Isosurface

An isosurface is a three-dimensional analog of an isoline. It is a surface that represents points of a constant value (e.g. pressure, temperature, velocity, density) within a volume of space; in other words, it is a level set of a continuous function whose domain is 3-space.

The term isoline is also sometimes used for domains of more than 3 dimensions.[1]

Isosurface of vorticity trailed from a propeller blade. Note that this is an isosurface plotted with a colormapped slice.
  1. ^ "Hamilton–Jacobi equation", Wikipedia, 2020-12-06, retrieved 2020-12-14