Slippage-Preserving Reshaping of Human-Made 3D Content

Chrystiano Araújo
Nicholas Vining
Silver Burla
Manuel Ruivo de Oliveira
Enrique Rosales
Alla Sheffer

- University of British Columbia, Canada
- University of British Columbia, Canada and NVIDIA, Canada
- University of British Columbia, Canada
- University of British Columbia, Canada
- University of British Columbia, Canada
- University of British Columbia, Canada

ACM Transactions on Graphics (SIGGRAPH Asia), 2023

Comparisons against an output manually created by a professional artist, state-of-the-art 3D defomation methods (As-Rigid-As-Possible [Chao et al. 2010] and Conformal [Vaxman et al. 2015]), baseline Poisson deformation, and our 3D extension of 2D ALUP reshaping.

Artists often need to reshape 3D models of human-made objects by changing the relative proportions or scales of different model parts or elements while preserving the look and structure of the inputs. Manually reshaping inputs to satisfy these criteria is highly time-consuming; the edit in our teaser took an artist 5 hours to complete. However, existing methods for 3D shape editing are largely designed for other tasks and produce undesirable outputs when repurposed for reshaping. Prior work on 2D curve network reshaping suggests that in 2D settings the user-expected outcome is achieved when the reshaping edit keeps the orientations of the different model elements and when these elements scale as-locally-uniformly-as-possible (ALUP). However, our observations suggest that in 3D viewers are tolerant of non-uniform tangential scaling if and when this scaling preserves slippage and reduces changes in element size, or scale, relative to the input. Slippage preservation requires surfaces which are locally slippable with respect to a given rigid motion to retain this property post-reshaping (a motion is slippable if when applied to the surface, it slides the surface along itself without gaps). We build on these observations by first extending the 2D ALUP framework to 3D and then modifying it to allow non-uniform scaling while promoting slippage and scale preservation. Our 3D ALUP extension produces reshaped outputs better aligned with viewer expectations than prior alternatives; our slippage-aware method further improves the outcome producing results on par with manual reshaping ones. Our method does not require any user input beyond specifying control handles and their target locations. We validate our method by applying it to over one hundred diverse inputs and by comparing our results to those generated by alternative approaches and manually. Comparative study participants preferred our outputs over the best performing traditional deformation method by a 65% margin and over our 3D ALUP extension by a 61% margin; they judged our outputs as at least on par with manually produced ones.

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Comparisons with ARAP [Chao et al. 2010].

Comparisons with Conformal deformation [Vaxman et al. 2015].

Comparisons with baseline Poisson deformation.

Comparisons against our 3D extension of 2D ALUP reshaping [Araújo et al. 2022].

Additional comparisons with prior methods.

Note: some of the input models shown are copyrighted by third parties and used with their permission. See the paper for details.

@article{araujo23reshaping,
      author    = {Ara\'{u}jo, Chrystiano and Vining, Nicholas and Burla, Silver and Ruivo de Oliveira, Manuel
                   and Rosales, Enrique and Sheffer, Alla},
      title     = {Slippage-Preserving Reshaping of Human-Made 3D Content},
      journal   = {ACM Transaction on Graphics},
      year      = {2023},
      volume    = {42},
      number    = {6},
      doi       = {https://doi.org/10.1145/3618391},
      publisher = {ACM},
      address   = {New York, NY, USA}
    }