[ka-Map-users] Controlling the number of points using addObjectGeo

[Paul Spencer]

Chris,

the number of tiles loaded by ka-Map is limited to the number needed  
to fill the viewport plus a small buffer.  This is typically between  
16 and 36 depending on the size of the viewport (per group).  These  
images are just re-used when the user pans and the image sizes never  
change, even when you zoom so its pretty efficient.  Using  
addObjectGeo creates a new DOM element every time (img, div) and  
positions it over the map images.  This can be very efficient for a  
small number of objects (less than a couple of hundred) but I would  
imagine it would get pretty bad for many images both in loading and  
in the responsiveness of the browser when dragging.

If you really have a lot of data, you might want to consider using  
Lorenzo's stuff or possibly Tim's.  Both are looking at ways of  
incorporating realtime data into a single tiled layer by having the  
layer rendered on the server side, thus avoiding this problem of  
addObjectGeo.

Alternately you could limit the results returned to a set number, or  
only turn on the display of the points when the user zooms to a scale  
that makes it sensible to display them in this way.

Cheers

Paul

On 28-Feb-06, at 4:08 AM, Base Bloc wrote:

> Dear all,
>
>
>
> First off I would like to say that ka-map 0.2 is a fantastic piece  
> of kit and thanks for all the work that people have put in to this.
>
>
>
> I am currently building an application using 0.2 and I am using the  
> addObjectGeo function to add markers along with mouseover events  
> (pop-up windows) to the map. All is working as it should and is  
> looking good. My concern now is the number of markers; the  
> application is covering most of Southeast Asia and the number of  
> markers is going to be high. I am looking to use Ajax to connect to  
> a MySQL database to retrieve the point data relevant to the area of  
> the map being viewed, as if all of the points were to be retrieved  
> in one go it would result in a serious performance hit for the user.
>
>
>
> I’m no ka-map expert, but I was wondering how ka-map does this  
> efficiently with the tiles; as in it gets x number of tiles closest  
> to the area being viewed then moves outwards, is there anyway to  
> use the variable(s) that are being sent to the server to request  
> the tiles to also query the database and return the point data in  
> an equally efficient manor?
>
>
>
> Thanks in advance for your thoughts.
>
>
>
> Chris
>
>
>
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Christopher Brown
>
> Head of Internet Development
>
> Base Bloc Cambodia
>
> #33, 123, Phnom Penh, Cambodia.
>
> P.O. Box 2086
>
> www.basebloc.com
>
> Tel (+885) 12 315 302
>
>
>
> _______________________________________________
> ka-Map-users mailing list
> ka-Map-users at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/ka-map-users

+-----------------------------------------------------------------+
|Paul Spencer                           pspencer at dmsolutions.ca   |
+-----------------------------------------------------------------+
|Applications & Software Development                              |
|DM Solutions Group Inc                 http://www.dmsolutions.ca/|
+-----------------------------------------------------------------+