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.

• artwork21: key words to search "arcobjects query select distance", you should find many code examples
• Farid Cheraghi: @Dave Stuart, You should use spatail filter with arcobjects. Take a look at How to execute spatial queries and try to create some sample code and include more details in your question
• Dave Stuart: Thanks @Farid Cher but I have searched high and low and visited that link several times. I thought my question is very clear for a GIS developer to answer with a pseudo code example.

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

• Dave Stuart: Thanks Farid. I tried this a couple days ago and got some sort of result but it was not what I expected so I will have to look at it again on Monday. Thanks for the code sample though as it has helped. I mark this one UP if I can get the correct results.
• Farid Cheraghi: We could discuss about the issues you are facing, here!
• Dave Stuart: My code returns the same Facilities no matter what Pipeline I Select. In your code sample where would I actually use Selected Features from the Pipeline? I'm using IFeature feat = CurrentLayer.FeatureClass.GetFeature(1); to get the Set the Currently selected layer but these is no mention of the actual selected Pipeline rows. I think that is where I'm going wrong?
• Dave Stuart: I think my question was quite clear that I was selecting Pipeline features (rows in the Pipeline attribute table) and wanted to run a Spatial Query against the Facilities Layer to get the closest Facilities to those selected Pipelines. I have however figured out the solution using this post. gis.stackexchange.com/questions/112018/….

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