[mapserver-users] Dynamic 'OnMouseOver' Info generationvomPostGIS/Postgres

[schroete at iup.physik.uni-bremen.de]

Thanks for the info and links. Just the thing i was thinking of.
Because of the huge amount of (eventually) data points i think i try the
'chatty' version first.
Still tinkering with OpenLayers and changing projection though.

Regards
Heiko


Am 3.4.2009 schrieb "Steve Lime" <Steve.Lime at dnr.state.mn.us>:

>To do this you need some sort of an observer for the map and an image
>map is
>one way to do that. Here's an example:
>
>  http://www.dnr.state.mn.us/ice_out/index.html
>
>In this case the data to be displayed are encoded in the image map
>produced
>by MapServer (I used the template mechanism). So, onMouseOver, a
>function
>is called to display the data object. You could just as easily wrap an
>ajax call
>in that function. You'd need to store a unique ID as part of your image
>map
>sufficient so that you can query postgres. Then the function is called
>you
>pass the ID and then use that to retrieve the additional data.
>
>The image map will work when you have a relatively small number of
>reasonably
>spaced features AND you're interface is not particularly interactive. I
>don't
>think it's possible to combine an image map with your typical pan/zoom
>operation.
>
>Another solution is create a polling capability in your application and
>tie it to
>some sort of an event, such has pausing the mouse for a few seconds. If
>that
>event happens you do a spatial query to see if the user is hovering over
>anything
>and if so you do something. Here's an example site:
>
>  http://www.dnr.state.mn.us/waters/csg/index.html
>
>If you hold your mouse over one of the points on the map you'll get
>details about
>that feature. At each pause a query is done behind the scenes and if
>something
>is found a popup is populated. It's kinda chatty but works. Watch the
>above page
>in FireBug so see the network communication. OpenLayers has a great
>hover control
>to do this sort of thing. You can also use click events, like so:
>
>  http://www.dnr.state.mn.us/waters/csg/index_copy.html
>
>Creating the content to send back will depend on the data. In the above
>cases I use
>MapServer templates to build it. You could use your favorite scripting
>language to do
>so as well.
>
>Hope this helps!
>
>Steve
>
>>>> Heiko Schröter <schroete at iup.physik.uni-bremen.de> 04/02/09 7:44 AM
>>>>
>Hello all,
>
>we are displaying satellite measurement geolocations with Mapserver and
>PostGIS/Postgres underneath.
>
>I would like to add a feature (similar to the MapServer:ImagMap stuff)
>that
>displays some more info about the point on which the mouse is over
>inside the
>map. i.e. geolocation, name of datafile, value or so. These infos can be
>
>sourced from the Postgres db. It is ok to just show these infos on the
>bottom
>window frame (like the MapServer:ImageMap example).
>
>How do i create the html code (javascript or php or whatever needed)
>with the
>dynamic content piped back from the Postgres db ?
>Sorry if this is an obvious question. I did read the ImageMap and
>Template
>stuff, but i cannot get grip to the logic when the data are coming from
>a db.
>
>Any pointer to more info or background knowledge deeply apreciated.
>
>Thanks.
>Heiko
>
>
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