Value noise and Perlin noise are bother coherent noise functions based on integer lattices. Perlin noise is a type of gradient noise. Value noise defines a pse

Value noise and Perlin noise are bother coherent noise functions based on integer lattices. Perlin noise is a type of gradient noise. Value noise defines a pseudrandom value for each lattice point. Intermediate points are determined by interpolating the values of the adjacent lattice points. Value noise has discontinuous derivatives and looks blocky. Gradient noise defines a pseudo-randomly oriented vector at each lattice point. To find the value of an intermediate point you interpolate the vectors. If this stuff is interesting, I strongly recommend Texturing & Modeling: A Procedural Approach.