How close is a quad mesh to a polycube?

We compute the shortest sequence of local connectivity modifications that transform a genus 0 quad mesh to a polycube. The modification operations are (dual) loop preserving and thus, we are restricted to quad meshes where loops don't self-intersect and two loops intersect at most twice. The intersection patterns of the loops are encoded in a simplicial complex, which we call loop complex. To formulate the modification search over the loop complex, we characterise polycubes combinatorially and determine dependencies between modifications. We show that the full task can be encoded as a mixed-integer problem that is solved by a commodity MIP-solver. We demonstrate the practical feasibility by a number of examples with varying complexity.