[ka-Map-users] kaXmlOverlay performance problem

Pg pg.navone at gmail.com
Tue May 30 15:34:16 EDT 2006

What you describe is one of the well known issues of kaXmlOverlay.
An alternative overlay solution, with tiling for big images, has been
provided by Lorenzo Becchi & Andrea Cappugi (kaOverlay.js and related

I will release in a short time a new implementatio of kaXmlOverlay using
vector graphics (<canvas> or VML) to draw lines and polygons.
This isn't the definive solution for your problem, but can help.


2006/5/30, Tamas Szekeres <szekerest at gmail.com>:
> Hi list,
> The current implementation of rendering linestrings and polygons use
> the drawgeom.php (AFAIK).
> The size of the generated overlay image highly depends on the current
> scale of the map. When zooming in the image size may be extremely
> large that increases the download time and the memory usage of the
> browser.
> I think this type of the overlay rendering should be reconsidered so
> as drawgeom should render only a smaller visible segment of the image
> and a new drawing request should be submitted when the user recenters
> the map outside of that image area.
> Any comments would be appreciated.
> Best Regards,
> Tamas Szekeres
> _______________________________________________
> ka-Map-users mailing list
> ka-Map-users at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/ka-map-users
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