Lori L. Scarlatos

Hierarchical triangulation using cartographic coherence

Abstract Triangulated Irregular Networks (TINs) approximate surfaces for many applications. For those that require different resolutions, TINs may be stored in a hierarchical structure. In the past, techniques have been emphasized where a coarse triangulation is refined by focusing on plane geometry using very little of the surface data. For example a new point is introduced where the surface deviates farthest from the plane of the triangle, and the triangle is subdivided into three new ones. Variants of Delaunay triangulations have also been used. We propose a technique where we take into account that deviations of a terrain surface from planarity do not occur at isolated points but they occur coherently along ridges, valleys, peaks and other features. If, for example, a ridge cuts across a triangle, that triangle is divided by a line along the ridge and the remaining quadrilateral gets split into the two most nearly equilateral triangles. In this way the number of very thin triangles (slivers) is significantly reduced. Such triangles produce undesirable effects in animation. In addition the number of levels of the TIN tree is reduced which speeds up searching within the data structure. Our tests on digital elevation data have confirmed the above theoretical expectations. Results show that average “sliveriness” with our new method is between 1 5 and 1 10 that of triangulations produced with DeFlorianis first method. The resulting number of levels in the hierarchy is about one third and although there is an increase in the number of descendants at each level, the total number of triangles is also lower.

Hierarchical triangulation using terrain features

A hierarchical triangulation built from a digital elevation model in grid form is described. The authors present an algorithm that produces a hierarchy of triangulations in which each level of the hierarchy corresponds to a guaranteed level of accuracy. The number of very thin triangles (slivers) is significantly reduced. Such triangles produced undesirable effects in animation. In addition the number of levels of the triangulated irregular network (TIN) tree is reduced. This speeds up searching within the data structure. Tests on data with digital elevation input have confirmed the theoretical expectations. On eight such sets the average sliveriness with the method was between 1/5 and 1/10 of old triangulations and number of levels was about one third. There was an increase in the number of descendants at each level, but the total number of triangles was also lower.<<ETX>>

Optimizing triangulations by curvature equalization

An algorithm that attempts to improve a triangulation by shifting the vertices so that curvature within the triangles is nearly equal is presented. Unnecessary triangles are removed. The method is an effective way of guaranteeing that the triangle vertices are points of higher curvature, and that the triangle edges correspond to distinctive edges on the surfaces. Triangulations of surfaces with constant curvature-and hence no distinctive features-will gain nothing from this or any other optimization algorithm. As demonstrated by the results, the techinque of moving triangle vertices can improve some triangulation models. Greatest improvements occur with surfaces characterized by sharp edges, such as the pyramid and ridge models. Less improvement occurs on models that already approximate the surface topology and/or have less distinctive features.<<ETX>>

An application of tangible interfaces in collaborative learning environments

Over the years, educators and government officials have searched for ways to improve learning in our schools, particularly in the areas of math and science. Many have come to recognize that collaborative activities, learning through play, and teacher guidance can help children to get over their initial fears and even begin to enjoy these subjects. Yet, at the same time, shrinking school budgets are making it harder to support these approaches to learning. Tangible Interfaces for Collaborative Learning Environments (TICLE) was conceived in response to this need [Scarlatos 2002].

Designing interactive multimedia (panel)

This paper presents contrasting metaphors and paradigms for designing interactive media interfaces. Multimedia interface designers and researchers with diverse backgrounds discuss their own design approaches and important design ‘issues. Discussion of these issues is continued beyond this paper through a web site:

The hidden gender effect in online collaboration

Controlled experiment of gender composition on team performance under anonymity.Female-dominated teams are more productive than male-dominated teams.Female students are no more productive than male students.Female students act more collaboratively. It has been argued that the generally positive effect that female participation exerts on team performance ceases to exist under conditions of anonymity. We evaluate this thesis in the context of an online learning environment in which the gender of fellow student team members was not disclosed to subjects. To circumvent selection effects in the composition of teams we employed an experimental design in which female and male students were randomly assigned to teams of varying gender composition. Against expectations, we find that under anonymity gender composition continues to impact team performance, with all-female teams being most productive. Counter-intuitively, this team effect occurred in our study without female students individually being more productive than their male counterparts. These findings indicate that the presence of females on anonymous teams can have a hidden effect on the productivity of other team members. Our results underscore that despite face-to-face interaction in higher education increasingly being substituted by Internet-enabled communication, a students social environment continues to impact academic learning in important ways.

Mind Reader: Designing for More Intimate Social Play in Video Games

Socializing is one of the main reasons that people play games [14]. However, co-located video games often move the focus toward a visual display and personal input devices. This paper looks at how we can bring the focus back on the co-players providing for more intimate social play without losing the advantages of digital games and visual display. Such games may provide social/relational benefits and increased enjoyment as well as may be of use for social learning, teambuilding, and therapy. The design of our game, Mind Reader, attempts to both learn from non-digital games as well as exploit the potential of mobile devices to create a more social form of video game. The game was built around two main features: face-to-face play and a shared physical space designed to promote social gameplay. We then present a way to test this new form of gameplay against traditional mobile gaming to determine its effect on social interaction.

SUPPORTING COLLABORATIVE LEARNING IN A VIRTUAL REALITY ENVIRONMENT

As computers become more capable of identifying the physical components of human behavior, it becomes less necessary to adjust our behavior to conform to the computer’s requirements. Such capabilities are particularly useful when children are involved, and make using computers in education all the more appealing. Here we look at a system designed to track children as they collaborate on a learning project within a virtual reality environment, giving feedback and limited guidance to encourage progress and problem solving. The learning projects require users to move freely about the environment, thus stimulating the kinesthetic sense. These learning projects encourage participants to access new perspectives, thereby allowing them to perceive the problem in multiple ways. As part of an environment which supports and encourages collaboration, the potential educational benefit is significant.

Book Review: The One World Schoolhouse: Education ReimaginedThe One World Schoolhouse: Education Reimagined, by KhanSalman, New York, NY: Twelve, Hachette Book Group, 2012.

Late last year, the New York Times designated 2012 as “The Year of the MOOC” (November 2, 2012). News about MOOCs has ranged from overly optimistic visions of education for all (“The Most Important Education Technology in 200 Years,” Technology Review’s Business Report, November 2, 2012) to dire predictions of disaster for the field of education (“As MOOC Debate Simmers at San Jose State, American U. Calls a Halt,” Chronicle of Higher Education, May 9, 2013). Most of the news focuses around three major organizations established for this purpose: Coursera, Udacity, and EdX. Among all the chatter, it is easy to forget about one of the earlier pioneers of open online education for the masses: Khan Academy. Khan Academy was founded in 2006 by Salman Khan, a former engineer and hedge fund analyst with an MBA from Harvard Business School. Khan Academy is a free educational resource, consisting of short videos and selfchecking quizzes, designed primarily to help secondary school students in their academic subjects. With his new book, The One World School House: Education Reimagined, Khan presents an educational philosophy that has driven his efforts at the Khan Academy and fuels his vision of the future for education. The tone of Khan’s book is set immediately in the Introduction, which begins with an overview of what he believes to be the current crisis in education. He provides a brief history of how he came to devote his life to educating young people, and how Khan Academy grew from a family project to an international non-profit. Tying theses together, he summarizes his vision of how we can fix education, by giving students the resources (and flexibility) to master topics that they don’t yet grasp and thereby filling the holes in their understanding. The book itself is divided into four parts. The first part, “Learning to Teach,” describes the lessons that Mr. Khan learned in his attempts to tutor his niece. Nadia, a normally good student, was being prevented from going into the honors

Detecting data visualization preferences using games

In visualizations of large multivariate data sets, discrete data can be effectively represented using glyphs. Glyphs have the advantage of allowing for rapid visual comparison, using differing visual dimensions to represent the different variables in the data. Some types of glyphs accommodate even more variables by using shape to represent the data. Yet the characteristics of these shapes may have underlying perceptual meanings. The purpose of this study was to determine whether certain shape characteristics are commonly viewed as good or bad. We conducted a study using two methods to gather data: a traditional survey, and a casual game. The results of this study strongly suggest that there are certain shape characteristics that are generally perceived as positive/negative, although they are not necessarily what might be expected.