Question 3 of 15: Address matching

Question 3: Address matching (5 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(a) Address matching (geocoding) is the process of converting a textual postal address — such as "1234 Main Street" — into a map location by matching it against a spatial reference layer whose features carry address information. Most commonly the reference is a street-centreline network in which each segment stores a from–to house-number range and a street name for each side; the geocoder parses and standardizes the input address, finds the matching street segment and side, then interpolates the position along that segment from the house-number range (e.g., number 1234 within the range 1200–1298 is placed about a quarter of the way along). It may alternatively match to a point database of parcels or building points for higher accuracy. The output is a point feature (with a match score) for each address.

(b) Address matching is important because an enormous amount of real-world information is recorded by address, not by coordinates — customer lists, service requests, crime and health records, deliveries, business registries. Geocoding is the bridge that turns such non-spatial tabular data into mapped point features, so that it can be visualized and, crucially, subjected to spatial analysis: density mapping, buffering and proximity, spatial joins to other layers, service-area and routing, and site selection. Without it, the vast majority of administrative data could never enter a GIS as locations.