Geocoding..........

 
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Bob G. Nuvi 750

It missed me

Of course I have yet to find any map software that get my location correct by address. The main reason is my street counts up by 4's instead of the normal 2's per side In other words I'm 1258 and my neighbor is 1254 instead of 1256. Other than that is does get close you close enough to get what you want. Nice utility.

.

It's so awesome that it's listed in the FAQs. wink

http://www.poi-factory.com/node/821

Geocoding and Reverse Geocoding

Both geocoding and reverse geocoding can be fun to play with. I pulled the coordinates from my county property records and put it in Mapsource and it is dead center of my 5 acre hobby farm. That got me to wondering, do most geocoding and reverse geocoding try to plot location on the midpoint on the street or somewhere else?

Also, just for fun I put my street address in and pulled the coordinates from each and created a waypoint in MapSource for each result. The best results were from Google, iBegin, Terraserver, and USC. Geocoder and Yahoo showed the same results as one another, but seemed to code a different street address than what I had entered. Google and Terraserver may have had an edge over Ibegina and USC, but the differences are probably not significant in this case.

When I used the Determine Street Address from coordinates, Google gives a range of addresses, but both Virtual Earth and iBegin show specific street addresses.

Most were WAY off

Just entered my address and most of the returns were in another subdivision with a similar SOUNDING but different spelling street name. That put the error at over a mile from all but Google and Terraserver which are off by about 100 meters.

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

Cordinates to address - Address to cordinates.any place on a map

a_user wrote:

Just entered my address and most of the returns were in another subdivision with a similar SOUNDING but different spelling street name. That put the error at over a mile from all but Google and Terraserver which are off by about 100 meters.

Thy this web page out. It will allow you to put in an address or point at a location on the google map. It will also allow you to put in an address and show the cordinates.

http://www.itouchmap.com/latlong.html

itouchmap

ampx2 wrote:

Thy this web page out. It will allow you to put in an address or point at a location on the google map. It will also allow you to put in an address and show the cordinates.

http://www.itouchmap.com/latlong.html

itouchmap is one that I use to verify coordinates returned from other geocoders. In fact it's what I used to verify the coordinates from the other sites.

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

Google map coordinates.

You can get coordinates on Google maps without a plugin. Just right click on a location and select "What's here?"

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Alan - Android Auto, DriveLuxe 51LMT-S, DriveLuxe 50LMTHD, Nuvi 3597LMTHD, Oregon 550T, Nuvi 855, Nuvi 755T, Lowrance Endura Sierra, Bosch Nyon

GM is correct

Google Maps not only has it right, but puts the marker centered on my house. All of the others put it kinda correct, but every one of them puts the marker in my street, and some on the side street where I am located (corner lot).

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Nuvi 2595LMT, Nuvi 1490T, Nuvi 260, GPSMAP 195

Geocoding addresses

wknight40 wrote:

Of course I have yet to find any map software that get my location correct by address. The main reason is my street counts up by 4's instead of the normal 2's per side In other words I'm 1258 and my neighbor is 1254 instead of 1256. Other than that is does get close you close enough to get what you want. Nice utility.

My street is in increments of 6, but it was explained to me that's not the reason most address geocoding can be a couple of hundred feet off. I was told that mapping software figures address coordinates using two known coordinates on any given street and figures everything in between mathematically. Where the error comes in, is they base their math on every house being equally spaced on the same sized lot. My house for example is probably 30 feet from the house to the east of me and 60 feet from the house to the west of me. Microsoft S&T also tells me my block goes to 1972 when it actually only goes to 1958.

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Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.

Google Maps

The general indication from the feedback in this chain is that Google Maps is one of the most accurate for geocoding. I will have to try it next time. Thanks for the feedback, all!

Raj

Interesting

I'll have to check this out. I haven't played with the geocoding yet.

seaworthy wrote: Here is an

seaworthy wrote:

Here is an awesome site, I tested it, and it's accurate!

http://stevemorse.org/jcal/latlon.php

Tried the web site listed above tonight. It is apparently blocking request now.

Garmin's E-mail responses

I contacted Garmin via E-mail, about the discrepancy in house numbering.
The attached correspondence may be of interest.
(E-mails have been edited for privacy)

----Original Message-----
From: Not2Bright
Sent: Sunday, November 15, 2009 10:11 PM
To: Cartography Mailbox
Subject: Cartography Error Report

Garmin Product: Nuvi
Cartography Product: MapSource MetroGuide Canada

Cartridge number:

Location of Discrepancy:
Latitude: ***
Longitude: ***
Street Address:
State: Ontario
Nearest City: Ajax
Cross Street: ***
Country: Canada
Zip: ***
Type of Discrepancy:
Missing Feature:
Incorrectly Identified Feature: This part of *** St is incorrectly
numbered. From *** Dr south to *** Ct there are only two (2)
street addresses.
Namely:
18 *** located at Lat/lon***
20 *** located at ***

Other addresses in this stretch are non-existent. The entire block is occupied by these two houses and associated land.
Scale shown on ruler:

-------------------------------------------------------
Source: From: Cartography Mailbox
To: Not2Bright
Sent: Tue, November 17, 2009 6:04:48 PM
Subject: RE: Cartography Error Report

Good evening!

We will check into the address for sure, but let me say the following.
It may be related...may not be...but either way you will run into this
from time to time so it's worth throwing out there anyway.

The addresses are attributed to the lines by full potential postal
ranges (as in 1-99 or 200-299 or in this case even as 1-20 or 21-39).
They are not geocoded by specific dwellings. It is meant to get you
close, but it may not get you right to the exact driveway. There is
averaging in the address attribution because of this...it just is the
way the vendors TYPICALLY gather this data (you'll find it all over the
GPS world).

The longer the "block" of road the more apt you are to see some of this.
Now if you find it locates the address on a totally different block than
it actually is on, that's something else...the road needs some
re-ranging (say the 200 block shows where it is actually the 300 block,
for example). That's a different kettle of fish.

But there is some averaging. As an example, say the address you want is
51 and the potential address range on the road segment is 1-99.. The
software will average that out and put 51 roughly in the middle. That
may not always be reality...51 might even be the first or last house on
the block...but it is put in the middle of the line segment in the map.
As I say, the addressing in the software is meant to get you close...and
hopefully will...but the addresses are not coded to homes
specifically...they are averaged by full potential range along the road
segments.

With what I'm saying above, too, there is a difference between the
actual address range and the potential address range...and the vendors
often geocode the addresses to the roads per the potential range and not
necessarily the actual range and to specific houses and driveways.

On A Avenue, for instance, between 1st and 2nd street the potential
range will be 100-199. There may not that many dwellings in there, but
that is the potential and what is attributed to the line segment.

Best regards,
***
Garmin Cartography Admin
1200 E 151st Street
Olathe, KS 66062
cartography@garmin.com
www.garmin.com
-----------------------------------------------------
From: Not2Bright
Sent: Thursday, November 19, 2009 12:49 AM
To: Cartography Mailbox
Subject: Re: Cartography Error Report

Thank you for your E-mail. It explains why every internet map has the numbering on our street incorrect.

To exacerbate the problem, our street numbering starts at 18, instead of the usual 2.

The postal code for our block is *** (obviously Canadian). There are only 2 addresses in it, ourselves at 18 ***, Ajax and our neighbours at #20.

Once again, thanks for your explanation.

--------------------------------------------------------------------------------

RE: Cartography Error Report
Thu, November 19, 2009 10:46:05 AMFrom: Cartography Mailbox Add to Contacts
To: Not2Bright

I’m glad it helped. I bet at some point these vendors start coding addresses to exact driveways and this averaging ends (it is amazing how much more sophisticated their data has become even over just the last five years), but for the time being, that is how it all generally works with the addressing.

I know it does look weird when you first use one of these things (I live on a road where I see it quite plainly myself…the whole block is 3200-3299, but there are just two houses on the road, and I’m the first—3227. So it puts me about a quarter of the way down the road, but I’m really right on the corner. So I really do know what you are talking about from a personal standpoint, too).

If you have set your HOME waypoint by finding the address before, I’d erase it. Then, when next in your driveway with a good, solid GPS fix set your HOME waypoint by “current location” instead. It’ll make your personal coming and going a bit more precise.

Jumping the gun a bit, but have a good weekend!

Best regards,

***

Garmin Cartography Admin

1200 E 151st Street

Olathe, KS 66062

cartography@garmin.com

www.garmin.com

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nuvi 855. Life is not fair. I don't care who told you it is.

Close

for hand grenades.

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John_nuvi_