  We present an efficient, trivially parallelizable algorithm to compute offset
surfaces of shapes discretized using a dexel data structure. Our algorithm is
based on a two-stage sweeping procedure that is simple to implement and
efficient, entirely avoiding volumetric distance field computations typical of
existing methods. Our construction is based on properties of half-space power
diagrams, where each seed is only visible by a half-space, which were never
used before for the computation of surface offsets. The primary application of
our method is interactive modeling for digital fabrication. Our technique
enables a user to interactively process high-resolution models. It is also
useful in a plethora of other geometry processing tasks requiring fast,
approximate offsets, such as topology optimization, collision detection, and
skeleton extraction. We present experimental timings, comparisons with previous
approaches, and provide a reference implementation in the supplemental
material.
