diff --git a/MapControl/Shared/BoundingBox.cs b/MapControl/Shared/BoundingBox.cs
index eef8c479..61b244fa 100644
--- a/MapControl/Shared/BoundingBox.cs
+++ b/MapControl/Shared/BoundingBox.cs
@@ -16,9 +16,7 @@ namespace MapControl
     public class BoundingBox
     {
         private double south;
-        private double west;
         private double north;
-        private double east;
 
         public BoundingBox()
         {
@@ -32,48 +30,40 @@ namespace MapControl
             East = east;
         }
 
+        public double West { get; set; }
+
+        public double East { get; set; }
+
         public double South
         {
             get { return south; }
             set { south = Math.Min(Math.Max(value, -90d), 90d); }
         }
 
-        public double West
-        {
-            get { return west; }
-            set { west = value; }
-        }
-
         public double North
         {
             get { return north; }
             set { north = Math.Min(Math.Max(value, -90d), 90d); }
         }
 
-        public double East
-        {
-            get { return east; }
-            set { east = value; }
-        }
-
         public virtual double Width
         {
-            get { return east - west; }
+            get { return East - West; }
         }
 
         public virtual double Height
         {
-            get { return north - south; }
+            get { return North - South; }
         }
 
         public bool HasValidBounds
         {
-            get { return south < north && west < east; }
+            get { return South < North && West < East; }
         }
 
         public virtual BoundingBox Clone()
         {
-            return new BoundingBox(south, west, north, east);
+            return new BoundingBox(South, West, North, East);
         }
 
         public static BoundingBox Parse(string s)
diff --git a/MapControl/Shared/MapPanel.cs b/MapControl/Shared/MapPanel.cs
index 52ef6a20..6e1db748 100644
--- a/MapControl/Shared/MapPanel.cs
+++ b/MapControl/Shared/MapPanel.cs
@@ -244,13 +244,14 @@ namespace MapControl
 
             if (parentMap != null)
             {
-                pos = parentMap.MapProjection.LocationToViewportPoint(location);
+                var projection = parentMap.MapProjection;
+                pos = projection.LocationToViewportPoint(location);
 
-                if (parentMap.MapProjection.IsCylindrical &&
+                if (projection.IsCylindrical &&
                     (pos.X < 0d || pos.X > parentMap.RenderSize.Width ||
                      pos.Y < 0d || pos.Y > parentMap.RenderSize.Height))
                 {
-                    pos = parentMap.MapProjection.LocationToViewportPoint(new Location(
+                    pos = projection.LocationToViewportPoint(new Location(
                         location.Latitude,
                         Location.NearestLongitude(location.Longitude, parentMap.Center.Longitude)));
                 }
@@ -310,7 +311,7 @@ namespace MapControl
                 var center = new Point(rect.X + rect.Width / 2d, rect.Y + rect.Height / 2d);
                 var pos = projection.ViewportTransform.Transform(center);
 
-                if (parentMap.MapProjection.IsCylindrical &&
+                if (projection.IsCylindrical &&
                     (pos.X < 0d || pos.X > parentMap.RenderSize.Width ||
                      pos.Y < 0d || pos.Y > parentMap.RenderSize.Height))
                 {
diff --git a/MapControl/Shared/MapProjection.cs b/MapControl/Shared/MapProjection.cs
index 880559e9..41ddcf19 100644
--- a/MapControl/Shared/MapProjection.cs
+++ b/MapControl/Shared/MapProjection.cs
@@ -25,8 +25,6 @@ namespace MapControl
         public const double Wgs84EquatorialRadius = 6378137d;
         public const double MetersPerDegree = Wgs84EquatorialRadius * Math.PI / 180d;
 
-        private Matrix inverseViewportTransformMatrix;
-
         /// <summary>
         /// Gets or sets the WMS 1.3.0 CRS Identifier.
         /// </summary>
@@ -58,6 +56,11 @@ namespace MapControl
         /// </summary>
         public Matrix ViewportTransform { get; private set; }
 
+        /// <summary>
+        /// Gets the transform matrix from viewport coordinates to cartesian map coordinates (pixels).
+        /// </summary>
+        public Matrix InverseViewportTransform { get; private set; }
+
         /// <summary>
         /// Gets the scaling factor from cartesian map coordinates to viewport coordinates.
         /// </summary>
@@ -115,7 +118,7 @@ namespace MapControl
         /// </summary>
         public Location ViewportPointToLocation(Point point)
         {
-            return PointToLocation(inverseViewportTransformMatrix.Transform(point));
+            return PointToLocation(InverseViewportTransform.Transform(point));
         }
 
         /// <summary>
@@ -123,7 +126,7 @@ namespace MapControl
         /// </summary>
         public BoundingBox ViewportRectToBoundingBox(Rect rect)
         {
-            var transform = new MatrixTransform { Matrix = inverseViewportTransformMatrix };
+            var transform = new MatrixTransform { Matrix = InverseViewportTransform };
 
             return RectToBoundingBox(transform.TransformBounds(rect));
         }
@@ -139,9 +142,8 @@ namespace MapControl
             var matrix = CreateTransformMatrix(center, ViewportScale, -ViewportScale, heading, viewportCenter);
 
             ViewportTransform = matrix;
-
             matrix.Invert();
-            inverseViewportTransformMatrix = matrix;
+            InverseViewportTransform = matrix;
         }
 
         /// <summary>
diff --git a/MapControl/WPF/XmlDocument.WPF.cs b/MapControl/WPF/XmlDocument.WPF.cs
index cd50e016..9249453a 100644
--- a/MapControl/WPF/XmlDocument.WPF.cs
+++ b/MapControl/WPF/XmlDocument.WPF.cs
@@ -7,7 +7,7 @@ using System.Threading.Tasks;
 
 namespace MapControl
 {
-    public class XmlDocument : System.Xml.XmlDocument
+    internal class XmlDocument : System.Xml.XmlDocument
     {
         public static XmlDocument LoadFromUri(Uri uri)
         {