4 Tactile Perception Limitations Resolution of human fingertip: 25 dpi Tactual field of perception is no bigger than the size of the fingertips of two hands Color information is replaced by texture information Visual bandwidth is 1,000,000 bits per second, tactile is 100 bits per second
Resolution Study 5.35mm1 mm2 mm On average, blind participants could sense 1 mm separation but no smaller. On average, sighted participant could sense 1.5 mm separation but no smaller.
Blind Spatial Perception Tactile perception can lead to a “spatial” model in the brain.
Tactile Graphics Printing Embossing Printer Thermoform Swell Paper 9
10 Tiger Embosser 20 dpi (raised dots per inch) 7 height levels (only 3 or 4 are distinguishable) Prints Braille text and graphics Prints dot patterns for texture Invented by a blind physicist, John Gardner
16 Available Books Computer Architecture: A Quantitative Approach, 3 rd Edition 25 minutes per figure (230 figures)Computer Architecture: A Quantitative Approach, 3 rd Edition Advanced Mathematical Concepts, Precalculus with Applications 6.3 minutes per figure (1,080 figures)Advanced Mathematical Concepts, Precalculus with Applications An Intoduction to Modern Astrophysics 10.2 minutes per figure (467 figures)An Intoduction to Modern Astrophysics Discrete Mathematical Structures 8.8 minutes per figure (598 figures)Discrete Mathematical Structures Introduction to the Theory of Computation, 2 nd Edition 13.3 minutes per figure (180 figures)Introduction to the Theory of Computation, 2 nd Edition
17 TGA Workflow Advantages –Much faster production –Batch processing instead of one figure at a time –Much tedious work is avoided Disadvantages –May be of lower quality than custom translation –A lot of technology needs to be mastered
18 One-offs vs. Mass Production 1916 Woods Dual Power Model T 1906 Reo
Tactile Graphics with a Voice: using QR codes to access text in tactile graphics C.M. Baker, L.R. Milne, J. Scofield, C.L. Bennett, RE Ladner. Proceedings of the 16th international ACM SIGACCESS conference on Computers. ASSETS 2014. 20
SilentVerbalFinger Pointing Line97% 93% Parabola93%95% Triangle88% 90% Bar Chart73%70%79% All Tasks88% 89% Accuracy 28
4 preferred silent –To be honest, I use screen readers every day and I am so sick of electronic noise. 4 preferred finger pointing –I like the concept of the finger pointing. I feel more confident that since it looks for a finger it’s getting the right QR code if you have multiple on the same page. 2 preferred verbal –The other thing I like about Verbal mode is that every time I hear a zero I think so I need to move it a little bit Preference 29
In a study of 82 images from a pre-calculus textbook, on average Braille took up more space –Braille was larger in 326 out of 626 labels Braille labels: 327 sq. mm QR codes: 225 sq. mm Braille comparison 30