Maureen wrote:
> Ronan Heffernan wrote:
>
>>>
>>>
>>>> Ronan,
>>>> Didn't I see that GRASS can do layers and it can also read SHP files?
>>>> I also believe that it can use the TIGRE data, in which case all of
>>>> the
>>>> street data is in there, you just have to find the street data and
>>>> display it.
>>>>
>>>>
>>>
>>>
>> I have used TIGER (census) data with GRASS, and it can display street
>> maps (for that matter, you are supposed to be able to scan-in raster
>> maps and use a GRASS tool to calibrate them (click on three known
>> points on the map, and tell GRASS their coordinates)). I just wanted
>> to make it clear that GRASS will not tell you the street address, it
>> will only display a graphic of the street map with the desired point
>> plotted (not exactly what a 911 operator wants?)
>
>
> Basically that is what the cell phone companies are telling us. The
> three coordinates would then give a location (within 50 yards) of
> where the caller is. With cell phones, unless they are using a cell
> phone from there home as there main line, you would not get an address
> but a location of where they are in lats and longs, then you could
> plug the lats and longs into a database that would put a spot on the
> map so you know where they are. It's not perfect but right now we
> can't even do that. It's in its infancy here so it would be better
> than what we have which is nothing. Moe
>
OK, I guess it makes sense that street addresses might not be the best
method for locating cell callers in a largely rural county. Since this
is what you want, GRASS will pretty much do this automatically. The
biggest job will be scanning-in and calibrating the map that you want to
use. You won't need a database (not to support GRASS, you might want a
database to keep track of calls?) To plot a point, simply make a text
file like the following (plots three of our SLUG meetings):
-82.51080 27.97409 Tampa
-82.78790 28.00103 Dunedin
-82.32439 27.93889 Brandon
tell GRASS to plot that file. You can zoom/pan using the d.zoom tool
that is built into GRASS. You can also simplify this stuff by writing
BASH scripts that execute inside GRASS. How does this data come-in from
the cell company (FTP, raw TCP/IP, XML, ...)?
Do you already have a linux machine that you can install GRASS? If you
need help (telephone or on-site) let me know, but I am only free
evenings/weekends. In the meantime, I will try to learn how to scan and
calibrate maps.
--ronan
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