POI accuracy

 

I recently found this site. It really nice that people would take the time to do all this.

Sadly, the POI files are so badly riddled with errors it makes them unusable.

For example I downloaded the file for Love's truck stops. I have one in my area. The POI file shows two . It Puts one where one does not exist and puts the second on a wrong road 6 miles away.

Could it be me? Or is it the Garmin 360? Or is just bad data input?

So, I tried a second file. Travel America truck stop. Again , there is one in my area. The POI file put the truck stop smack dab in the middle of a residential area and miles from the actual location.

Where does the problem lie?

If you find errors in the

If you find errors in the file you can contact the original author and let them know about it so it can be fixed.

We are a community based site that works mainly on the honor system. There really is no way to guarantee that the info is accurate, we just do our best with the information we get and hope that users like yourself will help us make the needed corrections.

Miss Poi

Were just humans so there

Were just humans so there are plenty of mistakes. There is a tool "POI Verifier" that checks various syntax of the files and the POIs have been greatly improved recently.

As far as your specific question.. bad data in is bad data out. You'll just need to post your recommended changes and the author should fix them OR be proactive and post the updates to the site.

--
eTrex Touch 35, Nuvi 1350LMT, Nuvi 350, Nuvi 260, Garmin GPS III, Basecamp

Good Question

I, who have not used a POI to date, have pondered the same question before actively seeking to install them. The first question, regarding accuracy, is subject to the source of information I would guess. In other words, did someone use the Internet to gather the information or did the person actively seek the sites in person. Another source could be other third hand information such as word of mouth. As one who dealt with a massive change of information daily in my former career, I know the changes are ongoing and constant. Another possibility could be with transposing of coordinate data or other data entry errors.

The second question I would have is how often the data files are updated. This becomes the real touchstone of problem solving. A number of businesses may sit in one spot for decades while others move frequently in order to expand or garner more business. With POI files, considering that people like you and I are the ones creating them, I would conclude that updates are not all that frequent.

What would be nice, I suppose, is some sort of national database of businesses, sites, et cetera but to be realistic such a database would be unbelievably large and subject to any number of errors.

Thus, I would think that the POI files could at most be a guide and not something you would absolutely rely upon for information.

--
Garmin DriveSmart™ 65 & Traffic in Bakersfield, CA

I have found that for the

I have found that for the most part the file that I have downloaded have been fairly accurate. Only a handful of errors amongst tens of thousand of locations in the ones I've downloaded.

As others have mentioned, small errors can happen due to a variety of issues. No biggie. As a community, we help out by reporting (and possibly fixing when possible) these errors.

I've Made several POI files

Three, to be exact. One file are locations where I have personally been with a GPS and marked the position. So the Airport National Car Rental site file contains locations that I have verified. But it does not contain all National Car Rental sites, just the ones I have been to.

The other two ExxonMobil gas station files were derived from that company's location information from their website. Those addresses were then converted by batchgeocode - so there could be inaccuracuries introduced by the conversion. Also, as the file ages, some stores will go away and others added that are not in the file.

--
___________________ Garmin 2455, 855, Oregon 550t

Since , I don't know how a

Since , I don't know how a File is made maybe you can set me straight before contacting an author. A file is made with coordinates? Or is it made for the GPS to read the input address?

IF you go to the below link you will see the entry with the correct address.

http://creeperscobra.com/drop/gps/263.bmp

Second link shows the poi place by the file and my pointer of where it actually is. Approx. 6 miles away.

http://creeperscobra.com/drop/gps/249.bmp

Another error I found was that it put the fuel station about 5 miles out in the middle of the wooded marshes.

Do I need the coordinates for correction as both errors had the correct addresses.

That's three file downloads and all the entries I checked where miles off and some did not exist.

Errors

I have created some, helped add to, such as the one I'm working on now for Hilton hotels, and have uploaded someone elses and have had no callbacks or errors on the ones I used from others. So far the only mistake I have found is the dead end street Garmin itself keeps sending me to when I go to my sons new house in New Jersey. Nothing is perfect. Instead of being so critical, perhaps you'll learn how to do this and make your own POIs for yourself. I think you should follow what everyone before me has told you. Email said mistakes to the author and ask him to correct , if necessary.

None of want to make errors, but if shown, I would be glad to research and correct my own errors, as I would believe everyone else on this site would.

Stop criticizing, learn and help out.

Alan

--
Alan-Garmin c340

.

creeper wrote:

Since , I don't know how a File is made maybe you can set me straight before contacting an author. A file is made with coordinates? Or is it made for the GPS to read the input address?

IF you go to the below link you will see the entry with the correct address.

http://creeperscobra.com/drop/gps/263.bmp

Second link shows the poi place by the file and my pointer of where it actually is. Approx. 6 miles away.

http://creeperscobra.com/drop/gps/249.bmp

Another error I found was that it put the fuel station about 5 miles out in the middle of the wooded marshes.

Do I need the coordinates for correction as both errors had the correct addresses.

When you open the POI file on your PC, is the address listed for the locations that are wrong?

If so, you can check that against the actual address? That might be where the error was introduced.

Most of the files are constructed by geocoding the addresses. If the address is incorrect for whatever reason, then the lat and long will be off.

Once the correct address is known, then it can be geocoded and the file updated.

Here's what the lat and long should be for the location you posted in the pictures you linked.

Address 8436 FORD AVE
City RICHMOND HILL
State/Region GA
ZIP/Postcode 31324-6410
Country US [United States]
Latitude 31.961647
Longitude -81.332111
Coordinates N31°57.69882, W081°19.92666

Lighten up Alan. If you read

Lighten up Alan. If you read what I said I'm trying to determine WHERE the error is , before proceeding.

IF the product is showing large amount of errors (11 I found in one file), it could be the GPS or the coding. That's why I ASKED. I would determine where the error was BEFORE contacting the owner if his file is not at fault.

I thought it might be the GPS as one of the points was miles out in wooded marsh land.

But , thanks for criticizing me. I was asking for assistance in finding the error to proceed to correct the problem, which your post was no help at all.

Thanks Mamma,I opened the

Thanks Mamma,

I opened the file and the address wasn't off. So, I'm assuming the read from the GPS is the Coordinates and not the address that is typed.

Your Coordinates are nearly spot on what I got. They are off from what is in the file.

Thanks for you help. I'll send the corrections off to the author now that I sure where the error lies.

POI's

Wow, Creeper, I am relatively new to this site as well. I happenchanced also and am quite pleased with the information I have found and been given here. No one is forcing you to load the POIs. And if an error is made, hey, it may or not be corrected. I was looking for gas/petrol (glad I clarified that) on the way home from Philly, and there was no station where it told me there was to be one. I just shrugged it off. Life is too short. The folks on this site are awesome. Ce la vie!!!

Hi Bobby, That's why I

Hi Bobby,

That's why I asked if it was the file , the gps or me.

Kinda hard to shrug off a non-existent when your in a 38 foot RV towing a car and it leads you down to a marsh front. At 60 feet long you have to be careful which roads you travel.

I agree the folks are awesome.
But, If you can't ask questions without some people jumping down your throat then it won't stay that way.

The only bad question is one not asked.

Several Possibilities

creeper wrote:

Thanks Mamma,

I opened the file and the address wasn't off. So, I'm assuming the read from the GPS is the Coordinates and not the address that is typed.

Your Coordinates are nearly spot on what I got. They are off from what is in the file.
Thanks for you help. I'll send the corrections off to the author now that I sure where the error lies.

First, the GPSr reads the longitude and the latitude. There are several possibilities for errors in files:
1. If they are all off, the author might have used the wrong coordinate system, i.e. should be using decimal, not degree, for example.
2. Sometimes two geocoding systems produce different results for the same address. Usually these are not great differences, but they can result in misplacement.
3. When geocoding large numbers of addresses, sometimes the system, for example batch geocode, does not find the street but then outputs the closest information, ie. the center of the zipcode or the center of a city, for example. You need to be very dilligent, and it is easy for these types of errors to creep in, as it is not always evident. This is one of those cases that other users responding to errors is very helpful.

--
Garmin StreetPilot c530, Mapsource

FYI>>>

llabmik wrote:

I, who have not used a POI to date, have pondered the same question before actively seeking to install them. The first question, regarding accuracy, is subject to the source of information I would guess. In other words, did someone use the Internet to gather the information or did the person actively seek the sites in person. Another source could be other third hand information such as word of mouth. As one who dealt with a massive change of information daily in my former career, I know the changes are ongoing and constant. Another possibility could be with transposing of coordinate data or other data entry errors.

The second question I would have is how often the data files are updated. This becomes the real touchstone of problem solving. A number of businesses may sit in one spot for decades while others move frequently in order to expand or garner more business. With POI files, considering that people like you and I are the ones creating them, I would conclude that updates are not all that frequent.

What would be nice, I suppose, is some sort of national database of businesses, sites, et cetera but to be realistic such a database would be unbelievably large and subject to any number of errors.

Thus, I would think that the POI files could at most be a guide and not something you would absolutely rely upon for information.

The POI files I created (New Hope PA and LL Bean stores)were done by taking the location address, typing it into Mapsource and marking the waypoint. I have tested the Flemington NJ and Freeport ME LL Bean POIs and a couple of the New Hope restaurants...all were accurate. The only problem I found with the New Hope file was that some of the establishments are close together and that could be a bit confusing...

I asked the owners to close and move further apart, in the name of good GPSing, they were not anxious to comply smile :)

Regards, Ted

--
"You can't get there from here"

Thanks Mkahn, Great

Thanks Mkahn,

Great explanation.

POIs

I have been creating some of the POI here and it is hard.. I do use differnt tools to get the proper information. I have also found that sometimes these tools are off even if you put in a propler address. I do count on the users to give me input back so that I can correct them. And yea, There has been some address errors but as it is reported to me, I will correct it. Most of the areas that is in my POI files, I have not been able to go to. I hope this helps in understanding..

BTW I know you were just wondering if the files were off due to you GPS or just off in general.

--
Bobkz - Garmin Nuvi 3597LMTHD/2455LMT/C530/C580- "Pain Is Fear Leaving The Body - Semper Fidelis"

With the help here I was

With the help here I was able to rule out the GPS. Which I thought it might be. It's a brand new Nuvi 360. My other Garmins don't except POI.

Looking at the coordinates and checking the actual coordinate it was the coordinates that were way off.

I think as Mkahn said the tools used just point the point in the middle of somewhere when the address could not be found.

'Result Precision' Indication

I've notice that when entering a single address in gpsvisualizer.com it displays the precision of the resulted coordinates, i.e. address, street, city, and state .... depending on what input it recognizes. I would assume the 'Batch Geocoder' of gpsvisualizer.com works the same way.

RT

--
"Internet: As Yogi Berra would say, "Don't believe 90% of what you read, and verify the other half."

There is a way to check this also...

miss poi wrote:

If you find errors in the file you can contact the original author and let them know about it so it can be fixed.

We are a community based site that works mainly on the honor system. There really is no way to guarantee that the info is accurate, we just do our best with the information we get and hope that users like yourself will help us make the needed corrections.

Miss Poi

I would like to add to Ms POI's comment...

You can double check the location with Google Earth (just download and install -- it is free). I did that and now I uploaded the red light camera file and it works great. It is giving me warning for the cameras I reported when I get in close proximity of them (say 1000 feet or less). Which makes me believe that Google Earth is giving me the right coordinates (or at least very close -- with few feet error margin).

You can test it yourself by entering the coordinates of the truck stop you suspect has wrong ones and then (that would be even contributing to this site) post the corrections here and the authors will gladly take care of this. Or better... use your Garmin 360 to save the truck stop and then compare with the google earth coordinates, then post here.

Happy navigating!

--
The only things you regret in life are the chances you never take.

Second Thoughts

The only bad question is one not asked.

I must have said that a million times during my past profession. I really didn't think I was coming off that strong. What I was trying to say in my New York fashion(in answer to you saying we made lots of errors), stop complaining, roll up your sleeves and learn and then jump in and help. This is not just a great website, it's a great bunch of people.I have learned alot in a short time thanks to everyone who responds to my questions.

So I apologise and say welcome.

Alan

--
Alan-Garmin c340

Second Thoughts

AMEN!!!!!!!!!!!!!!!

Brand new...

creeper wrote:

With the help here I was able to rule out the GPS. Which I thought it might be. It's a brand new Nuvi 360. My other Garmins don't except POI.

Looking at the coordinates and checking the actual coordinate it was the coordinates that were way off.

I think as Mkahn said the tools used just point the point in the middle of somewhere when the address could not be found.

Even if it a brand new 360, I'd recommend visiting Garmin's web site and checking if there is an update of the device software. It is a good idea to keep up to date your device.

Welcome to the group again and you all guys... take it easy. We're just helping each other and it is human to err.

--
The only things you regret in life are the chances you never take.

Covered Bridge Story

I've installed several POIs from this site and they've all been pretty accurate. However, I recently found a site that could use an explanation in a POI for covered bridges in Maryland.

I've been driving near this covered bridge site for years and never knew there was a bridge nearby until until I installed this POI. The next time I drove that route I followed the directions to the bridge but there was no bridge when I got there. When I got home I googled covered bridges in Maryland and found a description and picture of the bridge. The funny thing was that it was located about a 1/4 mile out in the middle of cow pasture with no road to it. The online picture even showed the bridge with cows standing in and around it. The POI location had shown the nearest road location but there was no explanation about where the bridge actually was. I do plan to send a note to the author about this.

Google or Yahoo

I have made a grand total of three POI's so far, so clearly I am not an expert. Still, I have found that there is a big difference in batch processing the information using Yahoo vs Google (which is typically more accurate). There are many variables with how you enter the data and generally, the most accurate is to look up each one independently on Streets and Trips or MapSource. Even then, it is not always the best, but usually it will get you very close. Many of the POI's also include the phone number so you can call if required and in all cases, anyone who submits would gladly update the file with any corrections you can offer...

Google or Yahoo (or MS Live)

fjr15288 wrote:

...Still, I have found that there is a big difference in batch processing the information using Yahoo vs Google (which is typically more accurate)...

This is due to Google's more recently updated source. The sources Yahoo uses are older. I noticed that by trying to find a location of a store in a mall. In Google it was giving me the right address though some parts of the mall were still in construction, however Yahoo maps had no mall at all at this place and could give me only approximate locatoin. This road did not even exist on the Yahoo map.

MS source is also older than Google's, because local.live.com was showing similar picture to that of Yahoo.

--
The only things you regret in life are the chances you never take.

Was going to send a message

Was going to send a message to the author, but no contact page.

Then just send a note to

Then just send a note to miss poi.

Was going to send a message

creeper wrote:

Was going to send a message to the author, but no contact page.

Just click name and you can email most people.

Alan

--
Alan-Garmin c340

But some people don't have

But some people don't have the contact tab enabled in their profile.

Contact

That's why I said most.

Alan

--
Alan-Garmin c340