[mapguide-users] RE: RE: Google Maps and KML Support

Andy Morsell amorsell at spatialgis.com
Wed Jun 14 12:09:22 EDT 2006

I think that no matter how you obtain your placemarks for Google Maps, the
same client-side performance limitations exist since that is where all of
the parsing of the resultant XML is done.  Yes, performance definitely drags
when a lot of markers are first drawn.  I was initially redrawing the
markers for every view change, but that was slower than it needed to be.  So
now, I cache all markers in a client array, make the call to the MGOS server
to get the next marker set, compare those with the ones in the array and
then only draw the new ones and stuff those into the array.  Performance is
much better now on a session by session basis and the markers are never
cleared off the screen.  Even then, several hundred markers are often drawn
during one event and I haven't seen performance lag too badly.

I've found that doing spatial envelope queries with FDO performance seems
fine but then again, I have not benchmarked that against doing the same in
native Oracle Spatial.  Experience would say that doing it directly in
Oracle Spatial would be a bit faster. 


-----Original Message-----
From: Juan Butler [mailto:jpbutler at pinellascounty.org] 
Sent: Wednesday, June 14, 2006 8:51 AM
To: users at mapguide.osgeo.org
Subject: [mapguide-users] RE: RE: Google Maps and KML Support


I've done the Google Maps thing in the past with Web Services.  It creates
the markers on the fly via the XML that is returned from the Web Service. 
The one, big issue I had was with performance.  It seemed to take a long
time to return the markers to the map.  If I loaded about 100 markers, it
took a very long time.  What do you think about the performance on your
side?    I would probably continue to use the Web Service to return the
marker information for Google Maps.   Do you see any advantages to using the
MGOS resources to query the information.  I was thinking that Oracle Spatial
is much faster than doing some of the complex spatial queries our users ask

I've got the WMS working quite well on my laptop.  Man this is a whole lot
nicer than the Liteview configs I'm use to.   I'm hoping to push some of
these out to our Internet server.

Let me know what you think about the overall performance of displaying the
placemarks on Google Maps.

As for Google Earth, I'm starting to look at what Jason did and getting it
done for .NET.   It seems that Google Earth is a little bit of a memory hog.

I'll let you know if I run into any issues.  

- Juan
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