U3M Fabric Files Explained
What a U3M digital material file contains, how it's captured, and how it's used to drive accurate cloth simulation.
What a U3M file contains
A U3M file bundles two kinds of data captured from a physical fabric sample: visual texture maps used for physically based rendering (color, normal, roughness, and displacement) and mechanical measurements — bending stiffness, stretch behavior, weight, and thickness — captured by a fabric scanning device.
How the data is captured
Fabric scanning hardware measures a physical swatch's response to bending and stretching forces along its warp, weft, and bias directions, alongside high-resolution imaging for the texture maps. The result is a file describing how that exact fabric behaves, not a generic approximation of 'cotton' or 'polyester'.
Using a U3M file in simulation
Importing a U3M file into Niche Studio's fabric library maps its mechanical parameters onto the XPBD simulation's stiffness and weight inputs, so a scanned fabric drapes and stretches in simulation the way the physical sample would on a mannequin — closing much of the gap between a digital render and a physical sample's fit.