spacedomain

Spacedomain is a term used in various disciplines to denote the spatial portion of a problem’s domain—the set of spatial coordinates over which a function is defined. In many contexts it is used synonymously with "spatial domain" and is often contrasted with other domains such as the time domain or the frequency domain. The exact usage can vary by field, and some authors prefer the two-word form "spatial domain."

In mathematics and physics, if a function u is defined on a region Ω ⊂ R^n, Ω is called its spatial domain. Problems such as the Poisson equation, the heat equation, and other boundary-value problems are posed on Ω with boundary conditions on ∂Ω. The geometry and topology of the spatial domain influence the behavior of solutions and the methods used for numerical discretization, such as finite element or finite difference schemes.

In signal processing and imaging, the spatial domain refers to operations that act directly on spatial coordinates of data, for example pixel values in an image. Spatial-domain filtering (smoothing, sharpening) contrasts with frequency-domain methods that operate after a transform such as the Fourier transform. In imaging, many features are analyzed and modified in the spatial domain by examining local neighborhoods around each point.

Other uses include geography and GIS, where the spatial domain describes the geographic extent of data, and machine learning, where the term may refer to the input feature space or the domain over which a model operates. Spacedomain is thus a versatile label that is most often linked to the concept of space as the domain of definition for a function or data. See also spatial domain, domain, time domain, and frequency domain.