POIs off

[wfin73]

I just got a new 140s last week, updated the map (with much difficulty), etc. I took it for my first trip this weekend, and it worked great, with one minor exception. It seems all my POIs are off by about an 1/8th of a mile. I was sitting at a red light last night at an intersection and there was a restaurant to my immediate right. My TT showed it in the middle of the road, about 1/8th of a mile ahead on the map. After that, I paid closer attention, and they all seemed to be off consistantly about the same distance on the map vs. true position. Everything else is right on street wise, just the POIs are off, what would cause this? It's not a huge deal, but with my wife's older TT One, they are right where they are supposed to be.

 

[dervari]

POIs are not an exact science, because in the mapping world street addresses aren't. Most maps will take a street along with the known starting and ending adress numbers along the street. Then, they will average out where each address should be on the street. Since the POI database knows the address should be 2134 Main St, it will use the guestimated location of where number 2134 is on Main St.

I have never seen a perfect door to door GPS unless you use a lat/lon to mark your destination. Anyone expecting such accuracy out of a GPS unit with consumer grade maps (ie inexpensive) is in for a shock.

 

[wfin73]

I agree that it's not an exact science, I know for $150 it's not going to be perfect. But my wifes nearly 3 year old TT One is much more accurate, the POI's show up right where they should be. Like I said, mine is nearly 1/8th of a mile off consistently, which seems unusual to be that far off every time.

 

[spook45]

The inaccuracy goes across different mfg's....

Over the last two years I have used a Garmin 660, Magellan 4040 and HP iPAQ 310. They all have the same results. My house location shows just right on each map of the different GPS's but when you check the address it will be off by about 3 houses. If I set the GPS's to go to a specific address they all will be off by the same amount (abouit three houses or about 500 feet) and always in the same direction (Due west).

I have concluded that this is just a map thing. All the units I've used have had Navteq maps. I am thinking of getting a TT 730T and I find it interesting that the same map flaw exisits in both Mapping Companies, Navteq and TeleAtlas.