It is a little hard to do, in fact there are several different
'projection systems' in existence. Since the Earth is not flat and
it is not even a perfect sphere, there are many ways to project
latitude and longitude information. You should check a GIS
(Geographical Information Systems) for further info. If the
projection system of each separate source of information is
different from the other, it is hard to make them match perfectly.
Some do plain Mercator, which is latitudes, converted into decimal
numbers, go in the Y axis, longitudes into the X axis. Other
systems preserve the surface area. Satellite pictures have their
own set of problems. The scale of what is in the center of each
picture is different from what is at the edges (lots of trigonometry
involved here) and contiguous pictures don't much unless suitably
distorted.
Now, you are lucky if you are concerned about a small area (a small
city or town) and all your data comes from the same source using the
same projection system. Otherwise, your question is far from
trivial and there are whole PhD thesis written on the subject.
You might try Google maps, they have a programing interface to their
maps, which is for free for non-comercial use but since your e-mail
is of a real estate company, I'm afraid you can't.
See www.qdq.com and try the menu "callejeros fotograficos", it is impresive
Satyam
Yes, Satyan is absolutely correct. The Earth is an Oblate Spheroid
with positive and negative features and taking coordinates from lat
logs is certainly not trivial. There are all sorts of projection
methods to take a three dimensional x-y-z surface and remove the z
portion to project the calculated result onto a flat x-y plane. Even
at a local scale this can be very complicated.
For example, I worked on mapping project re Michigan via a host of
USGS topographic maps and found that many were produced using
different projection methods and some of those projections were 80+
years old and the formulas used had been lost. To do the project
right would have required the resurvey of several entire counties.
However, the detail depends upon the need. For example, if the data
is to be used to find the local shopping mall, that's one thing. But
if it's to determine if your neighbor's fence is on your property,
it's quite another matter.
tedd
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