Here is our new Property layer which includes Parcel outlines (tax lots), Building Footprints, and Addresses which link to PortlandMaps detail screens. This is all coming live from our ESRI ArcSDE server, translation of geometries is performed on the fly using ArcObjects and custom tools.

Use the "Open Placemark" link above, or access it on our website by using the "Property" layer: http://www.portlandmaps.com/google.cfm

The extraction itself is pretty fast, but the KML files end up being in the 100-200k department even with limiting the download area to 1000ft diameter. So we are compressing to KMZ every request which adds about 1 second at the server and client side. Here on our local network we do not do the compression and it is much faster. Still the great thing about GE is you can navigate quickly to the area you are interested in without waiting for things to load first.

Our next goal is to get transparency indexes on our groundoverlays so we don't have the big white box effect. I'm also interested in how good line layers like boundaries and hollow tax lots look when used as groundoverlays with transparent backgrounds. Groundoverlays are much faster for large areas than sending the whole geometries, so we could use them at larger scales and geometries at smaller ones. Though we haven't tried generalizing the geometries dynamically yet (that could be another answer.)

- Phillip Holmstrand & Mike Quetel