AW: AW: Re: Fwd: [Qgis-user] QGIS "Near"

Fri Oct 22 00:19:49 PDT 2010

Hi

there is some strange behaviour when using it with polygon features (at least I think it's a bit strange): sometimes when you click into a polygon I would expect that it selects the polygon I clicked into but it selects an adjacent polygon. This is probably due to the nearestNeighbor method of the spatial index. Since the two neighboring polygons share a common border the distance would be equal but the spatial index does not check if the coordindates of the mouse click lies within one of the two polygons.

regards
Stefan

mit freundlichem Gruss
Stefan Ziegler

----- Originalnachricht -----
Von: "Jim Hammack" <hammack at GotSlack.org>
Gesendet: Don, 21.10.2010 19:20
An: "Ziegler Stefan" <Stefan.Ziegler at bd.so.ch>
Cc: qgis-user <qgis-user at lists.osgeo.org>
Betreff: Re: AW: Re: Fwd: [Qgis-user] QGIS "Near"

    Stefan,

             I was looking for the same functionality as Zoran so have
        also been working with your "Nearest" plugin.  It is exactly
        what I need and seems to work well.

                                                                Thanks!

                                                                    Jim

    On 10/20/2010 01:54 PM, Ziegler Stefan wrote:

      Hi Zoran

      I had some time left, took all
            my code snippets and also the one from Carson. Please try
            the plugin "Nearest" that should cover your example 1:

      http://www.catais.org/qgis/plugins.xml

      regards

      Stefan

        -----Ursprüngliche
            Nachricht-----

            Von: Zoran Jankovic [mailto:zoran.jankovic at zisis.hr]

            Gesendet am: Mittwoch, 20. Oktober 2010 19:21

            An: qgis-user

            Betreff: Re: Fwd: [Qgis-user] QGIS "Near"

          Hi Joe, 

          On Wed, Oct 20, 2010 at 5:06 PM, Joe
            Larson <joelarso at gmail.com>
            wrote:

              Does the function 'snapWithContext'

              http://doc.qgis.org/head/classQgsVectorLayer.html#733b974dce13d587e05cf3d4fc24f208

              which "Snaps to segment or vertex within given tolerance."
              seem like

              what you're looking for? I came across it while trying to
              get Quantum

              Navigator working recently...seemed relative, but I'm no
              expert!

            This is similar to the mentioned solution with
              selecting by radius, or changing the tolerance of ID tool.
              Close, but no cigar. Since this is not very urgent, I've
              decided to continue pursuing that outlined solution Carson
              gave, and write a plugin i Python based on that. Since I
              actually never used Python before, it may take a while,
              but hey, I get to learn sth. new :-).

            I never got the word back from Carson, has he developed
              anything along these lines, but I have to presume he
              didn't...

            Anyone interested in joning me, or even earning some
              money, is still invited to jump on board. My GIS
              implementation project is well on the way, and it seems
              there'll even be some money involved :-). 

            Zoran

              ~joe

              On Tue, Oct 19, 2010 at 9:55 AM, Andreas Neumann
              <a.neumann at carto.net>wrote:

                  > Hi Zoran,

                  >

                  > I believe the infrastructure of what you want is
                  already wihtin the

                  > selection and identify tools in QGIS. Isn't this
                  almost implemented in the

                  > current identify tool?

                  >

                  >

                  It sort of is, but not completely. Identify will ID
                  all the features within

                  certain radios (percentage of extent), but it will ID
                  _all_ of the features

                  within this radius. I only need the nearest, no matter
                  how far away... Let

                  us say it is, for simplicity, within current extent.

                  > The current identify tool selects "near" or
                  "close by" features within a

                  > certain tolerance. This tolerance can be set in
                  "Options" --> "Map tools"

                  > "search radius". I believe it currently only
                  effects the identify tool. Do

                  > you want the same tolerance also be used for the
                  click-selection tool?

                  >

                  >

                  Look above. This could be useful, but it is not the
                  functionality I'm

                  currently looking after.

                  > Are you also aware that in QGIS 1.6 there are new
                  selection tools?

                  >

                  > * by click

                  > * by rectangle

                  > * by polygon

                  > * by freehand

                  > * by radius

                  >

                  >

                  Yup, these are great, but they all select _multiple_
                  features within radius,

                  rectangle, etc.

                  > Maybe this also helps to address your needs?

                  >

                  > Of course you can combine it with previous
                  selections by pressing the ctrl

                  > key.

                  >

                  >

                  BR,

                  ---

                  Zoran Jankovic

                  ZIS-Izrada softvera i savjetovanje / ZIS - Software
                  Development and

                  Consulting

                  http://www.zisis.hr

                  M: 00 385 98 682 902

                  T:  00 385 44 683 374

                  A. Senoe 4

                  44320 Kutina

                  Croatia

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