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I would expect ISpatialFilter.SpatialRelDescription to behave consistently with IRelationalOperator.Relation. However, when I run the code below, I get:

    Total features : 44368
    Count1: 9 T********
    Count2: 9 T********
    Count1: 21 F********
    Count2: 44359 F********
    Count1: 1 ******F**
    Count2: 1 ******F**

Is this a bug in the F******** relation ?

private void TestSpatialFilter()
    IMxDocument mxdoc = ((IApplication)m_application).Document as IMxDocument;
    IFeatureLayer fLayer = mxdoc.FocusMap.get_Layer(0) as IFeatureLayer;
    IEnvelope env = ((IActiveView)mxdoc.FocusMap).Extent;
    env.Expand(0.5, 0.5, true);
    Debug.Print("Total features : {0}", fLayer.FeatureClass.FeatureCount(null));
    IFeatureClass fc = fLayer.FeatureClass;
    string[] rels = { "T********", "F********", "******F**" };
    foreach (string rel in rels)
        Debug.Print("Count1: {0} {1}", Count1(fc, env, rel), rel);
        Debug.Print("Count2: {0} {1}", Count2(fc, env, rel), rel);

public static int Count1(IFeatureClass fc, IGeometry geom,  string relDescription)
    ISpatialFilter sf = new SpatialFilterClass();
    sf.SpatialRel = esriSpatialRelEnum.esriSpatialRelRelation;
    sf.SpatialRelDescription = relDescription;
    sf.Geometry = geom;
    int i = fc.FeatureCount(sf);
    return i;
public static int Count2(IFeatureClass fc, IGeometry geom, string relDescription)
    int i = 0;
    string relation = String.Format("RELATE(G1,G2,'{0}')", relDescription);
    IRelationalOperator relOp = geom as IRelationalOperator;

    IFeatureCursor fCur = fc.Search(null, false);
    IFeature feat;
    while ((feat = fCur.NextFeature()) != null)
    return i;
share|improve this question
sorry, no answer but +1 for the geospatial humor – bFlood Aug 12 '10 at 14:14
up vote 2 down vote accepted

That does seem a bit odd. Perhaps it was only tested with few specific operations, Ex: Intersects, Disjoint, etc? What does FF*FF**** (inverse of T********) do for you? I seem to remember Within not working a few versions back so it does not surprise me.

share|improve this answer
That seems to work. If spatial is so special, it sure seems like it should receive better QA. – Kirk Kuykendall Aug 31 '10 at 17:48

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