diff --git a/MapControl/MapPath.WPF.cs b/MapControl/MapPath.WPF.cs
index c02af5ba..4bb4c14a 100644
--- a/MapControl/MapPath.WPF.cs
+++ b/MapControl/MapPath.WPF.cs
@@ -11,8 +11,8 @@ namespace MapControl
     public partial class MapPath : Shape
     {
         public static readonly DependencyProperty DataProperty = DependencyProperty.Register(
-            "Data", typeof(Geometry), typeof(MapPath),
-            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender));
+            "Data", typeof(Geometry), typeof(MapPath), new FrameworkPropertyMetadata(
+                null, FrameworkPropertyMetadataOptions.AffectsRender, (o, e) => ((MapPath)o).UpdateData()));
 
         public Geometry Data
         {
diff --git a/MapControl/MapPath.cs b/MapControl/MapPath.cs
index 665b3016..17fa8c80 100644
--- a/MapControl/MapPath.cs
+++ b/MapControl/MapPath.cs
@@ -4,14 +4,17 @@
 
 #if WINDOWS_RUNTIME
 using Windows.Foundation;
+using Windows.UI.Xaml.Media;
 #else
 using System.Windows;
+using System.Windows.Media;
 #endif
 
 namespace MapControl
 {
     /// <summary>
-    /// Base class for map shapes.
+    /// Base class for map shapes. The shape geometry is given by the Data property,
+    /// which must contain a Geometry defined in cartesian (projected) map coordinates.
     /// </summary>
     public partial class MapPath : IMapElement
     {
@@ -29,6 +32,17 @@ namespace MapControl
 
         protected virtual void UpdateData()
         {
+            if (Data != null)
+            {
+                if (parentMap != null)
+                {
+                    Data.Transform = ParentMap.ViewportTransform;
+                }
+                else
+                {
+                    Data.ClearValue(Geometry.TransformProperty);
+                }
+            }
         }
 
         protected override Size MeasureOverride(Size constraint)
diff --git a/MapControl/MapPolyline.Silverlight.WinRT.cs b/MapControl/MapPolyline.Silverlight.WinRT.cs
index 6a9d8df4..532d1678 100644
--- a/MapControl/MapPolyline.Silverlight.WinRT.cs
+++ b/MapControl/MapPolyline.Silverlight.WinRT.cs
@@ -21,37 +21,32 @@ namespace MapControl
         protected override void UpdateData()
         {
             var geometry = (PathGeometry)Data;
-            var locations = Locations;
-            Location first;
+            geometry.Figures.Clear();
 
-            if (ParentMap != null && locations != null && (first = locations.FirstOrDefault()) != null)
+            if (ParentMap != null && Locations != null && Locations.Any())
             {
+                var points = Locations.Select(l => ParentMap.MapTransform.Transform(l));
+
                 var figure = new PathFigure
                 {
-                    StartPoint = ParentMap.MapTransform.Transform(first),
+                    StartPoint = points.First(),
                     IsClosed = IsClosed,
                     IsFilled = IsClosed
                 };
 
                 var segment = new PolyLineSegment();
 
-                foreach (var location in locations.Skip(1))
+                foreach (var point in points.Skip(1))
                 {
-                    segment.Points.Add(ParentMap.MapTransform.Transform(location));
+                    segment.Points.Add(point);
                 }
 
-                if (segment.Points.Count > 0)
-                {
-                    figure.Segments.Add(segment);
-                }
-
-                geometry.Figures.Clear();
+                figure.Segments.Add(segment);
                 geometry.Figures.Add(figure);
                 geometry.Transform = ParentMap.ViewportTransform;
             }
             else
             {
-                geometry.Figures.Clear();
                 geometry.ClearValue(Geometry.TransformProperty);
             }
         }
diff --git a/MapControl/MapPolyline.WPF.cs b/MapControl/MapPolyline.WPF.cs
index 4cb7970e..2ae660cf 100644
--- a/MapControl/MapPolyline.WPF.cs
+++ b/MapControl/MapPolyline.WPF.cs
@@ -17,18 +17,15 @@ namespace MapControl
         protected override void UpdateData()
         {
             var geometry = (StreamGeometry)Data;
-            var locations = Locations;
-            Location first;
 
-            if (ParentMap != null && locations != null && (first = locations.FirstOrDefault()) != null)
+            if (ParentMap != null && Locations != null && Locations.Any())
             {
                 using (var context = geometry.Open())
                 {
-                    var startPoint = ParentMap.MapTransform.Transform(first);
-                    var points = locations.Skip(1).Select(l => ParentMap.MapTransform.Transform(l)).ToList();
+                    var points = Locations.Select(l => ParentMap.MapTransform.Transform(l));
 
-                    context.BeginFigure(startPoint, IsClosed, IsClosed);
-                    context.PolyLineTo(points, true, false);
+                    context.BeginFigure(points.First(), IsClosed, IsClosed);
+                    context.PolyLineTo(points.Skip(1).ToList(), true, false);
                 }
 
                 geometry.Transform = ParentMap.ViewportTransform;
diff --git a/MapControl/MapRectangle.cs b/MapControl/MapRectangle.cs
index ed168e0c..2cbd2c37 100644
--- a/MapControl/MapRectangle.cs
+++ b/MapControl/MapRectangle.cs
@@ -34,12 +34,13 @@ namespace MapControl
             "North", typeof(double), typeof(MapRectangle),
             new PropertyMetadata(double.NaN, (o, e) => ((MapRectangle)o).UpdateData()));
 
-        private bool boundingBoxValid = true;
+        private bool boundingBoxValid;
 
         public MapRectangle()
         {
-            Data = new RectangleGeometry();
             StrokeThickness = 0d;
+            Data = new RectangleGeometry();
+            boundingBoxValid = true;
         }
 
         public double West