Context-based Surface Completion


   Andrei Sharf     Marc Alexa     Daniel Cohen-Or


Completing a hole in a point-based model. In the darker colored region we removed sample points to demonstrate the surface completion technique. In the middle right the region is filled with a smooth patch conforming with the densely sampled areas, and the result of our context-based surface completion is on the right.





Sampling complex, real-world geometry with range scanning devices almost always yields imperfect surface samplings. These “holes” in the surface are commonly filled with a smooth patch that conforms with the boundary. We introduce a context-based method: the characteristics of the given surface are analyzed, and the hole is iteratively filled by copying patches from valid regions of the given surface. In particular, the method needs to determine best matching patches, and then, fit imported patches by aligning them with the surrounding surface. The completion process works top down, where details refine intermediate coarser approximations. To align an imported patch with the existing surface, we apply a rigid transformation followed by an iterative closest point procedure with non-rigid transformations. The surface is essentially treated as a point set, and local implicit approximations aid in measuring the similarity between two point set patches. We demonstrate the method at several point-sampled surfaces, where the holes either result from imperfect sampling during range scanning or manual removal.

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The reconstruction of a hole introduced in David's hair is applied top down, coarse to fine, where a large under-sampled area in the hair is first reconstructed at large coarse scales, and then refined through the levels of the hierarchy.




The back area of the sculpture “Youth” by Michelangelo as reconstructed from the original scans (left). Smooth filling in the middle and context-based completion of the point-sampled surface in the right.



A broken knot is repaired. This example shows that the filling technique is not sensitive to the topology. As long the initial algebraic surface approximation covers the missing part, the subsequent levels refine and reconstruct the finer details.




Completion of a missing region in a scan of a human bone. Our method completes successfully the ridge in the surface from its context.