Determine if Point is in feature class attribute table

Question

I'm working with ArcObjects, C# and ArcMap. I have an attribute table that has several rows of data including a "shape" field that holds a point geometry. I also have a random point. How can I iterate through each point in the table to see if it matches my random point?

I thought using something like ISpatialFilter would work, but I'm not sure if I'm using it right. My code is below:

IPoint _point = new PointClass();
_point.PutCoords(3605857.580, 516199.563);
ISpatialFilter _filter = new SpatialFilterClass();
_filter.Geometry = _point;
_filter.GeometryField = _featureClass.ShapeFieldName;
_filter.SpatialRel = esriSpatialRelEnum.esriSpatialRelContains;
//_filter.WhereClause = "Shape = "+ _point+"";    // DONT KNOW WHAT TO PUT
//_filter.SubFields = "Shape";

IFeatureCursor _featureCursor = _featureClass.Search(_filter, false);

while ((_featureCursor.NextFeature()) != null)
     {
        if (_point == _featureCursor)
            {
               MessageBox.Show("FOUND");
            }
     }

As you can see, I do have some code edited out as I'm not sure what to put in certain areas.

Answer 1

Point on point isn't going to work, even if the coordinates are exact match, it's a 50/50 whether the feature class point will be selected by the query point. To overcome this I always buffer the point by a very small amount - this depends on your spatial reference, 1 metre (or foot) usually isn't very much but 1 degree usually is a very large number, you'll have to decide this yourself.

// new spatial filter class
ISpatialFilter pSpatialFilter = new SpatialFilterClass();
pSpatialFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelIntersects;

// buffer the point
ITopologicalOperator pTopOp = gSelectionPoint as ITopologicalOperator;
gSelectionGeom = pTopOp.Buffer(gSelectionDist); // gSelectionDist is a small number

// assign the buffer to the spatial filter
pSpatialFilter.Geometry = gSelectionGeom;

// check to see if this query matches *any* point in the table
if (_featureClass.FeatureCount(pSpatialFilter) > 0)
{
    // get the matching row(s)
    IFeatureCursor _featureCursor = _featureClass.Search(_filter, false);
}

Before you try to get any rows using a query filter you should get the feature count using IFeatureClass.FeatureCount, this is much quicker than actually grabbing the row(s) onto a cursor which can be of benefit if you want to do this lots of times.

As an aside, you're starting your variables with an underscore, I would encourage you not to do this as many system variables start with an underscore and you could get a name clash.. I use the pVariable, gVariable, cConstant syntax which immediately reveals the variables' scope p for local, g for global (try not to use many globals) and c for constant.