POI accuracy?

 

I recently used 4 POI files on a trip to Kentucky and was distressed to find that several of the locations were unusable and about half were marginally useful.

By the third day, we just entered the address and ignored the POI files I had downloaded.

COnverting an address to a Lat/Long should not be acceptable. The GPS does this just fine by itself. In one case, the POI was located on a highway miles from the actual location. When we gave up and called, we were told that the address was outside the database on all GPS units. This tells me the POI preparer took a few shortcuts.

Many tourist destinations have driveways or access roads and one would naturally expect an accurate location to be in front of the visitor center or in the parking lot. On the street, in front of the location should only be acceptable for storefronts.

I will be submitting corrections later this week but I did want some feedback. Am I asking too much? Perhaps this issue can be resolved with a comment line on the file indicating whether the data was field checked or converted from address data.

Specific examples on request.

Both sides

I see both sides. I have worked on files that only have a few locations. There are other files that have thousands.

When I am working on a file that has locations in an area that I am not familiar with, and then can't get a good visual from the sky to confirm (photo) then I try and add a comment. The problem is that most company web sites offer little assistance. The X is not close to the store at all.

I then rely on feedback for the file to correct errors I don't catch. And you will find that there are some areas that the addresses gps wise don't map right at all.

Daniel

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Garmin StreetPilot c580 & Nuvi 760 - Member 32160 - Traveling in Kansas

You can check this yourself

alagave1 wrote:

I recently used 4 POI files on a trip to Kentucky and was distressed to find that several of the locations were unusable and about half were marginally useful.

By the third day, we just entered the address and ignored the POI files I had downloaded.

This tells me the POI preparer took a few shortcuts.

Many tourist destinations have driveways or access roads and one would naturally expect an accurate location to be in front of the visitor center or in the parking lot. On the street, in front of the location should only be acceptable for storefronts.

I will be submitting corrections later this week but I did want some feedback. Am I asking too much? Perhaps this issue can be resolved with a comment line on the file indicating whether the data was field checked or converted from address data.

Specific examples on request.

What you describe is one of the problems with coding a large number of addresses. Most of the batch geocoders do not return an accuracy tag with the address. There are exceptions, but suffice it to say they don't. As such you don't know how a batch of 500 addresses resolved. The great majority resolve to the address level, which is to say they are fairly close. Some will resolve to a street, others to a city, some to a zip and others who knows.

Most of the problem is due not to the address, but different street names or even different spellings. As an example, one address I was trying to geocode was on Faithful Ave. according to the website. The correct spelling of the street was Faithfull with 2 L's. Until I corrected the spelling, the best I could get was city resolution, several miles away from the actual. There are times when a street is not in the geocoder's database, then you need 3 or 4 maps with satellite view to track it down.

If you want to take the time to verify a POI, use Extra_POI_Editor and load the file. Double clicking on a POI will bring up an edit window that will show the location from the coordinates in the file. You can then tell the program to recode and it will attempt to resolve to address level. This should correct some of the errors, but unless all the pieces parts of the address are correct, even it can fail. That's why you need to consult the other maps.

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ɐ‾nsǝɹ Just one click away from the end of the Internet

alagave1

alagave1 wrote:

...
COnverting an address to a Lat/Long should not be acceptable. The GPS does this just fine by itself.
...
Am I asking too much?
...

Automated geocoding is more or less how many of the manufacturer supplied POI are created and definitely what occurs when you ask your GPSr to take you to an address. I have personally been taken to an address that was over 10 miles from it's actual location. Certainly not what you would expect from a modern GPS unit.

Many of the POI files found at the POI-Factory were hand coded one by one and are quite accurate. Others may need adjustments to a few or many points in a particular file. Hopefully the author will respond to your requests to make corrections. At a minimum, please try to provide the correct Lon, Lat, Name and Address. I try to verify what I am submitting by plugging the location into Google Earth and using the street level maps whenever possible to verify that I'm looking at the proper entrance to the business or address.

If the author is no longer active, you might ask Miss POI if she will investigate and possibly give you maintainer rights to that file so that you can make the corrections. Remember, we are all volunteers here and try to make this site and its content better all the time.

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"There's no substitute for local knowledge" nüvi 750, nüvi 3597

Quite strong comments

Quite strong comments for someone that has only been here for a week and four days. I would think you could have been a little politer in your comments as it was stated we all are volunteers here and only have some much info to work with. Also it would be nice to send miss poi or the maintainer a side e-mail with the problems identified. In closing it is always good to know when there are problems with a poi made here on he factory. Hope you will enjoy some of the other custom poi's and learn a lot from the kowledge here. smile

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johnm405 660 & MSS&T

mcdonalds

I joined this site because my unit did not have all the Mcdonalds listed, most notably in Iowa. I am so pleased with my McFile. Only 2 errors so far. POIs on the wrong side of the interstate are not errors to me. I can see da Arches.
Edit: I reported them.

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1490LMT 1450LMT 295w