Texel Density measurement unit

Texel density (also referred to as pixel density or texture density) is a measurement unit used to make asset textures cohesive compared to each other throughout your entire world.

It’s measured in pixels per centimeter (ie: 2.56px/cm) or pixels per meter (ie: 256px/m).

https://www.beyondextent.com/deep-dives/deepdive-texeldensity