offset tracks

The only way to ensure that tracks or routes follow the same path is to use the exact same map version. If your friend was using anything other than the exact map you are using, all bets are off.

-dan

I don't understand that, tracks are tracks and waypoints are waypoints? If you use a different system or not, the notation is different, but it will be still the same point? Or am I seeing ghosts?

While you are correct that a waypoint does not change its location on a latitude/longitude grid no matter what map it is displayed on, the "picture" of the real word which is drawn on those maps can vary quite a bit.

So if a waypoint at location X,Y on your friend's map is dead center on Main Street, that waypoint will appear on your different map also precisely at position X,Y, but the road may be depicted 200 pixels to the right, making it appear to no longer be on Main Street at all. Take your GPS to that location and read your position and you may be surprised to find that neither map is 100% accurate in how it draws Main Street.

You can test this on your map by zooming way in and out. The waypoint does not move, but the way the road is drawn can change so much that the waypoint is no longer on it. This is why all on-road GPSes use rubber-banding to show your car icon traveling on a road. Without rubber-banding, your icon would wander off into nearby fields, ditches, parking lots or even onto parallel roads -- the whole time showing your actual, accurate position, but failing to sync with the picture on your screen.

The real-world location has not changed; the graphic simulation of the real world does indeed change between versions. Having planned routes turn-by-turn across the entire US, and having to coordinate between several map sources (Garmin, Google, MapQuest) and versions within those sources, I can tell you that this is true and can have enormous effects on routing.

-dan

So, in my case, if I want to have those tracks in the right position, is there any way to correct those? There should be right, it is just a mathematical error correction? How would I go about it?

It depends what you want to do with it. After all, per your first reply, you correctly note that a track is a track, so its lat/long coordinates are correct if it was created by tracking an actual ride your friend took. In that case, if all you want to know is where he went, do nothing; it's one (or both) of the maps that is wrong, not the track.

If however you want to go duplicate that ride, turn the track into a route using BaseCamp and then edit the route to fit YOUR map so that your GPS will give you the correct directions. Save it as a route and transfer it to your GPS.

At that point it will no longer be your friend's track, but it will follow the roads or paths shown on your GPS.

There's no correction factor you can use because there's no practical way to know which map is off and by how much. At any given spot the road drawn on your map may be east, west, north or south of his track coordinates. And that all can change between there and the next waypoint. Put another way, your GPS can't rubber-band a track to fit its roads, but it can do that quite well with a route.

So, starting with the track, which you know to be correct, plan a new route that mimics it as closely as possible using your own map and you'll be good to go.

-dan

Okay, here you can see the OSM World map of Suriname. Now some sections of Suriname are not mapped yet, so that is why it looks a bit strange. But you can clearly see that my tracks fall within the OSM roads and my friends tracks not.

Now the thing is, that I am interested in my friends tracks that cover the open savanna and jungle trails. But they all have the same offset.

Somehow I want to use a general outline of the tracks to orientate myself. So my first question is can I correct the offset somehow?

Adventurous greetings,
Coen

Interesting.

How about if you send him one of your tracks and get him to report if it lines up with his map or is offset the other direction?

-dan

One other suggestion, with that much offset, I would suggest your friend recalibrate his map in TrackMaker. Give him a few (six) waypoints of prominent features around a large area of the maps you are using (OSM?).

He can use those waypoints to recalibrate his map. Then the Tracks he draws will at least be close to the maps you are using.

If he is not willing to do that, ask if he can save his Tracks as images (JPG, TIFF, PNG, BMP). If he can then use that image of his tracks to create a Garmin CustomMap which you can load into BaseCamp and your GPS if it supports them.

Cheers,

One other thing you might try if TrackMaker supports them is having your friend save his Track as GPX so you can import them directly into BaseCamp v3.2.2. If you have BaseCamp v3.3.0.1 beta installed he can save them as KML/KMZ. Then you can import them directly into BaseCamp-beta.

This just removes the conversation in GPSBabel.

Cheers,

This image shows the .kml flle that has been converted from the .gtm [trackmaker] by GPSBabel. This also shows the offset.

Now, my friend is actually a group of 4x4 enthousiasts that have been collecting tracks for the last few years. And I am not sure who is in command of the maps and stuff, this trackmaker file is roaming around the community so to speak.

I was happy to see that I could convert the map using GPSBabel and that it would actually load into Google Earth and BaseCamp. Then I saw the offset and I thought there must be a simple solution to shift all the points. But I can't find a way to do with the means that I have in front of me...

The 60csx doesn't allow custom maps, so I am not helped by that.

First I want to tackle the offset so that the tracks correspond with the BaseCamp I have. Step two is getting those tracks into vectors so I can load it as a map into the 60. Because there is way to much data to transfer them as tracks [with the limitation of the gps]

Adventurous greetings,
Coen