Displacement Mapping

View -dependent displacement mapping (VDM ) refers to a technique in computer graphics that is used to give a surface of a three-dimensional object greater detail and thus achieve a more realistic representation.

Basics

3D objects in computer graphics consist initially of a grid or polygons on the later so-called texture ( for example, the image of a wall) is placed. One can get the texturing, so imagine attaching a texture as if its surface would be glued to the wireframe model of an object to be displayed. Apart from the actual texture data usually contain the final color development of the surface, other types of texture data ( for example, the surface characteristics described ) referred to as "texture" occasionally.

Application

A so-called height -map ( eng. for height map, relief) generated - Together with the actual texture of the object is - mostly from this. This is an image that can be used in the most grayscale to indicate height information. Of these, a cross section through the surface to be created, and thus a relief can be so produced.

The points of the grid ( vertices ) are moved according to these texture information along its normal, i.e. perpendicular to the surface. For example, it is possible to transfer an elevation relief by applying a displacement map on a flat (planar ) surface and thus provide it with a rough texture. In addition to its displacement refinement may be needed depending on the density of the wire mesh. This is called tessellation ( tiling, en: tessellation ).

Example

In the example of a wall by means of displacement mapping a surface is to be awarded, projecting on each individual brick in relation to the joint a little. As a template we used a corresponding texture ( Figure 1). This is used to create the Height map (Figure 2).

Advantages over other methods

In contrast to the normal mapping and bump mapping which has the displacement mapping has the advantage that the geometry of the object is actually modified. That is, we consider a surface up close at a shallow angle, so its structure is still visible. In contrast, the surfaces appear absolutely planar by other methods, as soon as one " side " considered, thereby also go the effects that simulate by mere color changes a structure lost. Under the influence of light sources and shadows interact with the displacement mapping, realistic structures created since the change in geometry also affects the lighting ( for example, when a shadow viewed from a low angle surface).