Editing Ray tracing (graphics) (section)

===SDF ray marching algorithm===

{{main|Ray marching#Distance-aided ray marching}}

In SDF ray marching, or sphere tracing,<ref>{{Citation
  | last1 = Hart | first1 = John C.
  | title = Sphere Tracing: A Geometric Method for the Antialiased Ray Tracing of Implicit Surfaces
  | journal = The Visual Computer
  | date = June 1995
  | url = http://graphics.stanford.edu/courses/cs348b-20-spring-content/uploads/hart.pdf}}</ref> each ray is traced in multiple steps to approximate an intersection point between the ray and a surface defined by a [[signed distance function]] (SDF). The SDF is evaluated for each iteration in order to be able take as large steps as possible without missing any part of the surface. A threshold is used to cancel further iteration when a point is reached that is close enough to the surface. This method is often used for 3-D fractal rendering.<ref>{{Citation
  | last1 = Hart | first1 = John C.
  | last2 = Sandin | first2 = Daniel J.
  | last3 = Kauffman | first3 = Louis H.
  | title = Ray Tracing Deterministic 3-D Fractals
  | journal = Computer Graphics
  | date = July 1989
  | volume = 23
 | issue = 3
 | pages = 289–296
 | doi = 10.1145/74334.74363
 | url = http://graphics.stanford.edu/courses/cs348b-20-spring-content/uploads/hart.pdf}}</ref>