includes two files Melb.htm and Melb.bmp. You can download this zip file to view the .bmp map on TeleType GPS program.   

 

Checking Your Scanned Map For Accuracy

t is very important to check your accuracy when scanning a map. If your map is not reasonably accurate, you could find yourself some distance from where you really want to be.

Making those important adjustments is simply a matter of tweaking your .htm or text file to make everything lie where it should.

First you must check the scale of your scanned map. The easiest way to do this is to measure the straight-line distance between two easily recognizable points on the paper map. Now, open the scanned map in the GPS software. While holding down the Ctrl button, tap once on each of the two points you measured on your original paper map.

If your scanned map is scaled correctly, the distances should match up. Otherwise, it is simply a matter of editing the LS figure until the scales match. Increase or decrease the value repeatedly in small increments, modifying LS in the direction that causes the scales to be closer.

Once your scale is correct, you must verify that your center point is accurate. Find your position on the paper map. Then, connect your GPS receiver to your HPC, and turn it on.  Your position will be marked on the scanned map in the GPS program. Your position on your HPC will coincide with your position on the paper map if the map center is correct. Otherwise, you must modify the LT and LN values as detailed for LS, above, until your position is correctly shown.

To test your map’s accuracy now, plug your GPS receiver into your HPC, and go for a walk, ride your bike, or hop in the car.  If the track displaying on the HPC matches the route you are taking, your scanned map is accurate. Otherwise, you must recalibrate the .htm file until everything is working well.

Note: None of these adjustments are necessary if your original calculations are correct. Take the time to perform them accurately and double-check your answers to avoid any problems.