The Physical Model of Digital Elevation

Digital screens are physically flat, two-dimensional surfaces. Yet, users interact with interfaces as though they possess physical depth: dialogs float above pages, dropdowns hover over tables, and buttons depress when clicked.

We create this illusion of three-dimensional depth using Elevation:

• In the physical world, an overhead light source casts shadows based on how close an object is to the surface.
• An object resting flat on a desk casts a tight, sharp, dark shadow.
• As the object rises higher into the air (closer to the light source), its shadow becomes larger, softer, more blurred, and lower in contrast.

Understanding this physical relationship allows design systems to establish realistic, harmonious elevation tokens.