GPS Map Accuracy
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 16 years
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I'm new to the group but a long time GPS user. I found your group after I got a Mio C320 for Christmas and was looking for help on importing POIs and using all the other cool features on my new toy. This is a way cool group!
I was able to successfully import POIs that I had created on my laptop-based Garmin GPS-18 with IGO POI Explorer. But I noticed that each address was a couple street numbers off on the C320. I checked and found that the difference in coordinates amounts to about 130 ft. at 40-deg latitude.
So here's the off the wall question - Which coordinates are more accurate, the GPS-18 (City Navigator v8 - Navteq) or the C320 (Tele Atlas N.V.)?
Since I plan on submitting POI files, I'd like to know which map is better. (I don't want to give you the impression that I'm just a complete nerd 
)
Jim Moyer
--
webmaster, www.bma2.org
Chevy or Ford
Which is better, Chevy or Ford? Who really knows. From what I have gathered, over all, Navteq is more accurate. But there are times where telatlas is more accurate, depending where you are.
Charley - Nuvi 350 - Bel STI Driver - Cobra 29 w/ wilson 1000 - AIM: asianfire -
I Agree
I agree! There's no perfect answer. It's like saying which store is cheaper; it all depends on what you're buying. There's no substitute for using all your resources to arrive at the best answer, and even then, there are no guarantees.
Tom
DrWho_100 wrote:
I'm new to the group but a long time GPS user. I found your group after I got a Mio C320 for Christmas and was looking for help on importing POIs and using all the other cool features on my new toy. This is a way cool group!
I was able to successfully import POIs that I had created on my laptop-based Garmin GPS-18 with IGO POI Explorer. But I noticed that each address was a couple street numbers off on the C320. I checked and found that the difference in coordinates amounts to about 130 ft. at 40-deg latitude.
So here's the off the wall question - Which coordinates are more accurate, the GPS-18 (City Navigator v8 - Navteq) or the C320 (Tele Atlas N.V.)?
Since I plan on submitting POI files, I'd like to know which map is better. (I don't want to give you the impression that I'm just a complete nerd
)
Jim Moyer
--
webmaster, www.bma2.org
I have several mapping programs and from My experience using them, one is no better then another. Both on my software and on the online sites my house will always show up a couple of houses east of where it's actually at. Most of the software programs I have show the house numbers on my side of the street going up to 1972 when they actually only go to 1958. I was told the cause of the problem is because the math the mapping companys use figures all city lots as being the same size. I don't know if this is true or not.
Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.
Map Accuracy
I have found that Google Earth is generally very accurate. Another advantage is that you can see the exact location on the map.
pin point a location.
I was told the cause of the problem is because the math the mapping companys use figures all city lots as being the same size. I don't know if this is true or not.
I think it must and give the user a rough guesstimate of where the location is. Several times I have entered addresses and had it be off, on the correct block, but only close to where the location is.
I am not sure if other brands calculate the same way but with Mio if I enter an address it guesstimates where it is and it is usually off. If I try and save that as a PoI it will do a reverse calculation from its incorrect location and give me a different street address.
Map Accuracy
Interesting... Thanks for the comments/opinions.
What I observed is that if I enter coordinates from the Garmin street address in the Mio, it's off by a few house numbers, and vice versa. The difference between the two coordinates is about 130 ft.
Maybe it's math errors between the two, or a small offset in the base maps. To ask the question in another, more practical way: "Which system, Navteq (Garmin and others) or Tele Atlas (Mio and others) is used more widely?
Jim
Mio 320 (+TTS, 2007 maps/12MM POIs) + Jerry Skin(20080213)/ Stopword Hack
House Number Calculations
What I observed is that if I enter coordinates from the Garmin street address in the Mio, it's off by a few house numbers, and vice versa. The difference between the two coordinates is about 130 ft.
None of the maps used on the GPS systems give coordinates for every address. What they do is calculate from the nearest intersection. Each may do the calculation differently and may use different default sizes for the lots.
Putting in an address won't take you to the front door every time, but it will get you close enough to find the correct building.
I plan to live forever. So far, so good.
I agree, a great resource.
I agree, a great resource.
Navteq v. Teleatlas
Here is an in depth look at the two.
http://www.gpsreview.net/navteq-vs-tele-atlas/