Fix Loops or Knots.

Question

I need to find a way to remove Loops or Knots when a user saves a new edit.  These polygons that I create are sent to as boundries for images to be gathered and some are being rejected because of these self intersecting loops.  They are not self intersecting as they dont have self intersections as two vertices are added.  I need a way to either find the loop/knot or remove it automatically.  My removing self intersection code doesn't seem to fix this issue.  It appears I need to remove the loop entirely.

protected void RemoveSelfIntersections()
        {            
            try
            {
                Geometry originalShape = _dataInspector.Shape;
                if (!GeometryEngine.Instance.IsSimpleAsFeature(originalShape))
                {
                    Geometry intersectionShape = GeometryEngine.Instance.SimplifyAsFeature(originalShape, true);
                }
            }
            catch (Exception e)
            {

}

Anonymous User · Answer

Hi @MKa ,

This is my thought, if you want to remove inner white area from your geometry.

If you list the geometry rings from your polygon, there will be two rings from your example.

Anti-clockwise ring shall be inner white color ring and just remove it.

But for ArcGIS Pro sdk, I noticed that function GetExteriorRings of polygon. you may try and create polygon from these rings, I think this will remove inner white colour ring.

Best Regards,

MKa · Answer

I will give this a shot.  I think in my case two points can not share the same location.  So I could do this and flag the field.  I will try and implement something like this now and post my solution or what I came up with.

KirkKuykendall1 · Answer

Perhaps making a list of vertices with duplicate coordinates could be used for flagging. protected override async void OnClick() { try { var fLayer = MapView.Active?.GetSelectedLayers() .OfType() .Where(lyr => lyr.ShapeType == esriGeometryType.esriGeometryPolygon) .FirstOrDefault(); if (fLayer == null) return; await QueuedTask.Run(() => { using (var sel = fLayer.GetSelection()) using (var cur = sel.Search()) { if (cur.MoveNext()) { using (var feat = cur.Current as Feature) { var list = GetSelfIntersects(feat.GetShape() as Polygon); Debug.Print($"{list.Count} duplicate vertices"); } } } }); } catch(Exception ex) { Debug.Print(ex.Message); } } private List GetSelfIntersects(Polygon polygon) { // assumes vertices have been snapped // (skip this first point, since it will coincide with last point) return polygon.Points.Skip(1) // could round here to cluster //.GroupBy(pnt => (Math.Round(pnt.X,2),Math.Round(pnt.Y,2)) .GroupBy(pnt => (pnt.X, pnt.Y)) // could round here to cluster .Where(g => g.Count() > 1) .Select(g => { var sr = polygon.SpatialReference; return MapPointBuilder.CreateMapPoint(g.Key.X, g.Key.Y, sr); }) .ToList(); }