Freeform surfaces are popular in architectural design for their expressive aesthetics, yet they remain challenging to fabricate. A common strategy is to approximate them with assemblies of planar polygonal panels in a process we term panelization, enabling cost-effective fabrication from sheet materials such as wood, metal, or glass. Our goal is to compute panelizations that are both geometrically faithful and structurally robust. A two-stage pipeline, i.e. geometric panelization followed by structural optimization, can be effective, but joint optimization may yield better outcomes by letting mechanics influence the panelization itself. The challenges are that the panelization task is inherently combinatorial, and structural objectives depend on stresses that have a complex, global dependence on the geometry and are costly to evaluate. Moreover, improving structural performance must be balanced against preserving the input surface's design intent. To address these challenges, we formulate panelization as a continuous surface flow coupled to stress analysis, by modeling candidates as creased elastic shells. We define a global objective by integrating an arbitrary function of stress over the shell and derive efficient gradients with respect to the surface shape to enable optimization. We further introduce flow terms that better preserve the input shape and show that running BFGS in a Sobolev space substantially outperforms standard BFGS and Sobolev gradient descent. We evaluate our method on architectural models, showing that incorporating stress during panelization yields substantial stress reductions and more robust designs compared to optimizing stress after fixing the panelization.

We introduce a high-performance framework for solving nonconvex optimization problems arising in simulation and geometry processing applications. Our framework especially benefits high-dimensional problems whose unknowns are spatial coordinates in ℝ d and whose objectives are expressed as a sum of element energies over small stencils. The Hessians of these problems have a block-sparse structure, where the nonzero entries are grouped into dense d × d blocks. Many works have exploited this structure to speed up the Hessian-vector products and nodal smoothers of iterative solvers. In contrast, accelerating direct sparse linear solvers, preferred for applications requiring high accuracy on unstructured grids, has been less explored. Our framework leverages block structure to accelerate all phases of a Newton-type minimization algorithm, from sparsity pattern construction to system assembly, matrix factorization, and solves. A fundamental piece of the framework is BlockCatamari, our highly tuned, block-accelerated multifrontal sparse Cholesky code that achieves significantly faster factorizations than existing direct solvers on shared-memory systems. We combine this solver with our fast parallel Hessian assembly routine, heuristics for conditionally enabling per-element Hessian projections, and strategies for minimizing symbolic factorization re-computations. We show that this leads to dramatic speedups on a large suite of benchmark problems involving injective surface parametrization and elasticity simulation with contact, and we further demonstrate the ease with which new energies can be defined at the different levels of abstraction offered by our framework.