How to geocode an address to a polygon?

Question

Is there a service that can take an address and return a polygon of the property lines (or the coordinates of the corners of the smallest possible bounding rectangle)?

update: area is Oakland, CA, USA

Answer 1

As @awesomo alluded to, what you really want to query against is a layer containing the parcel boundaries. I don't know that there is an online service that can do batch queries like this for Oakland. Both the city of Oakland and Alameda county have map viewers where you may query individual parcels and return their information.

Here are the respective map viewers:
City of Oakland: Map Viewer
Alameda County: Assessor Parcel Maps

If, on the other hand, your intent is to do more large scale geocoding and further analysis, the situation is a bit more complicated. Ordinarily, I would say to simply download the parcel boundary layer from the appropriate agency, in this case, Alameda County's Geospatial Data Files.

You would then use that layer to set up a geocoding service in your favorite GIS software, and geocode based on addresses.

In this case, you are going to run into a problem of what constitutes data that should be freely accessible to the public, or what is considered value-added, and thus able to be provided at an additional charge. This is a can of worms which I will avoid, but mention later.

Suffice it to say that Alameda County only provides the Parcel boundaries with a few attributes, namely the Parcel Number, and some modified dates for tracking, but no address or other property characteristics. That sort of information is available from the county Assessor's office for an additional fee. Here is their Fee Schedule. You will want to look for the Compact Disc, and either the Entire Assessment Roll (Secured & Unsecured), for $20, or the Entire Property Characteristic File, which is $20,000. Please note the additional zeros for the second option. Hopefully they would include the addresses in the Assessment Roll, but that is by no means guaranteed.

Since this may turn into an expensive option, a second and completely free, though potentially less accurate option would be to instead use the street centerline file as the geocoding basis. This is available from the same download site at Alameda county.
Generally, the geocoders give you the option of including an offset from the line to the proper side based on the address number. Doing this with some adjustment to get the correct distance, should drop the geocoded point inside the parcel boundary, thus letting you do a spatial join between the point and the appropriate parcel boundary. If it doesn't fall inside, you could likely do a query for the nearest point or parcel, depending on which way you go, and get a fairly high percentage match.

To briefly address the discussion of what is happening with GIS data and its place in the public domain, I point you to this article: Does Government GIS Data Belong to the People. This is but a brief discussion, but there is much more information out there, with opinions on both sides of the issue. That discussion, however, is not appropriate for this space.

Answer 2

Google Geocoder with return Bounding Box -

Example: New York http://maps.google.com/maps/api/geocode/json?latlng=40.714245,-74.005838&sensor=false

json response:

"formatted_address": "280 Broadway, New York, NY 10007, USA",
"geometry": {

    "location": {
        "lat": 40.714321,
        "lng": -74.00578999999999
    },
    "location_type": "ROOFTOP",
    "viewport": {
        "northeast": {
            "lat": 40.71566998029149,
            "lng": -74.0044410197085
        },
        "southwest": {
            "lat": 40.7129720197085,
            "lng": -74.0071389802915
        }
    }

},

Answer 3

What you really want is a parcel layer that can be queried. In CA, the counties have this parcel data (of varying degrees of quality), but they don't usually make a public queryable service out of it. They also leave off owner names usually. Unfortunately, I think you will have to purchase a commercial source that compiles the county data. http://www.parcelquest.com/, Core Logic,...

Anyone... feel free to correct me if I'm wrong?