[OpenLayers-Users] Hard to click on points for GetFeatureInfo

[Mike Carsella]

All,

I have the same problem with getfeatureinfo on line data using MapGuide Open Source WMS and OpenLayers.   I think it's a bug in MapGuide.  Polygon queries work OK.

  ----- Original Message ----- 
  From: Marc Desharnais 
  To: users at openlayers.org 
  Sent: Friday, July 20, 2007 9:21 AM
  Subject: Re: [OpenLayers-Users] Hard to click on points for GetFeatureInfo


  Hi all,

  For the record, I asked the geoserver team and it seems that no such options exists for now. The problem is that for now they do a getinfo on the coordonates of the geometry (a point in my case) instead of the representation (likely a circle for me). The representation is larger than the geometry so you get the feeling you can click anywhere in the cercle to get info. 

  By reality is really different ;)

  This issue is opened in their bug base so I guess it will be fixed in the next versions.


  Regards,


  Marc





  Dmitri Mizerkin wrote: 
    Mi Marc,

    so you have to request feature from the server, not feature info.

    A click event on a map returns the values for x and y in the view port. You should make a box of those adding and substracting a custom tolerance value. After you've done so you got 4 values: minx = x - tolerance, miny = y - tolerance, maxx = x + tolerance, maxy = y + tolerance. These can be converted to latitude-longitude values using OpenLayers ( map.getLonLatFromViewPortPx function). After all of these actions you get your BBOX so you can send a request to the geoserver like this: http://your_host/geoserver/wfs?REQUEST=GetFeature&SERVICE=WFS&VERSION=1.0.0&TYPENAME=your_layer_names&BBOX=your_bbox&MAXFEATURES=10

    That's the only workaround I know.

    Cheers,
    Dmitri 


    2007/7/20, Marc Desharnais <marc.desharnais at ec.gc.ca>: 
      Hi all,

      I'm using geoserver so I guess your solution won't work. Anyone has an
      idea about setting a tolerance level in geoserver?
      Or anything that would make it easier to click on a point of a map with 
      geoserver.


      Thanks,

      Marc


      Dmitri Mizerkin wrote:
      > Hi Bill,
      >
      > that's the right way to do it. What I meant is setting the tolerance
      > via URL, in your case it would be sth like 
      > http://youhost/...&map_layer_0_tolerance=1&map_layer_0_toleranceunits=feet
      > < http://youhost/...&map_layer_0_tolerance=1&map_layer_0_toleranceunits=feet>
      > (I don't know if the underscores in your layer name won't affect the
      > functionality so I'm assuming that it is the first layer in the 
      > mapfile and using the index of it). More information can be found on
      > http://mapserver.gis.umn.edu/docs/reference/cgi/controls in the very 
      > last chapter "Changing map file parameters via a form or a URL ".
      >
      > Hopefully it helps Marc with his issue.
      >
      > Regards,
      > Dmitri
      >
      > 2007/7/20, Bill Woodall < bwoodall at bwoodall.org
      > <mailto:bwoodall at bwoodall.org>>:
      >
      >     Hi All
      >
      >     What has worked for me in using TOLERANCE is to put it into the 
      >     mapfile
      >     ( if you are using MapServer) like ;
      >
      >         LAYER
      >             NAME Scrub_and_Chaparral
      >             TEMPLATE blank
      >             TOLERANCE 1
      >             TOLERANCEUNITS feet 
      >             METADATA
      >                 "wms_title" "Scrub_and_Chaparral"
      >                 "wms_include_items"  "CATEGORY,LEGEND,SOURCE"
      >             END 
      >             TYPE POLYGON
      >             STATUS ON
      >             DATA Scrub_and_Chaparral
      >
      >     ......Bill,
      >
      >     On Thu, 2007-07-19 at 20:08 +0200, Dmitri Mizerkin wrote:
      >     > Hi Marc,
      >     >
      >     > in a WMS/WFS service request the attribute you are looking for is
      >     > called TOLERANCE. I think this should do it when set as a
      >     parameter in 
      >     > getFullRequestString function (see user recipies:
      >     > http://trac.openlayers.org/wiki/GetFeatureInfo).
      >     >
      >     > Hopefully it helps you out. 
      >     >
      >     > Cheers,
      >     > Dmitri
      >     >
      >     > 2007/7/19, Marc Desharnais < marc.desharnais at ec.gc.ca
      >     <mailto: marc.desharnais at ec.gc.ca>>:
      >     >         Hi all,
      >     >
      >     >         I search for an attribute to set to make it easier to
      >     click on 
      >     >         points to
      >     >         get some info about them.
      >     >         I tried some things like RADIUS or REDIUS (saw that on a
      >     page
      >     >         on
      >     >         internet) but nothing works. 
      >     >
      >     >         I just want it to be easier to click on the point if it's
      >     >         possible, a
      >     >         couple of pixels more.
      >     >
      >     > 
      >     >         Thank in advance,
      >     >
      >     >         Marc
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