Client-side vector-based internet-browser-embedded map viewer

[Woody Wallace]

Check out the Lava/Magma setup at:

http://www.pgs.nl

Although their demos are of smaller areas, my prior work at the USGS
involved integrating that system with with some very detailed databases.
Our client ended up being relatively thick, but usable on a wide variety of
platforms assuming they had enough memory (~128 Mb of ram) to render large
vector datasets.  We attempted to implement a variety of methods for
optimizing data transfer:  Server-side attributes, scale dependent layers,
on-the-fly clipping and generalization.  You can look at that example at:

http://geode.usgs.gov

There are some real advantages to sending the vector data to the client.
However, the utlimate question remains.... How thick do you want to your
clients to be?  The computer industry has sea-sawed on this issue for
years.  Big mainframes--dumb terminals  to the personal computer revolution
and now the trend is back to thinner clients on portable systems.  It is all
a processing/memory game.  If your clients have lots of processing power,
its more efficient to take advantage of it.  If not, your stuck processing
everything on the server and sending back a static picture (something
mapserver seems to be very good at).

There have been standards for transfering data between remote databases long
before OpenGIS came along. One is called ODBC.  All you need is a Java
client and a JDBC-ODBC bridge and you have connectivity to a wide variety of
mainstream databases which is where GIS data is being stuffed these days
anyway.  No waiting of GML or other industry specific standards that are
probably less efficient anyway.  The real issue that the OGC will sort out
is data discovery not transfering the data itself.

Bottom line... Vector based webmapping already exists.  It provides some
neat functionality for high end clients.  If you want to reach a broader
audience, image producing servers such as mapserver are probably the way to
go.

Adeus,

Woody Wallace
Wisconsin State Carographer's Office


Nicolau Werneck wrote:

>    Hello.
>
>    Kind of off-topic, sorry, but have anybody here
> ever worked with any of those map browsers in the
> topic? I have seen some flash map viewers, with
> scalabel graphics, layer control and feature search,
> but I've only seen applications for small areas... Is
> it reasonably fast for more detailed areas, say, the
> size of Portugal, with some 800 rivers, roads and etc?
>    I know there are other solutions for this kind of
> application... This flash one can't handle labels and
> symbols :Q
>
>    Well, bye! :)
>
> --Nicolau
>
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