GPS is wacky
I have been getting some weird directions from my Garmin Gps since we have been in Canada and Alaska. Today it took me to the back woods and when I got turned around and found my way to a campground ...
Forum Discussion
The answer to your problem is very simple and I have had to deal with it for years.
Cartographers (map makers) have to work from survey data reported to them be field teams. There is a very simple problem there. Until the advent of price electronic navigation, finding your actual location on the globe took a lot of hard work. The U.S.A. has always been careful about this, but there are still lots of fun stories. (Look up Isle Royale.)
It happens that the Canadian surveys were never all that good and great care had to be used when counting on their published marine charts. They are getting better. So, when traveling by land in Canada, the GPS location and the published map may disagree, but the lat/long provided by the GPS is probably correct. The map data supplier to the program builder was probably in error. The error may be consistent, or it may not.....
Along the Alaskan coast, my GPS agreed with the USCGS charts, but once inland there were problems. With the population of Alaska, there was no real interest in creating high accuracy maps for drivers. Much of the area of Alaska has bee re-mapped with overflight and satellite data and I am told that it is now pretty good.
Matt
Cartographers (map makers) have to work from survey data reported to them be field teams. There is a very simple problem there. Until the advent of price electronic navigation, finding your actual location on the globe took a lot of hard work. The U.S.A. has always been careful about this, but there are still lots of fun stories. (Look up Isle Royale.)
It happens that the Canadian surveys were never all that good and great care had to be used when counting on their published marine charts. They are getting better. So, when traveling by land in Canada, the GPS location and the published map may disagree, but the lat/long provided by the GPS is probably correct. The map data supplier to the program builder was probably in error. The error may be consistent, or it may not.....
Along the Alaskan coast, my GPS agreed with the USCGS charts, but once inland there were problems. With the population of Alaska, there was no real interest in creating high accuracy maps for drivers. Much of the area of Alaska has bee re-mapped with overflight and satellite data and I am told that it is now pretty good.
Matt
