1. Paper Bibliography
- Title: Sketch Based Interfaces: Early Processing for Sketch Understanding
- Authors: Tevfik Metin Sezgin, Thomas Stahovich, and Randall Davis
- Publication: ACM SIGGRAPH 2006 Courses. ACM, 2006.
2. Summary
- Target: free sketching
- Target Domain: mechanical engineering design
- Purpose: flexibility & easy to use
- Goal:
- Converting the original digitized pen strokes in a sketch into the intended geometric objects
- Combining multiple sources of knowledge
3. Definitions
- A single stroke: from mouse-down to mouse up
4. Details
- Free sketching
- The timing of pen motion can be very informative in regard to free sketching.
- There is no fixed shape to be recognized.
1. Stroke approximation
: approximate a stroke with more compact and abstract description while minimizing error and avoid overfitting
- Vertex detection
- Corner of a stroke = high local curvature
- Combining stroke direction, curvature and speed data
ex) corner: minimal of speed or maxima of the absolute value of curvature
1) Average based filtering: Rule out noises(false positives) + variety in angle changes
- Maxima of curvatures and minima of speed
- Use thresholds to separate the data into two regions for global extrema
- Use hybrid fit generation scheme to eliminate false positives
- The reason why using only curvature data cannot be enough
- The reason why using only speed data cannot be enough
2) Generating hybrid fits
- Computing vertex certainties
- Generating a set of hybrid fits
- Selecting the best fit
- Handling curves: (this is hart part to understand.)
2. Beautification
: make the output visually more appealing without changing its meaning
- Vertex detection
- Corner of a stroke = high local curvature
- Combining stroke direction, curvature and speed data
ex) corner: minimal of speed or maxima of the absolute value of curvature
1) Average based filtering: Rule out noises(false positives) + variety in angle changes
- Maxima of curvatures and minima of speed
- Use thresholds to separate the data into two regions for global extrema
- Use hybrid fit generation scheme to eliminate false positives
- The reason why using only curvature data cannot be enough
- The reason why using only speed data cannot be enough
2) Generating hybrid fits
- Computing vertex certainties
- Generating a set of hybrid fits
- Selecting the best fit
- Handling curves: (this is hart part to understand.)
3. Basic recognition
: interpret the strokes
4. Evaluation
- 13 subjects
5. My opinion
I think this is similar to ShortStraw, but it is much mathematical approach.
Nice explanation with appropriate graph. Your highlight notes emphasis the main idea of this paper. This paper shows an good example on corner finder based on curvature and speed.
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