Fundamental Noise Concepts A noise function is a real-valued function that takes on values between 0. and 1. over some domain.1 A noise function is often generated by determining pseudorandom numbers (PRNs) at each of a number of fixed points in a domain and processing those values to generate a function across the entire domain. If the domain is an interval, we have one-dimensional noise; if the domain is a plane region, we have two-dimensional noise; if the domain is a region in three-dimensional space, we have three-dimensional noise. The values of the noise function can be used to modify values of such things as the pixel properties in a fragment shader. In this section we will briefly introduce some kinds of noise functions and their properties, based on one-dimensional noise operations for simplicity.