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Sketch Beautification: Progress and Plans

Sketch Beautification: Progress and Plans. 2005-09-05 Weekly Seminar Kaisuke Nakajima. Motivation. It’s hard to draw diagrams on computers for documents, slides,. Goal. Facilitate diagram drawing As easy as (or easier than) sketching. Previous work. Many systems with sketching interface

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Sketch Beautification: Progress and Plans

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  1. Sketch Beautification: Progress and Plans 2005-09-05 Weekly Seminar Kaisuke Nakajima

  2. Motivation It’s hard to draw diagrams on computers • for documents, slides, ...

  3. Goal Facilitate diagram drawing • As easy as (or easier than) sketching

  4. Previous work • Many systems with sketching interface • But: not mature enough for practical use • Limited types of shapes • Problems with ambiguity

  5. Limited types of shapes (1/2) Lines, circles, arcs [Igarashi et al. 1997] [Arvo and Novins 2000] [Unpublished; Rejected for Eurographics 2005]

  6. ellipse Limited types of shapes (2/2) But: supporting more shapes is not so easy • If we add support for ellipses... • How can we draw a perfect circle by sketch? circle An ellipse never fits worse than a circle...

  7. Problems with ambiguity • No support for error correction • Too many recognition candidates Be identical!  [Pavlidis and Van Wyk 1985] Too many candidates shown in a small area!  [Igarashi et al. 1997]

  8. Focus • Support richer set of shapes • Circles, arcs, ellipses, and Bézier curves • Better handling of ambiguity • By a better recognition algorithm & UI

  9. Rest of today’s talk • Current implementation • Plans

  10. Current Implementation

  11. Status • We can beautify a (very) simple diagram

  12. Algorithm overview 1. Fit primitive shapes to strokes 2. Infer geometric constraints 3. Solve obtained constraints

  13. 1. Fit primitive shapes • For each stroke • Fit each shape  Choose the best shape • Supported shapes • Only lines & circles for now...

  14. 2. Infer constraints • Example: • Others: • length[i] = length[j] • angle[i] = angle[j] • distance(point[i], point[j]) = length[k] for all (point1, point2) if (distance(point1, point2) < 32) add constraint(point1 == point2);

  15. 3. Solve constraints External constraint solver: Chorus [Hosobe 2001] ChSolver s = new ChSolver(); ChVariable2D p1, p2; ChVariable d; ... s.add(new ChEuclideanConstraint(p1, p2, d)); s.solve(); //  distance(p1, p2) == d

  16. Flaws • Too rough & ad-hoc • Too few types of shapes & constraints • Irresponsible thresholds • Unstable & slow • Redundant (or unsolvable) set of constraints if (distance(point1, point2) < 32) add constraint(point1 == point2); add constraint(point1.x == 10); ... add constraint(point1.x == 20);

  17. Plans

  18. Plans • Handling constraints • Handling ambiguity • Adding more shapes • Extensions

  19. apply constraint #1: ignore constraint #2: Handling constraints (1/3) add constraint(point1.x == 10); ... add constraint(point1.x == 20); • Select a proper subset of constraints • When we have N possible constraints: • There are candidates

  20. Handling constraints (2/3) • Less candidates actually • To bind V variables, V constraints are enough • e.g. If P points are to be beautified, V = 2P • candidates • V = 4 in Pegasus [Igarashi et al. 1997] • V ≫ 4 occurs in our approach  Impossible to try them all

  21. apply constraint #1: ignore Bad! Good! constraint #2: Handling constraints (3/3) • Pick up only the better few candidates • cf. game tree search • Evaluate candidates & prune bad branches • Evaluation factor: error from original stroke, beauty

  22. Handling ambiguity (1/3) • 100% accurate recognition is impossible • Worst way: ignore errors! • Better way: choose from candidates • Still bad if too many candidates

  23. Handling ambiguity (2/3) • cf. Japanese IME (input method) 78 kanji’s in no specific order!  Much user friendly 

  24. Handling ambiguity (3/3) • Analogy: Let the use redraw • The system can reduce candidates Ambiguity (Noise/Signal ratio) decreases by redrawing.

  25. circle ellipse Adding more shapes • Redrawing can handle the ellipse-or-circle problem • Which candidate should come first?  Determine based on user profile (logging)

  26. Extensions • Coloring • Embedding in text • Designing fonts

  27. Extensions: Coloring • Coloring of vector graphics can be difficult • e.g. Adobe Illustrator requires complicated path editing commands

  28. v u angle Extensions: Embedding (Takeo’s idea.) • Embed diagrams in a text file • Not a separate file Pop up!

  29. Extensions: Designing fonts • Fonts: good target for testing • Difficult to design & modify • Partial similarity (curves, serifs, ...)

  30. Schedule • Job priority (from high to low) • Improve candidate search • Implement user redrawing • Add more shapes / constraints • Extensions • Quite urgent... • WISS 2005 Demo (Due 9/23)

  31. Summary • I want to facilitate diagram-drawing • Previous systems not mature for practical use • Implemented a rudimental prototype • Much improvements to be done Thanks!

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