What is relief mapping?

In computer graphics, especially three -dimensional (3D) computer graphics, the relief mapping is a way to apply a two -dimensional (2D) image to the surface of the object to modify the appearance of its geometry. The embossed map is a 2D image in which each image determines the height of the corresponding location on the 3D model or is alternately transparent to indicate that there is no geometry at a given point in the model. When the 2D image is mapped to the surface of the 3D object, the drawing motor adjusts the geometry of the object and moves each point associated with the pixel in the 2D image at a certain distance from the original coordinates that corresponds to its texture pixel. This allows a very fine amount of detail that can respond to light, throw precise shadows and even cover the objects in the background without the need for fine, memory networks to create geometry. One examples of this type of mapping could be the use of satellite photography of the country into a ball, with a relief mapping causing the points on the surface of the ball are higherM where the mountains are and remain flat where the oceans are.

Relief mapping relies on 2D image texture for data necessary to render the object. The 2D image consists of pixels of different colors and each color is converted to a specific height. Most of these images are in the gray stage, because it is easy to determine the height of the area where black will be equal to any height, clean white will be the maximum height and gray will form the values ​​between.

When an object has a 2D texture applied to relief mapping, the location of each pixel is assigned to a point in the geometry of the object. If the texture pixel in the figure called Texel, a different value other than zero, then the 3D coordinates of the model surface is adjusted by the pixel value of the object the object in the surface direction normal. The amount of movement that each texel unit represents can be set very low, so the relief mapping can only be used to make fine deformities on the surfaceChu, or can be set high, so the relief texture map is converted to a wild terrain.

In computer graphics, there are many uses for relief mapping, from the display of 2D cartographic maps in 3D to geometric simulation of very detailed textures, such as a woven surface of the sweater. It should be noted that relief mapping is very similar to the bump mapping and some programs actually optimize remote mapping in the scene by returning to the mapping. The main difference is that although some similar surface effects can be achieved, impact mapping never causes that the geometry of the object stands out outside its basic geometric shape. This means that if the ball is mapped with the image of the mountains, then the visible surface will be precisely designed by the mountains, but the edges of the balls and the shadow of the ball will remain perfectly round. The technique of relief mapping would actually modify the ball so that its geometry reflects the height of the texture.