[webmap-discuss] OGC and google style tiling

Bart van den Eijnden bartvde at xs4all.nl
Wed Apr 12 04:18:36 EDT 2006

Hi Steven,

there is an OGC list to discuss tiling:


check the archives there.

What you could also do, since I assume your data is pretty much static, is
use UMN Mapserver to rasterize all your vector data (create Geotiffs e.g.)
and serve out the rasters instead. I guess the classifications used are
heavy on CPU usage, and pre-classified rasters would solve that part at

Best regards,

> Hi all,
> For those who don't know: I'm one of the lead developers on the EduGIS
> project, a site which aims to introduce highschool students to GIS. The
> site contains a webmapping part, which combined with so called
> 'lesson-modules' can be used inside the classroom.
> We aim to be able to have at least 200 students access the site at one
> time. Since it's being used inside the classroom it means that a lot of
> students will do more or less the same thing at the same time (following
> the tasks in the lesson-modules). This causes quite some stress on the
> server. Since it's a free site we have limited budget and cannot put a
> google-style server park behind it ;(
> Right now we've got apache to serverside cache the umn mapserver output.
> This obviously works only for those images that are requested twice
> (like the first mapimage). Right now about 30 students can work at the
> same time without it becoming unworkable slow. Since serverside caching
> works, the next logical step to boost performance would be using tiles
> like google.
> But..
> From what I know, tiling breaks OGC compatibility, right?
> We're using Mapbuilder as client and we prefer to keep using it, since
> it's turning into a rather featureful client on the EduGIS site. But the
> question arises how to implement tiling inside WMC/OWS-context without
> breaking OGC too much.
> Also I'm interested in the used algorithms to get tiling working.
> Cheers,
> Steven
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