topic Re: Geocoding - issues between coordinate system and layers archieve in Data Management Questions

Geocoding - issues between coordinate system and layers archieve

FlorianKalergi — Fri, 02 Sep 2011 13:31:18 GMT

Good day everyone!

I am using an ESRI Arch Map where I have a number of layers like: roads, cities & villages and counties. Above those, I have another layer where and I brought in it a series of coordinates which can help me to create a map where I can see all my retailers network.

When I chose a retailer location on my map, the coordinates indicate a different position from the real adress of retailers. The difference is between 50-150 meters.
I am triyng to find out what caused this type of errors?!

I must say that all my layers are converted in to Geodatabase Feature Class and Geographic Coordinate System GCS WGS 1984.

Thank you in advance for your time and patience!

Best regards,

Kalergi

Re: Geocoding - issues between coordinate system and layers archieve

JoeBorgione — Sun, 04 Sep 2011 13:03:22 GMT

Good day everyone!

When I chose a retailer location on my map, the coordinates indicate a different position from the real adress of retailers. The difference is between 50-150 meters.
I am triyng to find out what caused this type of errors?!

Thank you in advance for your time and patience!

You mention 'real address'; is this an indication of 'real location'? How did you obtain the coordinates for your retailers? If they were geocoded with an 'address' against a street layer of address ranges, your precision issues should be expected.

Let's say we have a street layer and we match an address 150 Main St against it. The geocoder looks for a street called Main ST and finds a segment that has a range of 100-200 on the even side and 101-199 on the odd side. It's going to figure that address 150 is right in the middle of the block on the even side. The reality might be that the building with 150 painted on the front door is actually at one end of the block.

Accuracy in geocoding is one thing; in my example above, the locator is accurate to the block. If you want precision, that is a X,Y value that better represents the actual location of address 150, you'll need to match against a data source that is better precision built into it (like address points, derived from parcels, gps'd points etc) rather than interpolating against a linear feature.

Hope this helps-

Re: Geocoding - issues between coordinate system and layers archieve

FlorianKalergi — Tue, 06 Sep 2011 07:52:23 GMT

You mention 'real address'; is this an indication of 'real location'? How did you obtain the coordinates for your retailers? If they were geocoded with an 'address' against a street layer of address ranges, your precision issues should be expected.

Let's say we have a street layer and we match an address 150 Main St against it. The geocoder looks for a street called Main ST and finds a segment that has a range of 100-200 on the even side and 101-199 on the odd side. It's going to figure that address 150 is right in the middle of the block on the even side. The reality might be that the building with 150 painted on the front door is actually at one end of the block.

Accuracy in geocoding is one thing; in my example above, the locator is accurate to the block. If you want precision, that is a X,Y value that better represents the actual location of address 150, you'll need to match against a data source that is better precision built into it (like address points, derived from parcels, gps'd points etc) rather than interpolating against a linear feature.

Hope this helps-

Hello Mr. Joe,

You are right. It seem that is an issue regarding the roads layer. I spoke to IT Departament and they told me that problem can be solved by replacing the old layer with an updated one.

I was thinking to do this update by myself, but I guess is not an easy job for an basic user.

Regards,

kalergi