Google maps w/ satellite imagery

[Arnulf Christl]

Camden Daily wrote:
> I'd be very interested in trying to reverse engineer Google's maps as
> well.  The click-and-drag interface is so much nicer than having to
> wait for reloads.

Consider to refrain from expecting "normal" people to act as we "GIS
people" do. We have conducted on and off analysis of user interactions
on heavily frequented map interfaces. Most people never pan a map
anywhere when they are initially navigated to the correct section of the
map they want to see.
So what i think is lot more important ragarding googlemaps is the way
they geocode and reverse geolocate. Imagine Google implementing a
standardized WFS / gazetteer. That would be really great indeed,
interoperable and everything. Google databases already contains loads of
geographically relevant data and information - it has simply not been
tapped yet.

> For all of our applications, losing arbitary zoom levels wouldn't be
> all that bad.  In many ways, it would simplify things, as you'd only
> have to adjust your layers and displays for a preset number of zoom
> levels, without having to worry about how the maps look as they
> approach your various min/maxscales.

That might be true for data that does not change often. It might also be
true for data that you want to see in one coordinate system only. And
for data that you do not want to overlay intersect and visualize with
data from another source. Think interoperable and what googlemaps has
shown us up to now is not worth a penny.

> For turning different map layers on and off, couldn't one just
> generate a different set of tiles for each layer, and create them with
> transparent backgrounds?  I can't see why javascript couldn't overlay
> the different layers of tiles for a final image.  That seems to be how
> Google is drawing their icons over the maps.  Doing it that way would
> also allow for the toggling of layers without the need for a reload.

This is the way most dynamic OWS map clients already do it for quite
some time.

> Of course, the major hassle, as with all javascript applications, is
> supporting the wide variety of browsers out there.  Last I checked
> Google maps only supported IE and Mozilla (not even Opera or Safari),
> though that may have changed by now.

This is a mayor problem and we should not add new problems by sticking
to predefined scales and ignoring the joys of interoperability (as Chris
Holmes pointed out when we were discussing Wikimaps).

Best Arnulf.

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Arnulf B. Christl
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