Bipul Mohanto

Bipul Mohanto

Doctoral Researcher@ Foveated Rendering | 3D Graphics Rendering| Global Illumination | Multi-View Rendering | Applied Human Perception | Color Science | Computer Vision

Volume Rendering

1 minute read

Published:

(work in progress…)

A popular volume rendering software, 3D Slicer directly named volume rendering as volume ray casting.

Volumetric Ray Casting

Isosurface Ray Casting

Ray Marching

Ray Marching is related to the volume rendering where rays interact with different scene particles. According to the Ray Tracing Gems, “the alternative of ray marching is the volume collision simulation”.

Ray marching (similiar to traditional ray tracing) is used for complex surface function. Ray tracing looks for the ray-object interaction only one way, while the ray marching can move forward and backward until it finds the intersection.

Sphere Tracing

Sphere tracing[1] is a variation of Ray Marching. However, according to Ray Tracing Gems, Sphere Casting could be more appropriate term. It is also sometimes referred to as SDF raymarching. Unlike the predetermined step size, sphere tracing relies on the Signed Distance Field (SDF) to determine safe advance along the ray so it does not hit anything. That makes the convergence much faster.

SDF (Signed Distance Function)

The SDF is also referred to as Signed Distance Field.

[2]

Resources

  1. John C. Hart, Sphere tracing: a geometric method for antialiased ray tracing of implicit surfaces (1996); url: https://graphics.stanford.edu/courses/cs348b-20-spring-content/uploads/hart.pdf
  2. https://iquilezles.org/articles/normalsSDF/

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