1. A dimensioning system, comprising: an illumination subsystem operable for successively emitting sequences of spatial patterns of illumination toward a target object, each of the sequences comprising an initial spatial illumination pattern and a refined spatial illumination pattern subsequent to the initial spatial illumination pattern, wherein the refined spatial illumination pattern is spatially different than the initial spatial illumination pattern; a sensor positioned for detecting illumination returning from the target object; and a control subsystem communicatively coupled to the sensor and the illumination subsystem, wherein the control subsystem is operable for: determining an approximate boundary of a portion of the target object based on the detected illumination; determining a refined spatial illumination pattern based on the determined approximate boundary; causing the illumination subsystem to emit the determined refined spatial illumination pattern; and determining an approximate volume of the target object based on illumination returned from the target object when illuminated by the refined spatial illumination pattern.