>A client wants a database-driven site that records information about real
>estate properties and includes geographic maps of property locations
>(throughout the US). The client has seen a presentation of a
>my preference for PHP/MySQL. I've been Google-searching info on GIS and GPS
>and GMT, but thought it might be worthwhile to ask this discussion list for
>Can anyone direct me to info on PHP presentation of geographic maps -- tied
>to a database with locating coordinates?
You mean something like this (incomplete) project:
The Red "dots" and the long/lat lines are not part of the static image:
They are coming from the database, and being added by GD.
Crude, but effective.
Yeah, if you give every Agent a GPS and record long/lat for each house, you
can plop each of them into any map you have some minimal GPS info for.
Specifically, you'll need to identify two (2) widely-separated landmarks on
each map with known GPS co-ordinates. The Zip Codes are a good starting
point, since the TIGRE data is freely available.
NOTE: End-user GPS units are "off" by like 30 meters (?) on purpose so Joe
Blow can't tell the "enemy" how to find the White House and blow it up.
Sigh. You're never gonna beat that error margin without a *LOT* of repeated
readings over a long period of time and statistical analysis...
For this application, which is pretty much the same as yours only for music
venues, I've found that a mix of GPS and hand-outlined borders of maps is
the best solution.
I'm using the GPS to plop in the "dots", and have the left/right and
horz/vert "scale" of each map in GPS co-ordinates terms.
But, when it comes time to "click" on the USA, that's just a raw set of
points that I outlined using a web-interface, and an image map. I *CAN*
convert any x/y in an image to any long/lat and vice-versa, of course.
But keeping all that junk in the database as 2-D mapping would only be
needed if you're going to be providing driving directions and keeping all
the highways and all that crap that MapQuest keeps (I assume). You almost
for sure don't need all that.
Ya know what? I've pretty much written all the tricky parts of this
You want to just license it or sub-contract me or something? I could save
you a ton of time.
How many properties are we looking at? I've only got 1500 music venues in
The one tricky part is getting public domain maps of the regions you want.
We may need to commission a graphic artist or cartographer to synthesize the
Like Music? http://l-i-e.com/artists.htm
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