SOM U-Matrix generation

Question

I have been searching online and trying to understand the literature I have, but something is eluding me.

Given a SOM, when visualized with a U-Matrix, does the U-Matrix represent the distance between a given node and every other node, or the distance between a node and its direct neighbours?

Regards, Jack Hunt

EDIT:- Suggestions for alternative visualization techniques are welcome.

Answer 1

Generally the color of a node in the U-matrix is based on the distance between neighboring nodes in the lattice (link). There are other ways to color a U-matrix, but that is the most common.

Other visualization techniques depend entirely upon your data and what you are looking for.