diff --git a/gtsam/geometry/Cal3_S2Stereo.h b/gtsam/geometry/Cal3_S2Stereo.h
index 7bbafd7d5..8282800c1 100644
--- a/gtsam/geometry/Cal3_S2Stereo.h
+++ b/gtsam/geometry/Cal3_S2Stereo.h
@@ -26,8 +26,10 @@ namespace gtsam {
 	 * @ingroup geometry
 	 * \nosubgrouping
 	 */
-	class Cal3_S2Stereo: public Cal3_S2 {
+	class Cal3_S2Stereo {
 	private:
+
+		Cal3_S2 K_;
 		double b_;
 
 	public:
@@ -39,12 +41,12 @@ namespace gtsam {
 
 		/// default calibration leaves coordinates unchanged
 		Cal3_S2Stereo() :
-			Cal3_S2(1, 1, 0, 0, 0), b_(1.0) {
+			K_(1, 1, 0, 0, 0), b_(1.0) {
 		}
 
 		/// constructor from doubles
 		Cal3_S2Stereo(double fx, double fy, double s, double u0, double v0, double b) :
-			Cal3_S2(fx, fy, s, u0, v0), b_(b) {
+			K_(fx, fy, s, u0, v0), b_(b) {
 		}
 
 		/// @}
@@ -52,23 +54,41 @@ namespace gtsam {
 		/// @{
 
 		void print(const std::string& s = "") const {
-			gtsam::print(matrix(), s);
-			std::cout << "Baseline: " << b_ << std::endl;
+			K_.print(s+"K: ");
+			std::cout << s << "Baseline: " << b_ << std::endl;
 		}
 
-    /// @}
+		/// Check if equal up to specified tolerance
+		bool equals(const Cal3_S2Stereo& other, double tol = 10e-9) const {
+			if (fabs(b_ - other.b_) > tol) return false;
+			return K_.equals(other.K_,tol);
+		}
+
+   /// @}
     /// @name Standard Interface
     /// @{
 
-		//TODO: remove?
-//		/**
-//		 * Check if equal up to specified tolerance
-//		 */
-//		bool equals(const Cal3_S2& K, double tol = 10e-9) const;
+		/// focal length x
+		inline double fx() const { return K_.fx();}
 
+		/// focal length x
+		inline double fy() const { return K_.fy();}
 
+		/// skew
+		inline double skew() const { return K_.skew();}
 
-		///TODO: comment
+		/// image center in x
+		inline double px() const { return K_.px();}
+
+		/// image center in y
+		inline double py() const { return K_.py();}
+
+		/// return the principal point
+		Point2 principalPoint() const {
+			return K_.principalPoint();
+		}
+
+		/// return baseline
 		inline double baseline() const { return b_; }
 
     /// @}
@@ -81,10 +101,8 @@ namespace gtsam {
 		template<class Archive>
 		void serialize(Archive & ar, const unsigned int version)
 		{
-			ar & boost::serialization::make_nvp("Cal3_S2Stereo",
-					boost::serialization::base_object<Value>(*this));
+			ar & BOOST_SERIALIZATION_NVP(K_);
 			ar & BOOST_SERIALIZATION_NVP(b_);
-			ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(Cal3_S2);
 		}
 		/// @}
 
diff --git a/gtsam/geometry/StereoCamera.h b/gtsam/geometry/StereoCamera.h
index f5e07e66c..4c278fab9 100644
--- a/gtsam/geometry/StereoCamera.h
+++ b/gtsam/geometry/StereoCamera.h
@@ -71,16 +71,6 @@ public:
 		return project(point, H1, H2);
 	}
 
-	/*
-	 * backproject using left camera calibration, up to scale only
-	 * i.e. does not rely on baseline
-	 */
-	Point3 backproject(const Point2& projection, const double scale) const {
-		Point2 intrinsic = K_->calibrate(projection);
-		Point3 cameraPoint = Point3(intrinsic.x() * scale, intrinsic.y() * scale, scale);;
-		return pose().transform_from(cameraPoint);
-	}
-
 	Point3 backproject(const StereoPoint2& z) const {
 		Vector measured = z.vector();
 		double Z = K_->baseline()*K_->fx()/(measured[0]-measured[1]);