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Pointshop 3D An Interactive System for Point-based Surface Editing

Pointshop 3D An Interactive System for Point-based Surface Editing. Matthias Zwicker Mark Pauly Oliver Knoll Markus Gross. ETH Z ürich. Outline. Introduction Pointshop3D system components Point cloud parameterization Dynamic sampling Editing operators Demo Conclusions.

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Pointshop 3D An Interactive System for Point-based Surface Editing

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  1. Pointshop 3D An Interactive System for Point-based Surface Editing Matthias Zwicker Mark Pauly Oliver Knoll Markus Gross ETH Zürich

  2. Outline • Introduction • Pointshop3D system components • Point cloud parameterization • Dynamic sampling • Editing operators • Demo • Conclusions

  3. Pointshop 3D • texturing • sculpting • filtering directly modifies point samples Point-Based 3D Content Creation Acquisition Display • structured light • laser scanning • etc. • surface splatting • Qsplat • etc. produces cloud of point samples uses points as rendering primitive

  4. Pixel: • color • alpha • ... 3D Surface 2D Image Pointshop 3D • Generalizes 2D photo editing concepts and functionality to 3D point-sampled surfaces • Surfel: • pixel + • position • normal • radius • Geometry editing: modify 3D positions and normals, e.g. sculpting and filtering

  5. Editing Operation

  6. Parameterization v u Editing Operation

  7. Reconstruction Editing Operation Parameterization v u

  8. Sampling Editing Operation Parameterization v u Reconstruction

  9. Resampling Operator Editing Operation Parameterization v u

  10. Resampling Operator Editing Operator Editing Operation Parameterization v u

  11. Resampling Operator Editing Operator Parameterization Editing Operation v u

  12. brush original surface modified surface Key Components • Point cloud parameterization • Dynamic resampling • Editing operator

  13. brush plane surface point parameter value Point Cloud Parameterization • Brush interaction • Parameterize by orthogonal projection 1 0

  14. Constraints Minimum Distortion Point Cloud Parameterization • Selection interaction • Constrained minimum distortion parameterization

  15. fitting constraints distortion surface points brush points Point Cloud Parameterization • Minimize objective function

  16. Point Cloud Parameterization • Measuring distortion • Integrates squared curvature using local polar re-parameterization

  17. discrete curvature k-neighborhood Point Cloud Parameterization • Discrete formulation: • Approximate second derivative with divided differences • Discretize integral using normal sections based on k-nearest neighbors

  18. Point Cloud Parameterization • Discrete formulation: • Leads to a linear least squares system • Efficiently solved using multi-grid approach

  19. fitting functions weight functions normalization factor Reconstruction • Parameterized scattered data approximation • Compute local fitting functions using local parameterization • Map to global parameterization using global parameter coordinates of neighboring points

  20. Reconstruction reconstruction with linear fitting functions Gaussian weight functions in parameter space

  21. Sampling • Three sampling strategies: • Sample at the original surface points • Sample at the brush points • Adaptive sampling, i.e. sample at surface or brush points depending on the local sampling density • Antialiasing • Band-limit the weight functions (Gaussians) before sampling using Gaussian low-pass filter  Surface splatting framework

  22. Editing Operators • Painting • Texture, material properties, transparency

  23. carving on a rough surface brush Editing Operators • 3D Sculpting brush normal displacement

  24. Editing Operators • Filtering geometry smoothing filter artistic texture filter

  25. Demo

  26. Discussion • Efficient point-based surface resampling • Robust reconstruction based on k-nearest neighbors requires: • No outliers • Sufficiently high, roughly uniform sampling density • Little noise • Geometry editing is restricted to displacements

  27. Ongoing & Future Work • Model cleaning • User-guided  provide appropriate tools • Automatic pre-process • More general modeling functionality • Free-form deformation • Physics-based modeling • Texture synthesis and transfer

  28. Conclusion • Pointshop3D provides sophisticated editing operations on point-sampled surfaces • points are a versatile and powerful graphics primitive • Software release in fall 2002 on www.pointshop3d.com

  29. Acknowledgements • Tim Weyrich • Martin Roth • CGL, ETH Zürich • European Graduate Program on Combinatorics, Geometry and Computation • MERL

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