[Developers] mapping Zip codes to other location info?

[Karell Ste-Marie]

Well, that depends on what we are trying to accomplish here. If we want we
can put a structure that will allow every house to have it's own geolocation
- fine. But what do we use? The front door? The center of the house? The
center of the property? What if the property is not a square or rectangle?
This opens up a huge can of worms.

While I understand that you are not suggesting that we implement geolocation
for every rock on the planet I question the need to have such granular data.
What you are suggesting is that every house (or property) should have it's
own long/lat and I personally think that this is overkill. While I can
understand the argument of the required precision of having a proper
long/lat for an airport again I must ask: the geolocation of what? The
communication tower? The parking lot? The landing runway? Which one? An
airport is a pretty bit place and if you compare it to a zip code I think
it's safe to assume (at least in Canada where the zip codes are usually
quite precise) that an airport can span multiple zip codes in the sense of
square feet. So if that is the case, then the zip code is actually more
precise for this exercise than the airport's geolocation itself.

http://srmwww.gov.bc.ca/gis/storageprecision.html
On a 9 significant-digit geolocation long/lat you have meter (4 four feet)
precision, using 11 significant-digit precision you will have centimeter
precision (1/3 inch). Then with single-precision you will have 100-meter
precision (most GPSes), with double precision you will have 1.9cm precision.
So taking this into account, you would have to include an array or a
3-dimension address (or a from/to/elevation to create a rectangle).

Personally, I still think that dead-center is the best thing to do and if
you need more precision then you can put it in on a per-case basis. But
expecting someone to figure out their long/lat for their own home will lead
to many mistakes. The UPS man may think that it's 50 miles away to send a
package to my next-door neighbor.

Can we meet in the middle and say that you can have geolocation for a zip
code and for an address but that the address may default to using the zip
code's?

-----------------------------------------------
Karell Ste-Marie
MCP, MCP+SB, MCP+I, MCAD, MCSE
http://karell.blogspot.com/
http://bodyspace.bodybuilding.com/n5d/
http://blog.bodybuilding.com/n5d

-----Original Message-----
From: Paul Tomblin [mailto:ptomblin at xcski.com] 
Sent: Monday, September 10, 2007 2:26 PM
To: Karell Ste-Marie
Cc: developers at freebase.com
Subject: Re: [Developers] mapping Zip codes to other location info?

"Most" applications.  An airport has a Location, but it also has an
address.  That address has a Zip Code.  If you include the type "Zip Code"
and the type "Location", which lat/long are you going to get, the one for
the airport, or the one for the zip code centroid?  That might not make
any difference for calculating UPS shipping rates, but it sure as hell
makes a difference if you're flying there.