Topo map and GPS position do not match

I have a GPSMAP 62ST with the preloaded 100k US topo map. My position on the topo map is about 500m displaced from where I actually am. Similarly, if I record a track and load it into Basecamp the track is displaced on the map, but if I export the track to another map program the track matches the other map perfectly. Also, the GPS coordinate of any waypoint match the other map perfectly.

So I'm getting good GSP coordinates but the alignment with the map is off. I've tried resetting the map with the blue triangle in the top left corner but nothing changes.

Has anyone got any ideas what I can do?

0 Former Member over 12 years ago

You will find SELDOM's maps at GPSFileDepot and will also find mine there. However you really can't make general statements like "they are much better than the Garmin 100k maps". The GPSFileDepot maps are created by many different people with various levels of ability using different techniques with different data sources and different goals.

Some may be better than the Garmin 100k, others may be worse. In fact, the same inaccurate road data from the US Census Bureau (TIGER Shapefiles) was used by Garmin as well as most of the map authors at GPSFileDepot.

There are other differences as well. For example, it will generally be awkward to use the maps from GPSFileDepot across state borders as there is no standard on the boundaries that different authors use in their maps. Therefore you may find blank areas where mapsets from two authors overlap. OTOH, Garmin's 100k topo is seamless.

The Garmin 100k topo also includes DEM data (Digital Elevation Model). This can be useful for creating elevation profiles for routes and tracks and it provides shaded terrain on newer Garmin handhelds and 3d views in Basecamp. None of the maps at GPSFileDepot contain DEM data as there are no third party tools available to create it in Garmin's format.

Obviously I am a fan of GPSFileDepot or I wouldn't upload my own work there. But there are some differences you should be aware of, and you really can't make blanket statements about the quality of third party maps.

-Boyd