[OpenLayers-Users] WMSGetFeatureInfo + xy mouse coordinates, can this be done?

Tue Mar 1 14:15:46 EST 2011

Thanks again for the help... I think I will try the first point you suggested by using a BBOX strategy. Now I have assigned a min/max scale through my Web Services WFS but this does not seem to come across as the WFS layer shows up immediately after loading the map. Do I have to specify the min/maxextent of the actual WFS layer itself when declaring it?

My whole issue with the WMS layer is.. it works super fast and I can literally turn on/off these 2000+ points in 5 seconds flat.. except when I am doing a WMSGetFeatureInfo the mouse must be situated in the exact center of the point or no feature info is returned.. thus I was trying to use the WFS way and symbol becuase no matter how much the mouse touches the WFS symbol the feautre info was getting returned properly, wish the WMS worked that way :/

________________________________
From: openlayers-users-bounces at lists.osgeo.org [mailto:openlayers-users-bounces at lists.osgeo.org] On Behalf Of Alexandre Dube
Sent: March 01, 2011 12:03 PM
To: openlayers-users at lists.osgeo.org
Subject: Re: [OpenLayers-Users] WMSGetFeatureInfo + xy mouse coordinates, can this be done?

Several thousands is too much indeed.  You could :

  * use the BBOX strategy instead of Fixed to request for features in the current extent only
  * have a WMS layer on zoomed out scales and switch to WFS on zoomed in scales, but you wouldn't be able to interact with your WMS as you do with your vector features...
  * take a look at the GetFeature control and see if that could do the trick (currently not working, but look at the code to get the idea) :
     http://dev.openlayers.org/releases/OpenLayers-2.10/examples/getfeature-wfs.html
  * setup an OGC filter to your vector layer to get only specific features (if your data have some kind of attribute you could filter on), and make only specific features display on specific zoom levels.  I already did something like that, see an example here : http://bs-dev2.mapgears.com/webmap/

Best regards,

Alexandre

On 11-03-01 01:35 PM, Andrew Stewart wrote:
Actually I modified the strategies to be -

strategies: [

new OpenLayers.Strategy.Fixed(),

new OpenLayers.Strategy.Cluster()

],

Now I am getting the points showing up but there is still quite a delay in loading / zooming etc. Is there anyway I can optimize this further by limiting features etc?

________________________________
From: openlayers-users-bounces at lists.osgeo.org<mailto:openlayers-users-bounces at lists.osgeo.org> [mailto:openlayers-users-bounces at lists.osgeo.org] On Behalf Of Andrew Stewart
Sent: March 01, 2011 11:31 AM
To: openlayers-users at lists.osgeo.org<mailto:openlayers-users at lists.osgeo.org>
Subject: RE: [OpenLayers-Users] WMSGetFeatureInfo + xy mouse coordinates, can this be done?

So I am having success with point features below 100.. but is it also possible to use this with many point features (several thousand?)

My code below is trying to use the cluster strategy.. previously it was Fixed but that causes my map to freeze when loading the several thousand points. But when I switch to cluster nothing happens and no points appear, any advice on what I'm doing wrong?

 //Hydrant
   var test_hydrants = new OpenLayers.Layer.Vector("Hydrant", {

        strategies: [new OpenLayers.Strategy.Cluster()],

        protocol: new OpenLayers.Protocol.WFS({
            url: wfs,
            featureType: "Hydrants",
            featureNS: "http://www.intergraph.com/geomedia/gml",
            featurePrefix: "gmgml",
            srsName: "EPSG:3776",
            //filter: filter,
            geometryName: "Geometry",
            version: "1.1.0"
        })
    });

           //Add Vector Layers to Map
       map.addLayer(test_hydrants);

________________________________
From: openlayers-users-bounces at lists.osgeo.org<mailto:openlayers-users-bounces at lists.osgeo.org> [mailto:openlayers-users-bounces at lists.osgeo.org] On Behalf Of Alexandre Dube
Sent: March 01, 2011 7:52 AM
To: openlayers-users at lists.osgeo.org<mailto:openlayers-users at lists.osgeo.org>
Subject: Re: [OpenLayers-Users] WMSGetFeatureInfo + xy mouse coordinates, can this be done?

50~ shouldn't be a problem.  IMHO, it would be a good idea to make the switch to WFS.

Cheers,

Alexandre

On 11-03-01 09:39 AM, Andrew Stewart wrote:

Ok thanks.. So basically if my web service does not support tolerance (which I'm pretty sure is the case) then there is not much I can do with openlayers to fix this problem.. Besides possibly changing my features into markers from my WFS and giving those markers tooltips/hotspots but not sure what the performance would be on that since I need sometimes 50+ markers.

-----Original Message-----
From: openlayers-users-bounces at lists.osgeo.org<mailto:openlayers-users-bounces at lists.osgeo.org> [mailto:openlayers-users-bounces at lists.osgeo.org] On Behalf Of Alexandre Dube
Sent: March 01, 2011 6:49 AM
To: openlayers-users at lists.osgeo.org<mailto:openlayers-users at lists.osgeo.org>
Subject: Re: [OpenLayers-Users] WMSGetFeatureInfo + xy mouse coordinates, can this be done?

Hi,

That could be setup in your web mapping service. If you use MapServer,
you could set the Layer object definition "TOLERANCE" parameter for that.

Regards,

Alexandre

[1] http://mapserver.org/mapfile/layer.html (search for "TOLERANCE")

On 11-02-28 10:02 PM, Planet)x wrote:

I have a slight problem which has to do with my WMS mainly but wondering if
there is a way to program around it. Well problem is I can increase the
symbol size for points on my Web service but the geometry of the point
(centroid) remains the same. Therefore when using a
OpenLayers.Control.WMSGetFeatureInfo the feature info is never returned
until I move the mouse directly in the middle of the point feature (and also
lines unfortunately). Question is can I somehow force the mouse to be moved
to the center of the point when it nears a symbol.. and is there anyway to
actually get the entire coordinates for the symbol so I can use them to do
the featureinfo somehow? Not sure if this makes sense or if there is another
approach I can utilize to do this.. appreciate any advice!

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--
Alexandre Dubé
Mapgears
www.mapgears.com<http://www.mapgears.com>

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--
Alexandre Dubé
Mapgears
www.mapgears.com<http://www.mapgears.com>

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