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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
features in the vector layer that I am using are polygons
that represent tracts of land. I presume that because of
the nature of the data that it would be best to retain it as
vector data. I created the vector layer and it is
maintained on our web site. I presume that it would be best
to keep it as vector data. Is that correct?<o:p></o:p></span></p>
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Yes, that is "vector" rather than raster data at its source. The
issue is how best to render it within a web application. I am
assuming that it is authored and stored in a GIS somewhere. The
question is how to get the data from source to web-accessible
location and in format to store it.<br>
<br>
In OL, a vector layer is data that is set directly to js client as
vector and the JS engine renders it. Once the no. of vertices gets
large (>500), then this is slow to transfer and slow to render.<br>
<br>
An OGC web server stand between data sources (eg GIS stores like
shapefile, postGIS, arcSDE, geodatabase) and the web client.<br>
When your OL clients requests data for a BBOX from the server, a WMS
server renders the data on the server and sends this image (png for
preferrence) to OL which locates it on the map. WFS servers by
contrast, send the vector data, by default in GML to the server.
However if you use WMS for display, then you get fast display
rendering (happens on server) even with large data sets while when
you query (eg mouse click, filter query etc) with WFS it only needs
to send a very small amount of data that satisfies the query. You
might want only the attribute data and not the vectices which makes
it even quicker. Things like WMSGeFeaturetInfo can be configured to
return say just the name attribute of the feature under the hovering
cursor. Another mixed-mode method that works well with polygon data
is using UTFGrid in conjunction WMS.<br>
<br>
Your choice depends on host data and preference for server. We use
arcSDE and PostGIS for data with the advantage that there is single
master copy used by both web and GIS (no copying). We use geoserver
as the OGC server. (<a class="moz-txt-link-freetext" href="http://data.gns.cri.nz/pbe">http://data.gns.cri.nz/pbe</a> is the our
application but you need to register to use it -free- because my
masters like to know who is downloading from it).<br>
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