IEEE Computer Graphics and Applications

PrePrint: Visual Analysis of Flow Features Using Information Theory

Unsteady scientific data is one of the top challenges in visualization, as a huge amount of information has to be displayed. $\epsilon$-Machines are an information-theoretic concept that compress the dynamics in the data set to a finite state machine, where nodes represent local flow patterns and edges transitions between them. In this paper, we propose several enhancements to the fundamental $\epsilon$-machine representation to identify interesting time intervals, analyze the evolution of unusual local dynamics and track features over time. Automatically abstracting information from the original data, as provided by these tasks, is a first step towards knowledge-assisted visualization. Successive findings in the analysis process can be used to provide subsequent users with knowledge gained in earlier research, resulting in a knowledge-assisted system for the analysis of unsteady flow features based on information theory.

PrePrint: Virtual reality, a serious game for understanding performance and training players in sport

Understanding and increasing performance in sports is difficult as many different biomechanical, physiological and psychological factors come into play during competition. To understand and consequently improve performance it is important to isolate contributing factors to determine their role in player performance. Video playback, the oft chosen method for studying this, does not permit this type of in-depth analysis. For example, the lack of control an observer has over what and how they see something is a major flaw. The aim of this paper is to present the interest of serious games and interactive immersive virtual reality (VR) as the new preferred method for understanding sports performance from a behavioral neuroscience perspective. By showcasing two practical examples which use VR and sophisticated animation software we aim to demonstrate how this technology can help us understand how the information picked up from the visual displays informs a player’s future course of action.

Presented By:

NEC

Ads by Pheedo

PrePrint: AniViz: A Template-based Animation Tool for Volume Visualization

We introduce AniViz – a tool for making visualization animations. The design of AniViz is mainly based on two principles. First, AniViz allows the user to make animations while exploring the data. Second, AniViz provides a set of motion templates for the user to create desirable effects as instances of those templates. AniViz also provides the user with a set of operators to edit an instance or combine multiple ones into a sequence of effects. The user can fine tune parameters associated with an instance or a sequence in a keyframe style. The length of each segment in the animation may be specified by the user or automatically allocated by AniViz based on a distance metric. AniViz offers these functionalities through a simple and easy-to-use interface. We demonstrate AniViz with several volume visualization applications.

PrePrint: The Impact of the OCEAN Personality Model on the Perception of Crowds

Most current crowd simulators animate homogeneous crowds, but include underlying parameters that can be tuned to create variations within the crowd. These parameters, however, are specific to the crowd models and may be difficult for an animator or naïve user to use. We propose mapping these parameters to personality traits. In this paper, we extend the HiDAC (High-Density Autonomous Crowds) system by providing each agent with a personality model. We use the OCEAN personality model as a basis for agent psychology. To each personality trait we associate nominal behaviors; thus, specifying personality for an agent leads to an automation of the low-level parameter tuning process. We describe a plausible mapping from personality traits to the existing behavior types and analyze the overall emergent crowd behaviors. Finally, we validate our mapping by user studies that assess the perception of the traits in the animations illustrating such behaviors.

PrePrint: Insight into 3D goal-directed movements through a division into meaningful movement phases

The measures that are currently used to evaluate users’ performances on interaction tasks in virtual environments often do not provide sufficient information for how to improve these interactions. The current paper proposes a new method for analyzing 3D goal-directed movements based on dividing them into meaningful phases. We apply the method to experimental data that we have collected earlier for a 3D task that resembles a standardized 2D multi-directional pointing task (ISO 9241-9). Our analysis demonstrates how a more detailed insight into 3D goal-directed movements can be gained. We claim that this analysis can help to better identify weak and strong points of input devices or interaction techniques.

PrePrint: EasyToy: A Plush Toy Design System Using Editable Sketching Curves

EasyToy is an industrial-strength plush toy design system, targeting novices who want to design sophisticated toy models by themselves, simply and quickly. The fundamental tool in EasyToy is editable sketching curves, which combine the advantages of both natural expression of free-form strokes and the controllability of B-spline curves. A distinct feature in EasyToy system is that each sketching curve can be continuously edited to refine the initial rough idea. Using a small set of simple tools, EasyToy easily constructs sophisticated toy models comparable with those by professional systems. Informal user study has been conducted in a two-year period. The results are inspiring: using EasyToy, the design intent of users can be addressed fluently by mimicking traditional paper-and-pencil-based 2D/3D sketches, without distraction and interruption appearing often during the modeling processes in previous design systems.

PrePrint: Knowledge-Assisted Visualization and Segmentation of Geologic Features using Implicit Surfaces

We present a technique that allows knowledge-assisted interactive visualization and segmentation of geologic surfaces. Our method employs domain knowledge about the structure and topology of geologic features in seismic data in order to steer dynamic surfaces into those features. Specialized attributes guide evolving surfaces by adapting to the known shape of geologic features. Geometric, topological, and geologic information help steer growth and can be rendered on the evolving surface, which allows knowledge to be inferred during the process. Our technique is implemented in a 3-D visualization environment that contains domain information about geologic features in seismic data and allows users to interactively steer segmentations based on visual sources of information and knowledge. Results from a user study are presented that show the ability of this technique to transfer domain knowledge to non-experts, which allows for intuitive segmentation of geologic features.

IEEE Computer Graphics and Applications - November/December 2009 (Vol. 29, No. 6)

IEEE Computer Graphics and Applications

PrePrint: Knowledge-Based 3D Reconstruction and Visualization of Human Ribcage and Lungs

To help mimic some of the useful features of CT scans for early detection of diseases like lung cancer at a fraction of the cost, a knowledge‐assisted interactive 3D ribcage and lung reconstruction algorithm is proposed. The ribcage and lung reconstructions are both based on the typical PA (rear) and Lateral (side) X‐ray images that are already being acquired during preemptive screenings for lung cancer. Shared domain knowledge of human anatomy and solid modeling techniques are combined with knowledge automatically extracted from the X‐ray images through computer vision algorithms to transform a series of primitive template meshes into reconstructed ribs and lungs despite the fact that much of the 3D information is lost during the X‐ray process. An example of how the reconstructed lung geometry can be used to clip the portion of an approximate volume reconstruction to provide a supplementary interface to search for potential diseased areas is presented.

PrePrint: Natural Character Posing from a Large Motion Database

This paper presents NAT-IK, a new interactive inverse kinematics scheme that can robustly and interactively generate natural poses in a large human-reachable space. NAT-IK employs an adaptive kd-clustering algorithm to select a representative frame set from a large motion database, and a sparse approximation algorithm to accelerate the training and posing processes. The model training process needs to be done only once. The training results contain 30MB of data, which can be conveniently imported into existing animation packages.

PrePrint: Navigation Tools for Augmented CAD Viewing

The creation of a computer aided design (CAD) model is the first step in the development of any modern physical product. This model will be used during the complete life cycle of the product: prototyping, fabrication, maintenance and upgrade. During the construction, a discrepancy between the model and the object can occur. In order to maintain and upgrade the object it is mandatory to have a model that represents the reality. So that one can have an up-to-date model one has to verify it and sometimes update it. We propose a scalable solution where CAD software has been augmented with pictures of the object. Still images have been aligned to the model allowing visualization of the model and the object at the same time. This creates what can be called a mixed view. The virtual camera that renders the model in a mixed view is restricted by the still image because the alignment between the image and the model has to be maintained. We developed tools to navigate in this mixed world. We transposed the zoom and pan from 2D user interfaces in order to navigate in the mixed view. Additionally we introduced tools for intuitive navigation within a set of mixed views.

PrePrint: Wii Remote and Beyond: Using Spatially Convenient Devices for 3DUIs

The Nintendo Wii Remote (Wiimote) has been used as an input device in 3DUIs but differs from general-purpose input hardware, typically found in research labs and commercial applications. Despite this, there has been no systematic evaluation of the device in terms of what it offers to 3DUI designers. Our experience has led to the conclusion that the Wiimote is an imperfect harbinger for a new class of spatially convenient devices, classified in terms of: spatial data, functionality and commodity design. This tutorial presents techniques for using the Wiimote in 3DUIs. The strengths of the device and methods to compensate for its limitations are also discussed, with implications to future spatially convenient devices. We begin with a detailed description of the Wiimote. This is followed by methods of interpreting the data as demonstrated by work at the Interactive Systems and User Experience Lab at UCF. With these methods, the uses of the Wiimote in designing for the universal tasks of 3D interaction are reviewed and guidelines presented. We conclude with a discussion of the future of spatially convenient input devices.

PrePrint: Ringing: Frugal subdivision of curves and surfaces

J-spline subdivisions iteratively refine a polygon by inserting a vertex in the middle of each edge and then moving each vertex to an affine combination of five consecutive vertices. Applying d refinement steps to a control polygon of n vertices requires temporary storage space for (n-5)2d+5 vertices. Rendering each span independently reduces temporary storage requirement (footprint) to 2d+5 vertices, but increases computation. The ringing approach introduced here reduces the footprint to 4d vertices. We describe an efficient implementation, show applications to surfaces and animations, and report timings comparing CPU and GPU implementations of ringing with the global and per-span approaches.

PrePrint: Volumetric Ambient Occlusion

This paper presents a new GPU-based algorithm to compute ambient occlusion. We first examine how ambient occlusion is related to the physically founded rendering equation. The correspondence is made by introducing a fuzzy membership function that defines what ``near occlusions'' mean. Then we develop a method to calculate ambient occlusion in real-time without any pre-computation. The proposed algorithm is based on a novel interpretation of ambient occlusion that measures how big portion of the tangent sphere of the surface belongs to the set of occluded points. The integrand of the new formula has low variation, thus can be estimated accurately with a few samples. Thus, the algorithm can effectively be used in real-time systems and games to cheaply approximate global illumination effects.

PrePrint: Application-Driven Compression for Visualizing Large-Scale Time-Varying Volume Data

In many areas of science and engineering, the desires to study a problem at the highest possible resolution have led to an explosive growth of data. It is imperative to reduce the data to a manageable scale for analysis and visualization. For high-precision floating-point data, compressing the data solely based on values can only achieve a limited saving. Further reduction is possible with the fact that usually only a smaller subset of the data is of interest in analysis. In this paper, we present an application-driven approach to compressing large-scale time-varying volume data. Our method identifies a reference feature to partition the data into space-time blocks, which are compressed with various precisions depending on their association to the feature. Runtime decompression is performed with bit-wise texture packing and deferred filtering. We show that our method achieves high compression rates and interactive rendering while preserving fine details surrounding regions of interest. Such an application-driven approach points us to a promising direction for coping with the large data problems facing computational scientists.

PrePrint: Learning Blood Management in Orthopedic Surgery through Gameplay

In this paper, we report our experience in the design and implementation of a serious game for learning orthopedic surgery. We focus on the training of blood management skills which are important for safe orthopedic operations. A wide range of state-of-the-art graphics technologies are employed to provide an interactive and realistic virtual environment. Game elements are also integrated into the system, including task-oriented scenarios, time attack scenarios, bonus, game levels and performance evaluation tools. Experiments are conducted to study the effect of the proposed system, in terms of completion time and off-target contacts, on learning psychomoter skills in blood management.