Well, it's up to you how to model the objects (that's the great
thing about relational databases). Typically, I've added a table of
"Historical Positions" with basically the same structure as the
"vehicle" table (but in that case the unique key is not the vehicle ID,
but instead just a system assigned key like OID). As for the points
passed by, I would not save that information in a table, instead
consider it the result of a spatial query (say in a PostGIS view) at
display time.
A system like this usually takes a large of amount of time for
requirements, investigation, design, and prototyping. And of course,
construction, testing, documentation, and training. If you want
something more packaged you can just download and install, you may want
to do some searching on the web.
Best Regards,
Brent Fraser
On 6/17/2011 10:56 AM, Saka Royban wrote:
Thanks for ur answer and also Josh's answer.
In fact, i should be able to display path of vehicles (usually more
than 1 vehicle in display area) and also be able to save points passed
by vehicles and time of passing (for some queries). Cause of that, i
thought maybe i need one table per vehicle.
Do u think any more idea?
Best Regards
------------------------------------------------------------------------
*From:* Brent Fraser <bfra...@geoanalytic.com>
*To:* Saka Royban <sakaroy...@yahoo.com>
*Cc:* MapServer <mapserver-users@lists.osgeo.org>
*Sent:* Fri, June 17, 2011 7:49:20 PM
*Subject:* Re: [mapserver-users] Asking for guidelines about a project
The database schema depends on what you want to do with the data
(display current position? A track of historical positions?), and how
much data you expect (how may objects will be tracked? how often will
they report?).
A simple schema would have one table (e.g. "vehicles"), with one row
per tracked object
Table: Vehicles
ID: Name: Position: Status: UpdateTime:
1 My Car point(51,-115) active 2011-06-16 10:23:54+02
2 Another Car point(52,-116) inactive 2010-05-15 11:13:12+02
With this schema, when a new position arrives for "My Car", an update
statement is issued to change the row's Position and UpdateTime (and
possibly Status).
The table is treated as a PostGIS point layer by mapserver.
In my implementations, the position data was updated every 30 to 60
minutes (they were ships and construction vehicles), so there was no
need to ask mapserver to regenerate a graphic every second; an updated
map was shown whenever a user did a pan or zoom. You may be able to
configure OpenLayers to do a CGI request to mapserver every few
seconds, but I've never done that.
Best Regards,
Brent Fraser
On 6/16/2011 11:52 PM, Saka Royban wrote:
Thanks a lot brent
I checked provided link and i;m gonna give it a try.
About ur helpful advices, i'm confused about how to save data in
PostGIS? with what schema?
I mean i have to keep track of each paced point by moving objects.
Should i record each point as a record, so it means one table per
moving object ?
Also for displaying these varaiant data, there should some sort of
plan. I don't think i'm able to say to MapServer CGI at each second
connect to PostGIS and read the new data, then i have to use
MapScript. Am i right? (Can this process be done via OpenLayers?)
Best Regards
------------------------------------------------------------------------
*From:* Brent Fraser <bfra...@geoanalytic.com>
*To:* Saka Royban <sakaroy...@yahoo.com>
*Cc:* MapServer <mapserver-users@lists.osgeo.org>
*Sent:* Tue, June 14, 2011 7:14:08 PM
*Subject:* Re: [mapserver-users] Asking for guidelines about a project
Saka,
I've had good success using PostGIS for data storage in
implementing tracking systems. While you'll need to create your own
code for updating the positions in the database, mapserver can read
points from PostGIS and can render the points into a map image for
use with the OpenLayers client.
There are other solutions too, like OpenGTS
(http://opengts.sourceforge.net/index.html)
Best Regards,
Brent Fraser
On 6/14/2011 12:08 AM, Saka Royban wrote:
Hi all.
Strictly Speaking, i have a project that i should display some
moving objects on a map via browser.
Generally, i don't know how to start? i mean how should i save these
time-based objects in DB and how to retrieve and display them via
Mapserver? where should i use client side scripting like OpneLayers?
Any help woudbe greatly appreciated.
Thanks in advance
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