SDF / Signed Distance Function/Field

A signed distance function (SDF) is a mathematical function that describes the distance from a point in space to the surface of an object. The function returns a positive value if the point is outside the object, a negative value if the point is inside the object, and zero if the point is on the surface of the object.

the terms field and function are often used interchangeably, but the term field can also refer to pre-computed grid of distances as in the case of Valve’s font rendering technique.

Usage in Computer Graphics

SDFs when combine to ray marching can be used to render complex shapes and scenes in real-time. They are particularly useful for rendering fractals, organic shapes, smooth surfaces, and other geometrically complex objects that are difficult to represent with traditional polygonal meshes.

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