Minimal-Cut Model Composition

T.Hassner, L.Zelnik-Manor, G.Leifman, and R.Basri


Best Student Paper Award


Constructing new, complex models is often done by re-using parts of existing models, typically by applying a sequence of segmentation, alignment and   composition operations. Segmentation, either manual or automatic, is rarely adequate for this task, since it is applied to each model independently, leaving it to the user to trim the models and determine where to connect them. In this paper we propose a new composition tool. Our tool obtains as input two models, aligned either manually or automatically, and a small set of constraints indicating which portions of the two models should be preserved in the final output. It then automatically negotiates the best location to connect the models, trimming and stitching them as required to produce a seamless result. We offer a method based on the graph theoretic minimal cut as a means of implementing this new tool. We describe a system intended for both expert and novice users, allowing easy and flexible control over the composition result. In addition, we show our method to be well suited for a variety of model processing applications such as model  repair, hole filling, and piecewise rigid deformations.

Full paper : SMI05_MinCutModelComposition.pdf (2,503kb). BibTeX.

Some Results

More results can be found in the paper.

The Centaur

A typical composition session. The stages involved in creating the centaur model from those of a man and horse. (I) Input. (II) Placement (semi-automatic, using our novel part-in-whole alignment method, or manual). (III) Constraint selection (manual). (IV)  transition volume selection (manual or taking the bounding box of the union as a default selection). (V) The recovered transition surface (automatic). (VI) Clipped models (automatic).
The man model, courtesy of Cyberware and Headus.

Centaur model

The final, stitched, centaur result.

Composing Heads

Composing heads

Reversing constraints. From left to right: The two busts; The models overlayed; First example, taking the blue face and red head; Second example, reversing constraints, now choosing the red face and blue head. In both, top is the cut result (clipped models) bottom is the final result.
Both bust models, courtesy of Cyberware



Multi-step composition. Cerberus, the mythical guardian of the gates of hell, is created here in four steps. The top row shows overlays of the models used to create the result in each step (shown in the bottom row). In step 1 we deform the dog's head, turning it to make room for the other heads. Additional heads were created by cloning and rotating the whole dog. In each step we constrained the new dog's head and the existing dog's torso and nose(s). The tail was added by composing the existing tail with a serpent model (in blue).

Model Restoration

Restoring the scars on the Igea artifact

Model restoration. Fixing the scars and broken nose on the Igea artifact model, in three steps. (a) Input model and the user drawn boxes around the flaws. (b) Overlay of the input model and the aligned database bust model chosen to fix each flaw. (c) Clipped models. (d) Input (left) and result (right).
The Igea artifact  model, courtesy of Cyberware.

Model Hole Filling

Model Hole Filling

Hole filling. Artificial holes opened in a bust model by removing both the nose and the top of the head. These were automatically repaired in two steps. In each row on the left is the input model  (with the user drawn box around the hole) and on the right is the final result (the little lump on the man's head is not an artifact. It is the tip of the cap worn by the scanned subjects in the database).
Bust models used for model restoration and holefilling are free samples from the CAESAR database.


Composing a chair

Composing a chair. From top to bottom, the three composition steps in creating a chair. On the left are the models overlayed; on the right are the composition results. Note that in each step, multiple models (e.g., the four legs, the six back rests) were treated as one model and composed in a single step with an additional model (e.g., the seat).

Final chair result

The final chair result.

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Faculty of Mathematics and Computer Science
Computer Vision Group

Last update:  Dec. 08, 2005
For questions and remarks please contact:  Tal Hassner.
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