How to make your own maps from pictures:

Making custom maps is not the easiest thing in the world, but below is a quick overview of the steps and tools required.

First you will need a DRG (Digital Raster Graphics) map or aerial photo to start from. You can either scan your own paper map, or download a map from one of the USGS Business Partners. My favorite site for quick USGS map sections and aerial photos is Microsoft's TerraServer. It is not the best site if you need to cover a large area. The state of California has all of its USGS maps available for download.  This is a great starting point if you plan to map parts of California. I also highly recommend using USAPhotoMap as an easy way to download large sections of the aerial photos and maps which are available from terraserver. Please see the "reference web sites" section of the USAPhotoMap web site for some good tutorials on using it.

Once you have your map image you will need to use the shareware version of OziExplorer to calibrate your map. The shareware version has a couple of limitations: first you will need to convert the image to a .bmp file using your favorite image editor before OziExplorer can open it. Calibrating the map consists of entering two points on the map of known coordinates.  OziExplorer can then determine where in the world your map belongs.

So where do you find the coordinates of the map? If you downloaded your map from terraserver then there was in info icon which displays the map coordinates. If you got your map from USAPhotoMap then you will notice that the coordinates of the mouse pointer are displayed in the title bar. If you downloaded complete USGS DRG maps then hopefully they still have the coordinates along the edges.

It is important to use the correct map datum when determining the coordinates. The older USGS maps use the NAD27 datum and the newer maps use NAD83. The other limitation of the shareware version of OziExplorer when calibrating maps is that you must use the NAD83 datum. If you have a NAD27 map then you can convert from NAD27 to NAD83 using the jeeep.com coordinate translator.

The picture below shows how I calibrated my maps. The red circles are centered on tic marks which represent the NAD83 coordinates. Fortunately all of the USGS California maps I downloaded have these marks. The coordinates are then entered into the appropriate box. Another way of doing this would be to click on the exact corner of the map and then convert the coordinates to NAD83 and enter 38° 59.995' N 120° 7.5616' W. As you can see the conversion changes by only .005' latitude which is why the red circles are only a little above the corner, but it changes by .0616' longitude which is why the circles are moved much farther in.

Once this is done you can save the map in the OziExplorer .map format.

Now open the map using GPSMapEdit. This little program will allow you to create any streets, trails, and streams. As well as add lakes, forests, and points of interest such as schools, hospitals, campgrounds and so on. Simply trace the elements you want to appear on your map. Be sure to give them the name and description you want to appear on your GPSr. You can also use GPSMapEdit to customize my maps. Use the map properties window to give the map a name, unique ID number, and zoom levels. Use the zoom levels to tell the GPS what to show as you zoom in and out. Links to more information on using GPSMapEdit.

Once you are done making your map, save it and export it into .img format. You can do this from within mapedit but you will need to have downloaded cGpsMapper first.

After you have the .img file, upload it to your GPS using sendmap

This is a brief overview of the steps required to create a custom GPS map. If you think you want to try it then I recommend reading this, this and this for a more step by step guide.