private void WpfMap_Loaded(object sender, RoutedEventArgs e)
        {
            Map1.MapUnit = GeographyUnit.DecimalDegree;
            Map1.CurrentExtent = new RectangleShape(-155.733, 95.60, 104.42, -81.9);

            InMemoryFeatureLayer wellsOnBottom = new InMemoryFeatureLayer();
            wellsOnBottom.ZoomLevelSet.ZoomLevel01.DefaultPointStyle = PointStyles.Capital1;
            wellsOnBottom.ZoomLevelSet.ZoomLevel01.ApplyUntilZoomLevel = ApplyUntilZoomLevel.Level20;
            wellsOnBottom.InternalFeatures.Add(new Feature(0, 0));
            wellsOnBottom.InternalFeatures.Add(new Feature(18, 3));

            InMemoryFeatureLayer wellsOnTop = new InMemoryFeatureLayer();
            wellsOnTop.ZoomLevelSet.ZoomLevel01.DefaultPointStyle = new MyPointStyle(new GeoFont("Arial", 12), 177, new GeoSolidBrush(GeoColor.StandardColors.Black)) { wellsBottom=wellsOnBottom};
            wellsOnTop.ZoomLevelSet.ZoomLevel01.ApplyUntilZoomLevel = ApplyUntilZoomLevel.Level20;
            wellsOnTop.InternalFeatures.Add(new Feature(0, 0));
            wellsOnTop.InternalFeatures.Add(new Feature(20, 5));

            LayerOverlay ov = new LayerOverlay(new Collection<InMemoryFeatureLayer>() { wellsOnBottom, wellsOnTop });
            Map1.Overlays.Add(ov);
            Map1.Refresh();

        }

        class MyPointStyle : PointStyle
        {
            public MyPointStyle(GeoFont characterFont, int characterIndex, GeoSolidBrush characterSolidBrush)
                : base(characterFont, characterIndex, characterSolidBrush)
            { }

            public InMemoryFeatureLayer wellsBottom;

            protected override void DrawCore(System.Collections.Generic.IEnumerable<Feature> features, GeoCanvas canvas, System.Collections.ObjectModel.Collection<SimpleCandidate> labelsInThisLayer, System.Collections.ObjectModel.Collection<SimpleCandidate> labelsInAllLayers)
            {
                Collection<Feature> featuresToDraw = new Collection<Feature>();
                foreach (Feature feature in features)
                {
                    if (wellsBottom.FeatureSource.GetFeaturesInsideBoundingBox(feature.GetShape().Buffer(0.1, GeographyUnit.DecimalDegree, DistanceUnit.Kilometer).GetBoundingBox(), ReturningColumnsType.NoColumns).Count==0)
                    {
                        featuresToDraw.Add(feature);
                    }
                }
                    base.DrawCore(featuresToDraw, canvas, labelsInThisLayer, labelsInAllLayers);
            }
        }