Parallax mapping is an enhancement of the bump mapping

Bump mapping

Bump mapping is a technique in computer graphics for simulating bumps and wrinkles on the surface of an object. This is achieved by perturbing the surface normals of the object and using the perturbed normal during lighting calculations. The result is an apparently bumpy surface rather than a...

 or normal mapping

Normal mapping

In 3D computer graphics, normal mapping, or "Dot3 bump mapping", is a technique used for faking the lighting of bumps and dents. It is used to add details without using more polygons. A common use of this technique is to greatly enhance the appearance and details of a low polygon model by...

 techniques applied to textures in 3D rendering

Rendering (computer graphics)

Rendering is the process of generating an image from a model , by means of computer programs. A scene file contains objects in a strictly defined language or data structure; it would contain geometry, viewpoint, texture, lighting, and shading information as a description of the virtual scene...

 applications such as video games. To the end user, this means that textures

Texture mapping

Texture mapping is a method for adding detail, surface texture , or color to a computer-generated graphic or 3D model. Its application to 3D graphics was pioneered by Dr Edwin Catmull in his Ph.D. thesis of 1974.-Texture mapping:...

 such as stone walls will have more apparent depth and thus greater realism with less of an influence on the performance of the simulation. Parallax mapping was introduced by Tomomichi Kaneko et al. in 2001.

Parallax mapping is implemented by displacing the texture coordinates at a point on the rendered polygon

Polygon

In geometry a polygon is a flat shape consisting of straight lines that are joined to form a closed chain orcircuit.A polygon is traditionally a plane figure that is bounded by a closed path, composed of a finite sequence of straight line segments...

 by a function of the view angle in tangent space (the angle relative to the surface normal) and the value of the height map at that point. At steeper view-angles, the texture coordinates are displaced more, giving the illusion of depth due to parallax

Parallax

Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...

 effects as the view changes.

Parallax mapping described by Kaneko is a single step process that does not account for occlusion. Subsequent enhancements have been made to the algorithm incorporating iterative approaches to allow for occlusion and accurate silhouette rendering.

Steep parallax mapping

Steep parallax mapping is one name for the class of algorithms that trace rays against heightfields. The idea is to walk along a ray that has entered the heightfield's volume, finding the intersection point of the ray with the heightfield. This closest intersection is what part of the heightfield is truly visible. Relief mapping and parallax occlusion mapping

Parallax occlusion mapping

Parallax occlusion mapping is an enhancement of the parallax mapping technique. Parallax occlusion mapping is used to procedurally create 3D definition in textured surfaces, using a displacement map instead of through the generation of new geometry...

are other common names for these techniques.

Interval mapping improves on the usual binary search done in relief mapping by creating a line between known inside and outside points and choosing the next sample point by intersecting this line with a ray, rather than using the midpoint as in a traditional binary search.

External links

• Comparison from the Irrlicht Engine
  Irrlicht Engine
  Irrlicht is an open source 3D engine written in C++. It is cross-platform, officially running on Windows, Mac OS X, Linux and Windows CE and due to its open nature ports to other systems are available, including Xbox, PlayStation Portable, SymbianOS and iPhone.Irrlicht is known for its small size...
  
  : With Parallax mapping vs. Without Parallax mapping
• Parallax mapping implementation in DirectX, forum topic
• Parallax Mapped Bullet Holes - Details the algorithm used for F.E.A.R. style bullet holes.
• Interval Mapping
• Parallax Mapping with Offset Limiting
• Steep Parallax Mapping