Felt Tips posts a great tutorial series taking a look at Layer Space Transformations, and specifically, using expressions to control 3D spaces in After Effects. Aimed at the intermediate to advanced users who want to extend After Effects 3D capabilities with Expressions.

It’s essential to understand these coordinate systems, because the toWorld and fromWorld methods that I take a look at in a later part of this tutorial are used specifically to switch between world space and layer space

Felt Tips covers layer space transforms, the expression root, and where things are in space, and where they appear on the screen, and provides a great look at understanding layer space with After EFfects 3D layers and expressions with some great explanation and a few great examples.

Manipulating 3D Space with Expressions in After Effects – Introduction

Manipulating 3D Space with Expressions in After Effects – The Principle

Manipulating 3D Space with Expressions in After Effects – Visualizing Layer Spaces

Manipulating 3D Space with Expressions in After Effects – Auto Focus Example

Manipulating 3D Space with Expressions in After Effects – Example Showtime

Manipulating 3D Space with Expressions in After Effects – Example UFO