Consider adding matcap shader

[delaneyj]

Demo

When setting a darker color I noticed that there are yellowish lights in the scene that can't be controlled. An alternative/addition to scene lighting that looks great is spherical light mapping. Here's a tutorial on implementing and a working three.js npm of the shader. Maybe the app checks for a certain property on the feature. It would enhance the visualization and in most cases in a forward pass faster than even a single point light in the scene (texture lookup vs many dot products).