[Mapserver-users] Basic questions

[Dave McIlhagga]

Hi Mick,

Everything you have identified is certainly achievable and has been done 
in the past with MapServer.  A couple of comments about the approach you 
may want to take:


Mick Ruthven wrote:
> 3. Our application contains a database of locations, each with lat/long
> coordinates. The application determines which if any of those locations are
> "near enough" to the user-entered address. We intend to accomplish this by
> assigning a lat/long tolerance of some fraction of a degree to those
> locations, creating in effect a rectangle for each location, then comparing
> the user's lat/long to the lat/long corners of the rectangle.

A more accurate and simpler approach would be to assign a radius value 
for your points.  MapServer has the capacity to transform a pair of 
lat/lon values into a straight line distance measurement.  So you would 
simply ask if your lat/lon is within x miles of any of your points.


Everything else looks solid - one extra point of interest.  In addition 
to MapServer, you will need some base data for the area that you wish to 
cover.  There are many data providers around -- including free data in 
the US from the Census -- TIGER files which include zip code information 
and street addresses.  There are many commercial enhanced versions of 
TIGER files for sale, clearly you get what you pay for so you'll find 
much greater accuracy with GDT or NavTech datasets.  OTOH, for many 
applications, TIGER data is sufficient.


When taking on mapping work -- be forewarned that there is a lot to 
learn, it's not quite the same as other IT projects.  But everything you 
have indicated can be accomplished with MapServer.

Dave
-- 
Dave McIlhagga
President, DM Solutions Group

http://www.dmsolutions.ca
EMail : mcilhagga at dmsolutions.ca
Phone : 613-565-5056 x15
Fax : 613-565-0925