Spatial Query between polyline features and point features within specified Buffer

Question

I'm new to GIS (so I'm lost on this) and looking for a C# code sample to help me do 2 types of spatial queries. I have 2 Layers only. First layer is pipelines, which are polyline shapes so I can select multiple pipeline segments to make up an entire pipeline. Second Layer is facilities, which are point shapes.

Query 1: Select Pipeline Segments in the Pipeline Layer (Polylines) and find the facilities (in the Facility Layer) that are within a certain distance of selected Pipeline Segments.

Query 2: Select a single Facility in the Facility Layer (Point) and find the Pipeline Segments (Polylines) that are within a certain distance of the Facility Point.

I can do these queries via the ArcMap interface. I select the Source Features in the Attribute Table, then Selection Menu, Select by Location, select the "other" Layer as the Target Layer and for Spatial Selection Method I select "Target layer(s) features are within a distance of the Source layer feature". But now I need to do this in C# code for my ArcMap AddIn.

Answer 1

Assuming you have a handle of your query featureclass and selected feature, you can use the following code snippet:

double searchDistance = 10; //this is your buffer distance
IFeatureClass fc = ...; //Query1: this is your facility feature class
IFeature feat = ...;// Query1: this is your selected pipeline feature

ISpatialFilter spatialFilter = new SpatialFilterClass();
if (searchDistance == 0)
    spatialFilter.Geometry = feat.Shape; // can be IGeometry
else
{
    ITopologicalOperator topoOperator = (ITopologicalOperator)feat.ShapeCopy;
    spatialFilter.Geometry = topoOperator.Buffer(searchDistance);
}

spatialFilter.GeometryField = fc.ShapeFieldName;
spatialFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelIntersects;

IFeatureCursor featureCursor = fc.Search(spatialFilter, true);

//loop through features in the cursor

Answer 2

This was what I did to solve the problem. Some of it might need to be explained but I think it's very clear. Thanks to brenth. https://gis.stackexchange.com/users/19213/brenth

This helped a lot! Selecting features by location based on selected feature using ArcObjects?

   public void GetClosestFeatures(IEnumerable selectedFeatures)
   {
    try
    {
        var mxDocument = ArcMap.Application.Document as IMxDocument;
        if (mxDocument != null)
        {
            var map = mxDocument.FocusMap;
            var searchDistance = 1000.0;

            if(UI.LayerSelection.Equals("Pipeline"))
            {
                if (UI.txtRadiusToFacilities.Text != "")
                {
                    searchDistance = Convert.ToDouble(UI.txtRadiusToFacilities.Text);
                }
                else
                {
                    UI.txtRadiusToFacilities.Text = searchDistance.ToString(CultureInfo.InvariantCulture);
                }

                // This not 100% Accurate due to the Lattitude changing as you move north/south so if we know the lattite we can use
                // the MetersToDecimalDegrees function but this will do!
                searchDistance = Convert.ToDouble((UI.txtRadiusToFacilities.Text)) / (111.32 * 1000); 
            }
            else
            {
                if (UI.txtRadiusToPipelines.Text != "")
                {
                    searchDistance = Convert.ToDouble(UI.txtRadiusToPipelines.Text);
                }
                else
                {
                    UI.txtRadiusToPipelines.Text = searchDistance.ToString(CultureInfo.InvariantCulture);
                }

                // This not 100% Accurate due to the Lattitude changing as you move north/south so if we know the lattite we can use
                // the MetersToDecimalDegrees function but this will do!
                searchDistance = Convert.ToDouble((UI.txtRadiusToPipelines.Text)) / (111.32 * 1000); 
            }

            var cursor = GetSelectedFeatures(CurrentLayer);
            // Default buffer is Decimal Degrees
            var polygon = UnionShapes(cursor, searchDistance);

            // Maybe use the name in place of the CurrentLayer.Name as this is to find Facilities for the Selected Pipelines
            var featureLayer = Utilities.GetOppositeFeatureLayerByFeatureClassName(map, CurrentLayer.Name);
            var filter = CreateSpatialFilter(featureLayer.FeatureClass, polygon);
            var cursor2 = GetSelectedItemsByShape(featureLayer.FeatureClass, filter);

            // Iterate through the features, viewing (as in this case) or editing them.
            IFeatureClass fc = Utilities.GetOppositeFeatureLayerByFeatureClassName(map, CurrentLayer.Name).FeatureClass;
            IFeature feature = null;

            if (UI.LayerSelection.Equals("Pipeline"))
            {
                var nameFacilityNameIndex = fc.Fields.FindField(GeodatabaseFieldNames.FacilityNameFieldName);
                var nameFacilityTypeIndex = fc.Fields.FindField(GeodatabaseFieldNames.FacilityTypeFieldFieldName);
                var counter = 0;
                UI.lvwFacilitiesSpatialResult.Items.Clear();
                try
                {
                    while ((feature = cursor2.NextFeature()) != null)
                    {
                        //Console.WriteLine("Facility Found: {0}", feature.get_Value(nameFieldIndex));
                        counter++;
                        string[] rowData =
                            {
                                (counter).ToString(CultureInfo.InvariantCulture),
                                feature.get_Value(nameFacilityNameIndex).ToString(),
                                feature.get_Value(nameFacilityTypeIndex).ToString()
                            };
                        var lvItem = new ListViewItem(rowData);
                        UI.lvwFacilitiesSpatialResult.Items.Add(lvItem);
                    }
                }
                catch (Exception ex)
                {
                    // Handle any errors that might occur on NextFeature().
                    MessageBox.Show(ex.Message, @"Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                }                            
            }
            else // Facility
            {
                var namePipelinenameIndex = fc.Fields.FindField(GeodatabaseFieldNames.PipelineNameFieldName);
                var companyNameFieldIndex = fc.Fields.FindField(GeodatabaseFieldNames.OperatorNameFieldName);
                var counter = 0;
                UI.lvwPipelinesSpatialResult.Items.Clear();
                try
                {
                    while ((feature = cursor2.NextFeature()) != null)
                    {
                        //Console.WriteLine("Facility Found: {0}", feature.get_Value(nameFieldIndex));
                        counter++;
                        string[] rowData =
                            {
                                (counter).ToString(CultureInfo.InvariantCulture),
                                feature.get_Value(namePipelinenameIndex).ToString(),
                                feature.get_Value(companyNameFieldIndex).ToString()
                            };
                        var lvItem = new ListViewItem(rowData);
                        UI.lvwPipelinesSpatialResult.Items.Add(lvItem);
                    }
                }
                catch (Exception ex)
                {
                    // Handle any errors that might occur on NextFeature().
                    MessageBox.Show(ex.Message, @"Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                }
            }
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message, @"Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
    }

}

public static IFeatureCursor GetSelectedFeatures(IFeatureLayer featureLayer)
{
    if (featureLayer == null) return null;
    IFeatureSelection fSel = (IFeatureSelection)featureLayer;
    ISelectionSet selSet = (ISelectionSet)fSel.SelectionSet;
    ICursor cursor = null;
    selSet.Search(null, false, out cursor);
    IFeatureCursor fCursor = cursor as IFeatureCursor;
    return fCursor;
}

public static IPolygon UnionShapes(IFeatureCursor cursor, double bufferDist)
{
    if (cursor == null) return null;
    IFeature pFeat = cursor.NextFeature();
    if (pFeat != null)
    {
        if (pFeat.Shape is IPoint || pFeat.Shape is IPolyline)
        {
            ITopologicalOperator ptopBuffer = (ITopologicalOperator)pFeat.Shape;
            IPolygon pTempPoly = (IPolygon)ptopBuffer.Buffer(bufferDist);
            ITopologicalOperator ptopUnion = (ITopologicalOperator)pTempPoly;
            pFeat = cursor.NextFeature();
            while (pFeat != null)
            {
                ptopBuffer = (ITopologicalOperator)pFeat.Shape;
                pTempPoly = (IPolygon)ptopBuffer.Buffer(bufferDist);
                ptopUnion = (ITopologicalOperator)ptopUnion.Union(pTempPoly);
                pFeat = cursor.NextFeature();
            }
            return (IPolygon)ptopUnion;
        }
        return null;
    }
    return null;
}

public static ISpatialFilter CreateSpatialFilter(IFeatureClass fc, IGeometry shape)
{
    if (fc == null) return null;

    ISpatialFilter sf = new SpatialFilterClass();
    sf.GeometryField = fc.ShapeFieldName;
    sf.Geometry = shape;
    sf.SpatialRel = esriSpatialRelEnum.esriSpatialRelIntersects;

    return sf;
}

public static IFeatureCursor GetSelectedItemsByShape(IFeatureClass fc, ISpatialFilter filter)
{
    try
    {
        if (filter == null) return null;
        if (fc == null) return null;
        IFeatureCursor fcursor = fc.Search(filter, true);
        return fcursor;
    }
    catch
    {
        return null;
    }
}

public static ISelectionSet CursorToSelectionSet(IFeatureLayer layer, IFeatureCursor cursor)
{

    IFeatureSelection fSel = (IFeatureSelection)layer;
    if (cursor != null)
    {
        IFeature feat = cursor.NextFeature();
        while (feat != null)
        {
            fSel.Add(feat);
            feat = cursor.NextFeature();
        }
    }
    return fSel.SelectionSet;
}

Since I only have 2 Layers then I can do this.

public static IFeatureLayer GetOppositeFeatureLayerByFeatureClassName(IMap map, string featureClassName) { IFeatureLayer result = null; for (var i = 0; i