Touch Screens

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  • Touch Screens

    1. 1. Precise Selection Techniques for Multi-Touch Screens By: IQxplorer
    2. 2. Selecting a small target is very HARD! CHI 2006
    3. 3. Small target size comparison <ul><li>Average finger ~ 15 mm wide </li></ul>CHI 2006 Target UI element Width (abstract screen) Width 17” screen 1024x768 Width 30” screen 1024x768 Close button 18 pixels 6 mm (40% of finger) 10.8 mm (66% of finger) Resize handle 4 pixels 1.34 mm (9% of finger) 2.4 mm (16% of finger)
    4. 4. Touchscreen Issues <ul><li>Finger >>> Target </li></ul><ul><li>Finger occludes the target </li></ul><ul><li>Fingers/hands shake and jitter </li></ul><ul><li>Tracking can be noisy (e.g. video) </li></ul><ul><li>No hover state (hover == drag) </li></ul>CHI 2006
    5. 5. Previous Work <ul><li>Solutions based on single touch interfaces and complex on-screen widgets: </li></ul><ul><li>Albinsson, P. A. and Zhai, S. “High Precision Touch Screen Interaction.” (CHI ’03) </li></ul>CHI 2006 Sears, A. and Shneiderman, B. “High Precision Touchscreens: Design Strategies and Comparisons with a Mouse.” (’91)
    6. 6. Dual Finger Selections <ul><li>Multi-touch techniques </li></ul><ul><li>Single fluid interaction </li></ul><ul><ul><li>no lifting/repositioning of fingers </li></ul></ul><ul><li>Design guidelines: </li></ul><ul><ul><li>Keep simple things simple. </li></ul></ul><ul><ul><li>Provide an offset to the cursor when so desired. </li></ul></ul><ul><ul><li>Enable user controlled control-display ratio. </li></ul></ul>CHI 2006
    7. 7. Simulating Hover State <ul><li>Extension of the “area==pressure” idea (MacKenzie and Oniszczak, CHI 1998) </li></ul><ul><li>Problem: </li></ul><ul><ul><li>LARGE area difference  reliable clicking </li></ul></ul><ul><ul><li>SMALL movement (i.e. SMALL area difference)  precise and accurate clicking </li></ul></ul>CHI 2006
    8. 8. SimPress (Simulated Pressure) <ul><li>Clicking gesture – “finger rocking” </li></ul><ul><li>Goal: </li></ul><ul><ul><li>Maximize ∆ touch area </li></ul></ul><ul><ul><li>Minimize ∆ cursor location </li></ul></ul>CHI 2006
    9. 9. <ul><li>Top Middle Cursor </li></ul><ul><li>Large ∆ touch area </li></ul><ul><li>Small ∆ cursor loc. </li></ul><ul><li>Center-of-Mass Cursor </li></ul><ul><li>Large ∆ touch area </li></ul><ul><li>Large ∆ cursor loc. </li></ul>SimPress Cursor Placement CHI 2006
    10. 10. SimPress in Action CHI 2006
    11. 11. Dual Finger Selections <ul><li>Offset </li></ul><ul><li>Midpoint </li></ul><ul><li>Stretch </li></ul><ul><li>X-Menu </li></ul><ul><li>Slider </li></ul><ul><li>Primary finger  cursor position & click </li></ul><ul><li>Secondary finger  cursor speed or C/D </li></ul>CHI 2006
    12. 12. Dual Finger Offset CHI 2006 <ul><li>Fixed offset WRT finger </li></ul><ul><li>Ambidextrous control </li></ul>
    13. 13. Dual Finger Midpoint CHI 2006 <ul><li>Cursor  ½ distance between fingers </li></ul><ul><li>Variable speed control </li></ul><ul><li>Max speed reduction is 2x </li></ul><ul><li>Dead spots on screen! </li></ul>
    14. 14. Dual Finger Stretch <ul><li>Inspired by ZoomPointing (Albinsson & Zhai,‘03) </li></ul><ul><li>Primary finger  anchor </li></ul><ul><li>Secondary finger </li></ul><ul><ul><li>defines the zooming area </li></ul></ul><ul><ul><li>scales the area in all directions away from the anchor </li></ul></ul>CHI 2006
    15. 15. Dual Finger Stretch CHI 2006 <ul><li>Offset is preserved after selection! </li></ul>
    16. 16. Zooming Comparison <ul><li>Bounding Box Zoom </li></ul><ul><ul><li>Fingers placed OFF target </li></ul></ul><ul><ul><li>Target distance increases w/ zoom </li></ul></ul><ul><li>“ Stretch” Zoom </li></ul><ul><ul><li>Primary finger placed ON target </li></ul></ul><ul><ul><li>Same motion = 2x zoom </li></ul></ul>CHI 2006
    17. 17. Dual Finger X-Menu <ul><li>Crossing Menu (no buttons/no clicks) </li></ul><ul><ul><li>4 speed modes </li></ul></ul><ul><ul><li>2 helper modes </li></ul></ul><ul><li>Cursor notification widget </li></ul><ul><ul><li>Eyes-free interaction </li></ul></ul><ul><li>Freezing cursor </li></ul><ul><ul><li>Quick offset setup </li></ul></ul><ul><ul><li>Eliminate errors in noisy conditions </li></ul></ul><ul><li>Helpers: </li></ul><ul><ul><li>Snap – Remove offset </li></ul></ul><ul><ul><li>Magnification Lens </li></ul></ul>CHI 2006
    18. 18. Dual Finger X-Menu CHI 2006
    19. 19. Dual Finger X-Menu with Magnification Lens CHI 2006
    20. 20. Dual Finger Slider CHI 2006 Normal Slow 4X Slow 10X Freeze Snap
    21. 21. Dual Finger Slider CHI 2006
    22. 22. Multi-Touch Table Prototype <ul><li>Back projected diffuse screen </li></ul><ul><li>IR vision-based tracking </li></ul><ul><li>Similar to TouchLight (Wilson, ICMI’04) </li></ul>CHI 2006
    23. 23. User Experiments <ul><li>Measure the impact of a particular technique on the reduction of error rate while clicking </li></ul><ul><li>2 parts: </li></ul><ul><ul><li>Evaluation of SimPress clicking </li></ul></ul><ul><ul><li>Comparison of Four Dual Finger Techniques </li></ul></ul><ul><li>Task: </li></ul><ul><ul><li>Reciprocal target selection </li></ul></ul><ul><ul><li>Varying the square target width </li></ul></ul><ul><ul><li>Fixed distance (100 pixels) </li></ul></ul><ul><li>12 paid participants (9 male,3 female, ages 20–40), frequent computer users, various levels of touchscreen use </li></ul>CHI 2006
    24. 24. Part 1: SimPress Evaluation <ul><li>Within subjects repeated measures design </li></ul><ul><li>5 target widths: </li></ul><ul><ul><li>1,2,4,8,16 pxls </li></ul></ul><ul><li>Hypothesis: only 16 pxls targets are reliably selectable </li></ul><ul><li>Results: 8 pixel targets still have ~10% error rate </li></ul>CHI 2006 F (4,44) =62.598, p<0.001
    25. 25. Part 2: Comparison of 4 Dual Finger Selection Techniques <ul><li>Compare: Offset, Stretch, X-Menu, Slider </li></ul><ul><li>Varying noise conditions </li></ul><ul><ul><li>Inserted Gaussian noise: σ =0, 0.5, 2 </li></ul></ul><ul><li>Within subjects repeated measures design: </li></ul><ul><ul><li>3 noise levels x 4 techniques x 4 target widths (1,2,4,8 pxls) </li></ul></ul><ul><ul><li>6 repetitions  288 trials per user </li></ul></ul><ul><li>Hypotheses: </li></ul><ul><ul><li>Techniques that control the C/D will reduce the impact of noise </li></ul></ul><ul><ul><li>Slider should outperform X-Menu </li></ul></ul>CHI 2006
    26. 26. Part 2: Error Rate Analysis <ul><li>Interaction of Noise x Technique </li></ul>CHI 2006 F (6,66) = 8.025, p<0.001
    27. 27. Part 2: Error Rate Analysis CHI 2006 <ul><li>Interaction of Width x Technique </li></ul>F (9,99) =29.473, p<0.001
    28. 28. Part 2: Movement Time Analysis <ul><li>Analysis on median times </li></ul><ul><li>Stretch is ~ 1s faster than Slider/X-Menu (t(11)=5.011, p<0.001) </li></ul><ul><li>Slider similar performance to X-Menu </li></ul>CHI 2006 Missing
    29. 29. Subjective Evaluation <ul><li>Post-experiment questionnaire (5 pt Likert scale) </li></ul><ul><ul><li>Most mental effort: X-Menu (~2.88) </li></ul></ul><ul><ul><li>Hardest to learn: X-Menu ( ~2.09) </li></ul></ul><ul><ul><li>Most enjoyable: Stretch (~4.12), Slider (~4.08) </li></ul></ul><ul><ul><li>No significant differences WRT fatigue </li></ul></ul>CHI 2006
    30. 30. Conclusions and Future Work <ul><li>Top performer & most preferred: Stretch </li></ul><ul><li>Slider/X-Menu </li></ul><ul><ul><li>Comparable error rates to Stretch </li></ul></ul><ul><ul><li>No distortion of user interface </li></ul></ul><ul><ul><li>Cost: ~1s extra </li></ul></ul><ul><li>Freezing the cursor (positive feedback) </li></ul><ul><ul><li>Like “are you sure?” dialog for clicking… </li></ul></ul><ul><li>Possible future SimPress extensions: </li></ul><ul><ul><li>Detect user position/orientation </li></ul></ul><ul><ul><li>Stabilization of the cursor </li></ul></ul>CHI 2006
    31. 31. Questions
    32. 32. Multi-Touch Tabletops <ul><li>MERL DiamondTouch (Dietz & Lehigh, ’01) </li></ul><ul><li>SmartSkin (Rekimoto, ’02) </li></ul><ul><li>PlayAnywhere and TouchLight (Wilson, ’04, ’05) </li></ul>CHI 2006
    33. 33. ANOVA Table CHI 2006 Source df F p Noise (N) (2,22) 20.24 <0.001 Technique (T) (3,33) 169.14 <0.001 Width (W) (3,33) 150.40 <0.001 N x T (6,66) 8.03 <0.001 T x W (9,99) 29.47 <0.001 N x W N x T x W

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