Bumpmapping

Bump mapping is a technique that takes 3D visualization programs are used to improve the level of detail of objects, without increasing the complexity of the geometry. The trick is that the required information is stored in a texture with the help of shades are drawn on a surface.

Bump mapping is thus only one ( albeit effective ) illusion, which simulates surface irregularities that are not present in the geometry of the model.

It improves the image quality and the degree of realism without significantly knock down on the time required for the rendering time. Additionally, the application field is not limited to shading. Reflections can be handled with this technique as well. Bump mapping is already playing a major role in the entertainment industry projects, since the visual quality can be significantly improved without affecting the performance, but worth mentioning.

Prerequisite for the use of bump maps is a lighting model that is based on per- pixel lighting. APIs such as DirectX or OpenGL already have all of the necessary routines. Usually, however, a combination of vertex and pixel shaders is used to control the necessary effects accurately.

The procedure was developed in 1978 by James F. Blinn.

Height - mapping

The relative height information are in a texture in the form of gray levels - the so-called heightmap. Each gray level represents a certain height. Normally black (level 0) is the " deepest " point and white ( value: 255), the " highest". This form of data storage is not limited to just bump mapping, more often it comes in the generation of large terrains for use.

Since differences in height be fooled by only varying shades of gray on the texture, but the surfaces remain smooth, step on some visible errors:

• When held flat, the structure is highly distorted.
• The silhouette remains as flat as the original object.
• It is thrown a smooth shadow.
• Bumps throw each other no shadows.

Application

The 3D modeller is based on two versions of a model: a high-resolution, highly detailed ( 100,000 polygons) and a certain for the finished program, undetaillierte ( 100-10,000 polygons). A program calculates the difference between the two models and describes the data obtained with a texture. This texture is then clamped to the low poly model. In the finished game / diagram / application the user gets the impression that the highly detailed model is used.

For simple shapes ( cracks, highlighted text ) and details that also appear in a hand-drawn color texture ( exfoliated paint, quirks, rivets ) is often created a bump map by hand by lifted the desired areas with light and dark shapes and lines or deepened, or the color texture is processed and converted into gray scale, that the desired effect is achieved.