Reflection mapping

Environment mapping, or reflection mapping is an efficient method to simulate the ( 3D ) computer graphics reflective surfaces and render. The surroundings of the reflecting object is stored as a texture, and imaged onto the surface of the object ( mapping). The most commonly used species in order to save the surrounding texture, are the spherical and cubic environment mapping. In the former, the texture, which is the environment shown on the interior of a ball, while in the vicinity zweiterem is " folded " on the six sides of a cube. The advantage of environment mapping with respect to ray tracing is the simpler and thus faster computation of the simulated reflections. The major disadvantage of this technique is that the environment must be known to be mirrored before the rendering of the object and thus to changing environments or self- reflections are not easy to implement.

Environment Mapping can also be used to illustrate transparent with a refractive index volume.

Spherical Environment Mapping

When spherical environment mapping ( in part as a standard environment mapping called ) the environment is mapped to the interior of a hollow sphere. The inner surface of the ball is projected on a 2D texture. Spherical textures are created with the help of a (virtual) fish -eye lens or by antecedent rendering of an existing virtual scene. The reflections, and the color of each pixel on the object can be determined by calculating the point on which the texture of the reflection vector points. Compared to ray tracing this operation is much faster to compute, since the imaged texture and thus all colors used are already in place. Since the ball is made of curved surfaces which can be projected (stretched ) on a straight 2D image distortion may arise which act ugly from certain angles from the edge of the texture. To overcome this circumstance, the cubic environment mapping has been developed.

Cubic environment mapping

Cubic environment mapping works basically the same as the spherical environment mapping, except that the environment is mapped to a cube (similar to a skybox ). Because the environment as straight surfaces can be projected, there are no distortions.