Mahnas Jean Mohammadi-Aragh

MoireTrees: visualization and interaction for multi-hierarchical data

Visualizing hierarchical data is one of the core areas of information visualization. Most of these techniques focus on single hierarchies—hierarchies with a single root element and a single path to each element. In contrast, this work focuses on the browsing of multi-hierarchies—hierarchies with multiple roots or multiple paths per element. A radial focus+context display algorithm and interaction methods are introduced to explore such multi-hierarchical data. A series of examples demonstrate the effectiveness of our new visualization.

Noise-Adjusted Principle Component Analysis For Hyperspectral Remotely Sensed Imagery Visualization.

Introduction In recent years, hyperspectral imaging has been developed in remote sensing, which uses hundreds of co-registered spectral channels to acquires images for the same area on the earth. Its high spectral resolution enables researchers and scientists to detect features, classify objects, and extract ground information more accurately. PCA [1] is a typical approach for high-dimensional data analysis, which assembles the major data information into the first several principal components (PCs) based on variance maximization. However, variance is not a good criterion to rank the data features because part of the variance may be from noise. The noise should be whitened before PCA, which is equivalently to rank the PCs in terms of signal-to-noise ratio. The resultant technique is called Noise-Adjusted Principal Component Analysis (NAPCA) [2]. In our research, NAPCA is employed to visualize images taken by Hyperion, the first spaceborne hyperspectral sensor onboard NASA’s EO-1 satellite.

Visualization of computer-modeled forests for forest management

Forest management is a costly and time-consuming activity. Remote sensing has the potential to improve the process by making it cheaper and more efficient, but only if appropriate characteristics can be determined from computer-models. This paper describes the implementation of a forest visualization system and a corresponding user study that tests the accuracy of parameter estimation and forest characterization. The study uses data obtained from field-surveys to generate a computer-modeled forest. Five different stands were tested. Based on the quantitative results obtained, generally, there is no statistically significant difference in parameter estimation when comparing field-recorded videos and computer-generated videos.

Improving student writing through multiple peer feedback

This paper describes the design of a study to examine the effects of various types of feedback and revision on student writing quality improvement in a first-year engineering course. We apply the previous work of Cho and MacArthur that showed that multiple peer feedback is superior to single peer and single expert feedback in improving student writing quality. We extend their work to examine the effects of in-class instruction on giving peer feedback, and also examine the effect of giving (rather than receiving) feedback on student revisions. Preliminary findings from this study will be presented at the conference.

Work in progress — Effect of departmental culture on ePortfolios for graduate engineering programmatic assessment

This “Work In Progress” is part of a larger study investigating ePortfolio use for graduate assessment in engineering programs. ePortfolios have been used in a variety of applications ranging from undergraduate assessment to graduate student work showcases and most recently for graduate program assessment. Little work to date has been done that specifically addresses graduate assessment in engineering. Our study helps fill this gap by examining the results of ePortfolio implementations in three separate engineering graduate programs at a large research institution located in the southeast United States. The ePortfolios studied were designed in Fall 2010 and implemented in Spring 2011. During the design phase, anecdotal evidence of distinct departmental cultures emerged. The cultures appeared to have an effect on the final ePortfolio designs. This work formally examines departmental culture from an “insider” perspective and determines the relationship, if any, between departmental culture and perceptions of ePortfolios.

Visualizing and Interacting with Multi-Tree Hierarchical Data

This work focuses on visualizing highly cyclic hierarchical data. A user interface is discussed and its interaction is illustrated using a recipe database example. This example showcases a database with multiple categories for each recipe (database entry).

Human factor integration into the development of a realistic tree-rendering system based on lidar remote sensing

This paper introduces application of the Cave Automatic Virtual Environment (CAVE) to forest visualization and user studies which were designed to gain insight into human factors for system development. This interdisciplinary research project was undertaken by the Visualization, Analysis, and Imaging Laboratory and the Department of Forestry at Mississippi State University (MSU). The purpose was to create a forest management tool for remote examination of stands in a stereoscopic environment which allows users to observe and interact with realistic virtual stands. The datasets used in this study include measurements such as total height, Diameter at the Breast Height (DBH), and crown radii. The datasets were directly and indirectly generated from Light Detection and Ranging (LiDAR) data. The datasets from immature (eight-years-old) high density and mature (40-years-old) low density loblolly pine (Pinus taeda) stands were used to generate three types of tree models. These three models represent trees in different graphic-complexities and thus interactivity. In general, higher fidelity is preferred in visualization. However, there is a trade-off between graphic details and interaction speed. To determine an optimal model, a user study was designed to examine the influence photo-reality and interactivity have on the viewers perception. Human subjects recruited from MSUs Department of Forestry will explore virtual stands rendered with one of the tree models in the CAVE and estimate forest parameters.

Text Entry Via Palm™ Handheld in an Immersive Virtual Environment

There is a need for text entry capability in immersive virtual reality environments such as the CAVE®. Existing text entry devices distract users from the immersive experience at best, and remove them from it at worst. An implementation of a text entry method using a handheld personal digital assistant (PDA) to communicate with a CAVE® application is described. To reduce the complexity of navigating with one device and entering text with another, several navigation methods using a Palm™ handheld have been devised. Their merits are discussed. One of these, a point-and-stroke navigation method, is simple, effective, and well suited to any application using a handheld computer for navigation inside a mappable environment.