Re: Forward/backward compatibility

Hi Richard,

On Thu, Nov 13, 2008 at 10:30 PM, Richard Barnes <> wrote:
> There are lots of cases where converting a civic address to a
> lat/long/altitude results in silly results.  I'm sure Martin has better
> examples, but here are a few that come to mind:
> The most obvious one is where the civic address describes a large area, like
> a state or a county.  You can run into this even when the address represents
> a specific unit of land, like a large farm.  Or a large building, like the
> Merchandise Mart or the Pentagon.  (Factoid: The Pentagon takes up 0.004 of
> a degree of latitude.  Merchandise Mart. Both have their own ZIP codes.)

I think your argument can be summarized as follows: some systems only
know the civic address where a set of desktop computers is located.
Given that in a subset of these cases the civic address does not
geocode to a precise (lat, long) pair, then this API should make the
geodetic coordinates optional on the basis that they may not always be

In my opinion, this argument is flawed since the concept of usefulness
should be left entirely to the application that receives the location
data. There are classes of applications that perfectly happy with
city-level accuracy so, to them, the coordinates that result from
geocoding a civic address are perfectly useful.  In case of a building
(where most desktop computers seem to be located), if you were to
geocode such addresses to the center point of that building, then you
would get a (lat, long) pair with an associated accuracy of a few
hundred meters. You mentioned the Pentagon (largest building in the
world): that building has a ground area of ~344 sq meters, so the
accuracy in this case would be roughly 300 - 400 meters. If this is
meaningless / silly, then anything worse than that will also be
meaningless / silly. But GSM Cell-ID providers that are used today on
mobile devices return coordinates with a lot lower accuracy than this,
and practice shows that those fixes are actually useful to many
applications. I therefore don't think your argument is a good enough
reason to make latitude and longitude optional in this API.


Received on Friday, 14 November 2008 13:15:58 UTC