I beleive the original version of gpsmapper (0085 ver. ?) could convert a garmin .img file into a MP (Polish Format) file. Using "MapEdit" you could edit the .MP file, add roads etc., and then convert back to a Garmin .img file. The newer version of gpsmapper will not do this conversion, I assume owing to copyright liabilities.
I have used gpsmapper to make my own maps, the only reason for doing so is to create maps with much, much more detail than Garmins. The process is time consuming, and was originally developed for gps enthusiasts in foreign countries where Garmin didn't offer map coverage. The down-side of having more detailed maps is that the files are obviously larger than a typical Garmin file. The up-side is that it is very satisfying to be on your favorite lake following a shoreline and having the gps track follow the shoreline to a T. With Garmin topo, I would frequently find myself tracking "way up" on dry land.
My first map was of Lows Lake in the Adirondacks....Garmin topo is horrible compared to what you can do tracing a standard 1:24K USGS Quad map. Garmin topo eliminated many of the smaller islands, had irregular and "odd" shapes for many of the larger islands, and just plain left out several Kayak/canoe passages altogether.
I would suggest making your own maps for one or several of your favorite areas, but as an alternative to the Garmin maps, it's just simply too much work compared to the ease of buying the available Garmin product. I would also add that although I'm not thrilled with the detail of the Garmin topo, it would be impractical to have all my maps in higher detail. If I did, I would probably only be able to fit a few ny counties in the unit at a time.
Almost forgot the original question.....no, it cannot be easily done, at least not the first time you do it. Once you have gone thru the process , the next map is much mcuh easier.
Hi could you briefly write out the process in point form?
