diff --git a/sprout/darkroom/cameras.hpp b/sprout/darkroom/cameras.hpp
index 21a49a25..83f5d274 100644
--- a/sprout/darkroom/cameras.hpp
+++ b/sprout/darkroom/cameras.hpp
@@ -2,6 +2,7 @@
 #define SPROUT_DARKROOM_CAMERAS_HPP
 
 #include <sprout/config.hpp>
+#include <sprout/darkroom/cameras/angle_of_view.hpp>
 #include <sprout/darkroom/cameras/simple_camera.hpp>
 
 #endif	// #ifndef SPROUT_DARKROOM_CAMERAS_HPP
diff --git a/sprout/darkroom/cameras/angle_of_view.hpp b/sprout/darkroom/cameras/angle_of_view.hpp
new file mode 100644
index 00000000..427668d1
--- /dev/null
+++ b/sprout/darkroom/cameras/angle_of_view.hpp
@@ -0,0 +1,27 @@
+#ifndef SPROUT_DARKROOM_CAMERAS_ANGLE_OF_VIEW_HPP
+#define SPROUT_DARKROOM_CAMERAS_ANGLE_OF_VIEW_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/tuple/tuple.hpp>
+#include <sprout/darkroom/coords/vector.hpp>
+
+namespace sprout {
+	namespace darkroom {
+		namespace cameras {
+			//
+			// angle_of_view_reference
+			//
+			struct angle_of_view_reference {
+			public:
+				enum values {
+					long_side,
+					short_side,
+					width,
+					height
+				};
+			};
+		}	// namespace cameras
+	}	// namespace darkroom
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_DARKROOM_CAMERAS_ANGLE_OF_VIEW_HPP
diff --git a/sprout/darkroom/cameras/simple_camera.hpp b/sprout/darkroom/cameras/simple_camera.hpp
index afbed2ff..bb3e057d 100644
--- a/sprout/darkroom/cameras/simple_camera.hpp
+++ b/sprout/darkroom/cameras/simple_camera.hpp
@@ -1,31 +1,134 @@
 #ifndef SPROUT_DARKROOM_CAMERAS_SIMPLE_CAMERA_HPP
 #define SPROUT_DARKROOM_CAMERAS_SIMPLE_CAMERA_HPP
 
+#include <cmath>
 #include <sprout/config.hpp>
 #include <sprout/tuple/tuple.hpp>
 #include <sprout/darkroom/coords/vector.hpp>
+#include <sprout/darkroom/cameras/angle_of_view.hpp>
 
 namespace sprout {
 	namespace darkroom {
 		namespace cameras {
-			template<typename Unit = double>
+			//
+			// basic_simple_camera
+			//
+			template<typename Unit = double, typename Position = sprout::tuples::tuple<Unit, Unit, Unit> >
 			class basic_simple_camera {
 			public:
 				typedef Unit unit_type;
-				typedef sprout::tuples::tuple<unit_type, unit_type, unit_type> position_type;
+				typedef Position position_type;
 				typedef sprout::tuples::tuple<position_type, position_type> ray_type;
+				typedef sprout::darkroom::cameras::angle_of_view_reference angle_of_view_reference;
 			private:
 				unit_type far_plane_;
+				angle_of_view_reference::values reference_value_;
+				position_type position_;
+				position_type fixation_point_;
+				unit_type rotate_;
+			private:
+				SPROUT_CONSTEXPR position_type transform_1(
+					position_type const& c,
+					unit_type const& u,
+					unit_type const& v,
+					unit_type const& l
+					) const
+				{
+					return sprout::darkroom::coords::add(
+						c,
+						position_type(
+							sprout::darkroom::coords::z(c) * u / l,
+							v,
+							-sprout::darkroom::coords::x(c) * u / l
+							)
+						);
+				}
+				SPROUT_CONSTEXPR position_type transform(
+					position_type const& c,
+					unit_type const& u,
+					unit_type const& v
+					) const
+				{
+					using std::sqrt;
+					using std::sin;
+					using std::cos;
+					return transform_1(
+						c,
+						u * cos(rotate_) - v * sin(rotate_),
+						u * sin(rotate_) + v * cos(rotate_),
+						sqrt(
+							sprout::darkroom::coords::x(c) * sprout::darkroom::coords::x(c)
+								+ sprout::darkroom::coords::z(c) * sprout::darkroom::coords::z(c)
+							)
+						);
+				}
+				template<typename Unit2D>
+				SPROUT_CONSTEXPR position_type reference_width(
+					Unit2D const& x,
+					Unit2D const& y,
+					Unit2D const& width,
+					Unit2D const& height,
+					unit_type const& rate
+					) const
+				{
+					return transform(
+						sprout::darkroom::coords::resize(
+							sprout::darkroom::coords::sub(fixation_point_, position_),
+							far_plane_
+							),
+						static_cast<unit_type>(x) / width - 0.5,
+						-((static_cast<unit_type>(y) / height - 0.5) * rate)
+						);
+				}
+				template<typename Unit2D>
+				SPROUT_CONSTEXPR position_type reference_height(
+					Unit2D const& x,
+					Unit2D const& y,
+					Unit2D const& width,
+					Unit2D const& height,
+					unit_type const& rate
+					) const
+				{
+					return transform(
+						sprout::darkroom::coords::resize(
+							sprout::darkroom::coords::sub(fixation_point_, position_),
+							far_plane_
+							),
+						(static_cast<unit_type>(x) / width - 0.5) * rate,
+						-(static_cast<unit_type>(y) / height - 0.5)
+						);
+				}
 			public:
 				SPROUT_CONSTEXPR explicit basic_simple_camera(
-					unit_type const& far_plane
+					unit_type const& far_plane,
+					angle_of_view_reference::values reference_value = angle_of_view_reference::long_side,
+					position_type const& position = position_type(0, 0, -1),
+					position_type const& fixation_point = position_type(0, 0, 0),
+					unit_type const& rotate = 0
 					)
 					: far_plane_(far_plane)
+					, reference_value_(reference_value)
+					, position_(position)
+					, fixation_point_(fixation_point)
+					, rotate_(rotate)
 				{}
-				SPROUT_CONSTEXPR ray_type operator()(unit_type const& u, unit_type const& v) const {
+				template<typename Unit2D>
+				SPROUT_CONSTEXPR ray_type operator()(
+					Unit2D const& x,
+					Unit2D const& y,
+					Unit2D const& width,
+					Unit2D const& height
+					) const
+				{
 					return ray_type(
-						position_type(0, 0, 0),
-						sprout::darkroom::coords::normalize(position_type(u, v, far_plane_))
+						position_,
+						sprout::darkroom::coords::normalize(
+							(reference_value_ == angle_of_view_reference::long_side && width >= height)
+								|| (reference_value_ == angle_of_view_reference::short_side && width < height)
+								|| reference_value_ == angle_of_view_reference::width
+								? reference_width(x, y, width, height, static_cast<unit_type>(height) / width)
+								: reference_height(x, y, width, height, static_cast<unit_type>(width) / height)
+							)
 						);
 				}
 			};
@@ -34,8 +137,27 @@ namespace sprout {
 			//
 			template<typename Unit>
 			SPROUT_CONSTEXPR inline sprout::darkroom::cameras::basic_simple_camera<Unit>
-			make_simple_camera(Unit const& far_plane) {
-				return sprout::darkroom::cameras::basic_simple_camera<Unit>(far_plane);
+			make_simple_camera(
+				Unit const& far_plane,
+				typename sprout::darkroom::cameras::basic_simple_camera<Unit>::angle_of_view_reference::values reference_value
+					= sprout::darkroom::cameras::basic_simple_camera<Unit>::angle_of_view_reference::long_side
+					,
+				typename sprout::darkroom::cameras::basic_simple_camera<Unit>::position_type const& position
+					= typename sprout::darkroom::cameras::basic_simple_camera<Unit>::position_type(0, 0, -1)
+					,
+				typename sprout::darkroom::cameras::basic_simple_camera<Unit>::position_type const& fixation_point
+					= typename sprout::darkroom::cameras::basic_simple_camera<Unit>::position_type(0, 0, 0)
+					,
+				Unit const& rotate = 0
+				)
+			{
+				return sprout::darkroom::cameras::basic_simple_camera<Unit>(
+					far_plane,
+					reference_value,
+					position,
+					fixation_point,
+					rotate
+					);
 			}
 		}	// namespace cameras
 	}	// namespace darkroom
diff --git a/sprout/darkroom/coords/vector.hpp b/sprout/darkroom/coords/vector.hpp
index c01b2484..6f78be28 100644
--- a/sprout/darkroom/coords/vector.hpp
+++ b/sprout/darkroom/coords/vector.hpp
@@ -114,6 +114,23 @@ namespace sprout {
 					;
 			}
 			//
+			// cross
+			//
+			template<typename Vector1, typename Vector2>
+			SPROUT_CONSTEXPR inline Vector1 cross(Vector1 const& lhs, Vector2 const& rhs) {
+				return sprout::tuples::remake_clone<Vector1>(
+					lhs,
+					sprout::darkroom::coords::y(lhs) * sprout::darkroom::coords::z(rhs)
+						- sprout::darkroom::coords::z(lhs) * sprout::darkroom::coords::y(rhs)
+						,
+					sprout::darkroom::coords::y(lhs) * sprout::darkroom::coords::x(rhs)
+						- sprout::darkroom::coords::x(lhs) * sprout::darkroom::coords::y(rhs)
+						,
+					sprout::darkroom::coords::x(lhs) * sprout::darkroom::coords::y(rhs)
+						- sprout::darkroom::coords::y(lhs) * sprout::darkroom::coords::x(rhs)
+					);
+			}
+			//
 			// normalize
 			//
 			namespace detail {
@@ -139,6 +156,16 @@ namespace sprout {
 					);
 			}
 			//
+			// resize
+			//
+			template<typename Vector, typename Fac>
+			SPROUT_CONSTEXPR inline Vector resize(Vector const& lhs, Fac const& rhs) {
+				return sprout::darkroom::coords::detail::normalize_impl(
+					lhs,
+					sprout::darkroom::coords::length(lhs) / rhs
+					);
+			}
+			//
 			// reflect
 			//
 			template<typename Incident, typename Normal>
diff --git a/sprout/darkroom/tracers/raytracer.hpp b/sprout/darkroom/tracers/raytracer.hpp
index 1d2bd21d..7b92036d 100644
--- a/sprout/darkroom/tracers/raytracer.hpp
+++ b/sprout/darkroom/tracers/raytracer.hpp
@@ -21,17 +21,17 @@ namespace sprout {
 					typename Camera,
 					typename Objects,
 					typename Lights,
-					typename Unit
+					typename Unit2D
 				>
 				SPROUT_CONSTEXPR color_type operator()(
 					Renderer const& renderer,
 					Camera const& camera,
 					Objects const& objs,
 					Lights const& lights,
-					Unit const& x,
-					Unit const& y,
-					Unit const& width,
-					Unit const& height,
+					Unit2D const& x,
+					Unit2D const& y,
+					Unit2D const& width,
+					Unit2D const& height,
 					std::size_t depth_max = 8
 					) const
 				{
@@ -39,10 +39,7 @@ namespace sprout {
 						camera,
 						objs,
 						lights,
-						camera.template operator()(
-							static_cast<typename Camera::unit_type>(x) / width - 0.5,
-							-(static_cast<typename Camera::unit_type>(y) / height - 0.5)
-							),
+						camera.template operator()(x, y, width, height),
 						depth_max
 						);
 				}