1. An encoded filament for use in an additive manufacturing system having an extrusion head, the encoded filament comprising: compositionally, a consumable material; a longitudinal length; volume-increment markings that are offset from each other along the longitudinal length of the encoded filament by increment lengths that vary to define segments of the encoded filament having volumes that are substantially the same, wherein the volume-increment markings are configured to be read by an optical sensor of the additive manufacturing system; and a cross-sectional geometry configured to be received by a liquefier of the extrusion head for building a three-dimensional model from the consumable material.