Maps,Navigation and GPS

Not really a fishing topic this, but one about something that I find useful when travelling to a new venue.

I’ve already written on a couple of occasions about GPS units and how much I like them as navigational aids in France. In fact I’ve used the Tomtom One now for a number of years and would be lost without it. Most of the units on the market are of the street navigator type, which are perfect for getting from A to B and finding ones way around a city, but they give very little  or no information about the type of terrain one is on and many don’t have any info at all on lakes, tracks to lakes etc. For this an Ordinance Survey topographical map is the best tool.

Now topographical GPS devices do exit also, aimed at hikers and offroaders they are like an electronic geo-referenced Ordinance Survey map. They give you your exact position and allow you to install very detailed maps of your chosen area. But, and this is a big BUT, they are extremely dear for the best ones. The Garmin Dakota 20 or Twonav Aventura are in the 400-600€ bracket and that is without the 25:000 scale  maps that cost over 100€ each. This for me was a real deal breaker…I just can’t afford that amount on a gadget.
However recently I have found a great plugin on a French GPS site that allows you to turn your Tomtom into a great off road/fishing tool. The plugin is called “ttmaps”.

This excellent tool, allows you to display detailed ‘raster’ topographical maps on your Tomtom device. It is simple to install and you can even download a few large scaled maps of France and Europe to see how it works.
But the real interest is to create your own detailed maps from sites like ‘Multimap’  (for Ordinance Survey in the UK) Geoportail.fr (for IGN maps in France)…and even Google Earth if you want satelite photos in your GPS.
To make up your own maps I have to admit is a little time consuming and somewhat complex, but it is fun and not really that hard. For me though the finished result is really worth the effort of getting your head around the mapping method.

Once installed you’ll find the ttmaps button in your Tomtom menus. Click on it and you’ll be in the ttmaps mode. It will follow your movements as a regular GPS but your background will be YOUR map. Note that you won’t be able to set routes to navigate like the street pilot mode, but instead navigate by the bearing.
It will allow you to show a certain amount of information to help you use it with a map ie. your UTM position for the more advanced users who make use of the functions with an Ordinance Survey or IGN map. You’ll really need to check the authors site to get all the user info to get the best from the plugin.“ttmaps

How to Create your own Maps

As I said above, the real use of this tool is to create your own maps of your chosen venue. Imagine a detailed OS map of the Orient or St Cassien, with all the tracks and contours. You can even scan your own maps onto your PC and convert them to be read on your Tomtom.

You will need a few free to download pieces of software and a photo editing tool like Photoshop. The final file needs to be geo-referenced and saved as a .ecw document.

Here’s a list of the tools you need:

  1. Ozi Explorer (Limited version Free to use)
  2. Create ECW Note: this software is in French, but only needs one or two clicks to save out the map.

I make a map in a few easy steps.

  1. I find the area I want in say Multimap or Geoportail.fr in France. I enlarge it to get as much detail as I want usually around 1/25,000 ie: tracks, forests, lakes etc. With all the contours and features.
  2. I then copy the screen and paste it into a blank Photoshop document. You can use this copy/paste technique to paste up as many screen shots as you wish to cover as wide an area as you wish. I’ve added upto 50 to cover all of Wales for example. But you can just do a few to cover your area, or a French lake like the Orient or you can scan a map onto your computer. Save this document as a bitmap file.
  3. Open up the Ozi Explorer demo and import your .bmp file as ‘Load and Calibrate map image’.
    You need to get two Lon/Lat readings from Google Earth for example, so you can add these to the Ozi Explorer info ‘Points 1 & 2 on the right hand window. (Note the trial version only allows you to enter two points but it’s enough to calibrate your map). One from the top left hand side of the map and one from the bottom right hand corner. These will need to be obvious features on the map, crossroads or major junction for example
  4. Save this document which will produce a .map file.
  5. Launch Create ECW: Select your .map file in the first window (Selectionner)
  6. Search for where you want to output your file : Parcourir
  7. Datum Destination :WGS84/Spherical Mercator
  8. Compression: 90
  9. Then hit : Commence Conversion -> you will end up with a .ECW file you can upload to your Tomtom from your PC into the MAPS folder in ttmaps

Many of you may find all this very complex and too much trouble, so really it’s more for the geeky, techno junkies like myself. But it can be of use for your foreign fishing trips as it can give you detailed info on access routes to waters which definitely won’t be on your regular sat nav maps. If you are looking for that exact swim to track to an area it can prove difficult to find on waters such as the Orient or the Der. I’ve fished the Orient a number of times and the routes to places like Geraudot bay or Michelin point can be hard to find. But by combining tools like Google Earth with your own maps, once on the ground you can pin point the access roads easily.

Finally you can download or create your own routes in the GPX format that Garmin and other topographincel GPS devices use. A site like http://www.marengo-ltd.com/map/ lets you save out a route in GPX that you can upload to your Tomtom.

Have fun…

Cheers
Gareth

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2 Responses to Maps,Navigation and GPS

  1. croixblanche says:

    I forgot, before installing ttmaps on a Tomtom device, make sure you back up your GPS on Tomtom Home.
    Cheers
    Gareth

  2. croixblanche says:

    I forgot, before installing ttmaps on a Tomtom device, make sure you back up your GPS on Tomtom Home.
    Cheers
    Gareth

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