yes I noticed those JSONP requests, and I notice along the payload is the pixel information of width and height for each feature.. that is how they know the borders of each box.<br><br><br><div class="gmail_quote">On Thu, Jul 7, 2011 at 9:36 PM, Phil Scadden <span dir="ltr"><<a href="mailto:p.scadden@gns.cri.nz">p.scadden@gns.cri.nz</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Look more closely at the Net returns. The GET requests to mapslt?layers<br>
are the images, but intertwined with that are per tile (I think) calls<br>
to GET ft?layers which return feature information in JSONP format. You<br>
could do something very similar by making WFS BBOX queries to return<br>
features, but you notice that what is being returned obviously has some<br>
filtering mechanism to limit the no. of features return. (Look at the<br>
returns for whole world versus a zoomed in part). Your hover mechanism<br>
to search points runs out of grunt when over 500 features returned<br>
because they have to be all stored in memory and linearly searched.<br>
<br>
You get some sort of thing with vector file in openlayers (Mapbox does<br>
it with single layer KML files).<br>
<br>
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