Relative Location and Geocoding

Geocoding locations with addresses is rapidly becoming a very reliable way to generate location maps. As we speak there are a wide range of data compiling – from software to actual people – that is improving the primary data correlation between lat/long and addresses as well as advancing into producing reliable results for secondary addresses (like apartment, unit and suite numbers within buildings). As 3d representation advances, so too does the capacity to map interiors, and some places are even providing geolocation of their interior layouts.

Understandably, the closer to an urban core you map, the more accurate your addresses will be. Rural addresses quite often will be placed at the center of the property (when large in size makes finding the access point from the road very difficult), and for properties that are parceled but not developed, there is the issue of address-less locations. Many of these properties have only their relative or surveyed locations as a way to reference that they even exist, without accessing a parcel map of course.

 

Parcel data is another element to the address location game. Many municipalities will charge very large sums of money for their parcel data, and quite often this is because it takes a lot of work to maintain and keep a parcel fabric current. You can’t blame strapped government agencies for wanting to cost recover by selling this data, even if it is counter-intuitive to the core values of the open data movement. Here is the MI 2012 parcel cost survey:

2012 mi parcel

Mapping without Addresses

The concept of relative location is quite simple – where something is i relation to something else of a known location. In this table we find properties with parcel identifiers but no addresses.

land without addreses

 

How do we get directions to look at these properties? One way is to individually contact each rural location’s government office and request a map of the parcel. Once you have the parcel in our GIS you can very easily identify the lat/long, but hunting down all of these parcels individually could take a lot of time and energy – especially if counties require contacting secondary and more local sources within them – all regions manage data in a variety of different ways. Just like the table above shows, a large number of parcels can also be a pricey acquisition.

Eventually all parcels will have addresses logged, but organizing the data takes time and effort that doesn’t

So, in the meantime, there another method that is quick and more cost effective method of finding those elusive properties, simply and easily! All you do is just use the amazing Geocoder designed specifically for finding things based on their relative location.

Thus the diligent and brilliant workers at Tulane University have designed an app that does just that: GEOLocate !!

In natural environments you can specify something like “2 miles up the course of river X from known point Y” or “3 euclidean miles SW of know point X” or in the example above of land without addreses you can use the surveyor produced legal description. Once you find the land boundaries, you can create a lat/long for the point on the property that intersects a bounding road nearest to the position of the centroid.

” Verification and correction of the computer generated geographic coordinates is accomplished using the GEOLocate desktop application. GEOLocate allows users to login to their communities, retrieve and visualize results, make any necessary corrections, provide additional comments, define errors as polygons, and save the results back to the shared dataset. The verified results of Georeferencing can then be downloaded via the portal’s data management interface for re-import to the parent database.”

Margaret Spyker

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