[mapguide-users] Buffer is not working properly

[padmini godavarthi]

  Hi,
iam using mgos 2.1 with .net 2.0 on iis 6.0 

i have created a buffer layer .now i want to retrieve parcels with in the
buffer area.so i wrote a code.but the parcels were not properly retrieved 
from the bufferzone.
iam sending the screenshot of my application.

http://n2.nabble.com/file/n4578913/buffer.jpg 

In the list box i want to displaying the parcels that are in the buffer
zone.but it also contains the parcels from outside of the buffer area
too...............

Here is my code for retrieve parcels in the buffer area 

-------------------------------------------------------------------------------------------------------

Public Sub SelectBufferFeatures(ByVal LayerClassName As String, ByVal map As
MgMap, ByVal featureSrvc As MgFeatureService, ByVal sessionId As String,
ByVal mapWktSrs As String, ByVal srs As MgCoordinateSystem, ByVal srsMeasure
As MgCoordinateSystemMeasure)
      
        Dim selectedLayers As MgLayerCollection = map.GetLayers()
       
        Dim layer As MgLayer
        Dim featureGeometry As MgGeometry = Nothing
        Dim agfReaderWriter As MgAgfReaderWriter = New MgAgfReaderWriter()
        Dim queryOptions As MgFeatureQueryOptions = New
MgFeatureQueryOptions()
        For i As Integer = 0 To selectedLayers.GetCount() - 1
            layer = selectedLayers.GetItem(i)

            If (layer.GetName() = "PARCELS") Then
                Dim layerClassName1 As String = layer.GetFeatureClassName()
                Dim selectionString As String = ""
                selectionString = selection.GenerateFilter(layer,
LayerClassName)
                Dim LayerFeatureId As String = layer.GetFeatureSourceId()
                Dim layerFeatureResource As MgResourceIdentifier = New
MgResourceIdentifier(LayerFeatureId)

                queryOptions.SetFilter(selectionString)

                featureReader =
featureService.SelectFeatures(layerFeatureResource, layerClassName1,
queryOptions)
                Dim inputGeometries As MgGeometryCollection = New
MgGeometryCollection()
                
                While (featureReader.ReadNext())
                    Dim featureGeometryData As MgByteReader =
featureReader.GetGeometry("Geometry")
                    featureGeometry =
agfReaderWriter.Read(featureGeometryData)
                    inputGeometries.Add(featureGeometry)
                End While

                Dim geometryFactory As MgGeometryFactory = New
MgGeometryFactory()
                Dim mergedGeometries As MgMultiGeometry =
geometryFactory.CreateMultiGeometry(inputGeometries)
                Dim bufferDist As Double =
srs.ConvertMetersToCoordinateSystemUnits(bufferRingSize)

                bufferGeometry = mergedGeometries.Buffer(bufferDist,
srsMeasure)

                Dim queryOptions1 As MgFeatureQueryOptions = New
MgFeatureQueryOptions()

                queryOptions1.SetSpatialFilter("Geometry", bufferGeometry,
MgFeatureSpatialOperations.Within)
                queryOptions1.AddFeatureProperty("PARCEL")
                Dim featureReader1 As MgFeatureReader =
featureService.SelectFeatures(layerFeatureResource, layerClassName1,
queryOptions1)

                While (featureReader1.ReadNext())
                  
                    Dim value As String = featureReader1.GetString("PARCEL")
                    ListBox1.Items.Add(value)

                End While

                featureReader.Close()
              
                map.Save(resourceService)
            End If

        Next

    End Sub

where as bufferRingsize as double given by 500 


plz let me know why its happening like this.


Regards,
Padmini G.


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