Parallax mapping (also called offset mapping or virtual displacement mapping) is an enhancement of the
bump mapping or
normal mapping techniques applied to textures in 3D
rendering applications such as
video game
Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device to gener ...
s. To the end user, this means that
textures 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.
[Kaneko, T., et al., 2001]
Detailed Shape Representation with Parallax Mapping
In Proceedings of ICAT 2001, pp. 205-208.
Parallax mapping is implemented by displacing the texture coordinates at a point on the rendered
polygon
In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed '' polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the two t ...
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 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. Due to foreshortening, nearby object ...
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.
[Tatarchuk, N., 2005]
Practical Dynamic Parallax Occlusion Mapping
Siggraph presentations
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 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.
See also
*
Parallax scrolling
Parallax scrolling is a technique in computer graphics where background images move past the camera more slowly than foreground images, creating an illusion of depth in a 2D scene of distance. The technique grew out of the multiplane camera tec ...
References
External links
* Comparison from the
Irrlicht EngineWith Parallax mappingvs
Without Parallax mappingParallax mapping implementation in DirectX, forum topicParallax Mapped Bullet Holes- Details the algorithm used for F.E.A.R. style bullet holes.
{{Texture mapping techniques
Texture mapping