Displaying 3D images: algorithms for single-image random-dot

A new, simple, and symmetric algorithm can be implemented that results in higher levels of detail in solid objects than previously possible with autostereograms. In a stereoscope, an optical instrument similar to binoculars, each eye views a different picture and thereby receives the specific image that would have arisen naturally. An early suggestion for a color stereo computer display involved a rotating filter wheel held in front of the eyes. In contrast, this article describes a method for viewing on paper or on an ordinary computer screen without special equipment, although it is limited to the display of 3D monochromatic objects. (The image can be colored, say, for artistic reasons, but the method we describe does not allow colors to be allocated in a way that corresponds to an arbitrary coloring of the solid object depicted.) The image can easily be constructed by computer from any 3D scene or solid object description

Investigating collaborative annotation on slate PCs

Mobile reading is becoming evermore popular with the introduction of eInk devices such as the Kindle, as well as the many reading applications available on slate PCs and cellular handsets. The portable nature and large storage capacity of these modern mobile devices is making reading a more technology orientated activity. One aspect of mobile reading that has been given surprisingly little attention is collective reading - which is a common activity with paper documents. We investigate the support of group reading using slate PCs, focussing on collective annotation. In the past, desktop PCs have proved inferior in many ways for reading, when compared to paper. Notably, user evaluations of our new system, BuddyBooks, demonstrate that the slate PC form factor can, in contrast, provide advantages for group reading. While annotation practices change with the new format, coordinating within the group can be improved when touch-interaction is carefully exploited

Unreliable numbers: error and harm induced by bad design can be reduced by better design

Number entry is a ubiquitous activity and is often performed in safety- and mission-critical procedures, such as healthcare, science, finance, aviation and in many other areas. We show that Monte Carlo methods can quickly and easily compare the reliability of different number entry systems. A surprising finding is that many common, widely used systems are defective, and induce unnecessary human error. We show that Monte Carlo methods enable designers to explore the implications of normal and unexpected operator behaviour, and to design systems to be more resilient to use error. We demonstrate novel designs with improved resilience, implying that the common problems identified and the errors they induce are avoidable

Co-reading: investigating collaborative group reading.

Collaborative reading, or co-reading as we call it, is ubiquitous—it occurs, for instance, in classrooms, book-clubs, and in less coordinated ways through mass media. While individual digital reading has been the subject of much investigation, research into co-reading is scarce. We report a two-phase field study of group reading to identify an initial set of user requirements. A co-reading interface is then designed that facilitates the coordination of group reading by providing temporary ‘Point-out’ markers to indicate specific locations within documents. A user study compared this new system with collaborative reading on paper, with a positive outcome; the differences in user behavior between paper and the new interface reveal intriguing insights into user needs and the potential benefits of digital media for co-reading

Human factors and missed solutions to Enigma design weaknesses

The German World War II Enigma suffered from design weaknesses that facilitated its large-scale decryption by the British throughout the war. The author shows that the main technical weaknesses (self-coding and reciprocal coding) could have been avoided using simple contemporary technology, and therefore the true cause of the weaknesses is not technological but must be sought elsewhere. Specifically, human factors issues resulted in the persistent failure to seek out more effective designs. Similar limitations seem to beset the literature on the period, which misunderstands the Enigma weaknesses and therefore inhibits broader thinking about design or realising the critical role of human factors engineering in cryptography

Usability Analysis with Markov Models

How hard to users to find interactive devices to use to achieve their goals, and how can we get this information early enough to influence design? We show that Markov modeling can obtain suitable measures, and we provide formulas that can be used for a large class of systems. We analyze and consider alternative designs for various real examples. We introduce a “knowledege/usability graph,” which shows the impact of even a smaller amount of knowledge for the user, and the extent to which designers' knowledge may bias their views of usability. Markov models can be built into design tools, and can therefore be made very convenient for designers to utilize. One would hope that in the future, design tools would include such mathematical analysis, and no new design skills would be required to evaluate devices. A particular concern of this paper is to make the approach accessible. Complete program code and all the underlying mathematics are provided in appendices to enable others to replicate and test all results shown