Reducing artifacts in surface meshes extracted from binary volumes

We present a mesh filtering method for surfaces extracted from binary volume data which guarantees a smooth and correct representation of the original binary sampled surface, even if the original volume data is inaccessible or unknown. This method reduces the typical block and staircase artifacts but adheres to the underlying binary volume data yielding an accurate and smooth representation. The proposed method is closest to the technique of Constrained Elastic Surface Nets (CESN). CESN is a specialized surface extraction method with a subsequent iterative smoothing process, which uses the binary input data as a set of constraints. In contrast to CESN, our method processes surface meshes extracted by means of Marching Cubes and does not require the binary volume. It acts directly and solely on the surface mesh and is thus feasible even for surface meshes of inaccessible or unknown volume data. This is possible by reconstructing information concerning the binary volume from artifacts in the extracted mesh and applying a relaxation method constrained to the reconstructed information

Visual Support for the Modeling and Simulation of Cell Biological Processes

This dissertation aims at bringing information visualization closer to the demands of analytical problem solving for the specific domain of modeling and simulating cell biological systems. To this end, main segments of visual support in the domain are identified. For one of these segments, the visual analysis of simulation data, new concepts are developed. First, this includes the visualization of simulation data in the context of data generation. Second, new multiple view techniques for large and complex simulation data are introduced.Diese Arbeit verfolgt das Ziel, Informationsvisualisierung näher an die Anforderungen des Analyseprozesses heranzuführen, mit Blick auf die konkrete Anwendung der Modellierung und Simulation zellbiologischer Systeme. Dazu werden wesentliche Teilbereiche der visuellen Unterstützung identifiziert. Für den Teilbereich der visuellen Analyse von Simulationsdaten werden neue Konzepte entwickelt. Dies beinhaltet zum einen die Visualisierung von Simulationsdaten im Kontext der Datengenerierung. Zum anderen werden neue Multiple-View-Techniken für große und komplexe Simulationsdaten vorgestellt

Stochastic collocation for optimal control problems with stochastic pde constraints

pre-printWe discuss the use of stochastic collocation for the solution of optimal control problems which are constrained by stochastic partial differential equations (SPDE). Thereby the constraining SPDE depends on data which is not deterministic but random. Assuming a deterministic control, randomness within the states of the input data will propagate to the states of the system. For the solution of SPDEs there has recently been an increasing effort in the development of efficient numerical schemes based upon the mathematical concept of generalized polynomial chaos. Modal-based stochastic Galerkin and nodal-based stochastic collocation versions of this methodology exist, both of which rely on a certain level of smoothness of the solution in the random space to yield accelerated convergence rates. In this paper we apply the stochastic collocation method to develop a gradient descent as well as a sequential quadratic program (SQP) for the minimization of objective functions constrained by an SPDE. The stochastic function involves several higher-order moments of the random states of the system as well as classical regularization of the control. In particular we discuss several objective functions of tracking type. Numerical examples are presented to demonstrate the performance of our new stochastic collocation minimization approach

Store layout effects on consumer behavior in 3D online stores

Purpose: Positioned in the e-retailing field, this study aims to investigate the effect of the retail store’s atmosphere on consumer behavior in 3D online shopping environments, focusing on store layout as a critical influential factor. Design/methodology/approach: The research uses a mixed research method approach that includes two complementary studies. First, a three-round Delphi study with domain experts is used to develop a store layout classification scheme (Study 1), resulting in five distinct types of store layout. Subsequently, 3D online retail stores that use the five layouts are designed and developed. These serve as treatments of a laboratory experimental design, which is used to assess layout impact on a number of attitudinal and behavioral variables (Study 2). Findings: Five distinct types of store layout have been identified in Study 1, and their distinctive features are presented. The findings of Study 2 indicate that online shopping enjoyment, entertainment and ease of navigation are influenced by the store layout types of 3D online environments. Specifically, the “avant-garde” layout type facilitates the ease of navigation of customers in the store and provides a superior online customer experience. The “warehouse”’ adopts long aisles for the display of products, which simplifies the comparison of products, whereas the “boutique” layout was found to be the best in terms of shopping enjoyment and entertainment. The “department” layout shares many common characteristics with traditional department stores, providing an entertaining and enjoyable store, whereas the “pragmatic” layout emphasizes low system requirements. Practical implications: The paper presents characteristics that make store layouts effective for different aspects of online customers’ experience and identifies opportunities that 3D online store designers and retailers can explore for the provision of enhanced, customized services to online customers. Originality/value: This paper examines recent technological developments in store design and visual merchandising. It identifies five layout types of 3D online stores, which are different from those of brick–and–mortar and 2D online stores, and investigates their impact on consumer behavior. Further, the paper examines how each layout type influences online shopping enjoyment, entertainment, ease of navigation, online customer experience and, in turn, purchase and word-of-mouth intentions. Finally, the paper examines the moderating role of telepresence. Individuals with high sense of telepresence conceive 3D environments as “real” and are more concerned about the attributes that trigger the sense of enjoyment they experience while browsing

Untersuchungen zu nutzerbezogenen und technischen Aspekten beim Langzeiteinsatz mobiler Augmented Reality Systeme in industriellen Anwendungen

Magdeburg, Univ., Fak. für Informatik, Diss., 2009Johannes Tümle

Dynamic Volume Rendering of Functional Medical Data on Dissimilar Hardware Platforms

In the last 30 years, medical imaging has become one of the most used diagnostic tools in the medical profession. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) technologies have become widely adopted because of their ability to capture the human body in a non-invasive manner. A volumetric dataset is a series of orthogonal 2D slices captured at a regular interval, typically along the axis of the body from the head to the feet. Volume rendering is a computer graphics technique that allows volumetric data to be visualized and manipulated as a single 3D object. Iso-surface rendering, image splatting, shear warp, texture slicing, and raycasting are volume rendering methods, each with associated advantages and disadvantages. Raycasting is widely regarded as the highest quality renderer of these methods. Originally, CT and MRI hardware was limited to providing a single 3D scan of the human body. The technology has improved to allow a set of scans capable of capturing anatomical movements like a beating heart. The capturing of anatomical data over time is referred to as functional imaging. Functional MRI (fMRI) is used to capture changes in the human body over time. While fMRI’s can be used to capture any anatomical data over time, one of the more common uses of fMRI is to capture brain activity. The fMRI scanning process is typically broken up into a time consuming high resolution anatomical scan and a series of quick low resolution scans capturing activity. The low resolution activity data is mapped onto the high resolution anatomical data to show changes over time. Academic research has advanced volume rendering and specifically fMRI volume rendering. Unfortunately, academic research is typically a one-off solution to a singular medical case or set of data, causing any advances to be problem specific as opposed to a general capability. Additionally, academic volume renderers are often designed to work on a specific device and operating system under controlled conditions. This prevents volume rendering from being used across the ever expanding number of different computing devices, such as desktops, laptops, immersive virtual reality systems, and mobile computers like phones or tablets. This research will investigate the feasibility of creating a generic software capability to perform real-time 4D volume rendering, via raycasting, on desktop, mobile, and immersive virtual reality platforms. Implementing a GPU-based 4D volume raycasting method for mobile devices will harness the power of the increasing number of mobile computational devices being used by medical professionals. Developing support for immersive virtual reality can enhance medical professionals’ interpretation of 3D physiology with the additional depth information provided by stereoscopic 3D. The results of this research will help expand the use of 4D volume rendering beyond the traditional desktop computer in the medical field. Developing the same 4D volume rendering capabilities across dissimilar platforms has many challenges. Each platform relies on their own coding languages, libraries, and hardware support. There are tradeoffs between using languages and libraries native to each platform and using a generic cross-platform system, such as a game engine. Native libraries will generally be more efficient during application run-time, but they require different coding implementations for each platform. The decision was made to use platform native languages and libraries in this research, whenever practical, in an attempt to achieve the best possible frame rates. 4D volume raycasting provides unique challenges independent of the platform. Specifically, fMRI data loading, volume animation, and multiple volume rendering. Additionally, real-time raycasting has never been successfully performed on a mobile device. Previous research relied on less computationally expensive methods, such as orthogonal texture slicing, to achieve real-time frame rates. These challenges will be addressed as the contributions of this research. The first contribution was exploring the feasibility of generic functional data input across desktop, mobile, and immersive virtual reality. To visualize 4D fMRI data it was necessary to build in the capability to read Neuroimaging Informatics Technology Initiative (NIfTI) files. The NIfTI format was designed to overcome limitations of 3D file formats like DICOM and store functional imagery with a single high-resolution anatomical scan and a set of low-resolution anatomical scans. Allowing input of the NIfTI binary data required creating custom C++ routines, as no object oriented APIs freely available for use existed. The NIfTI input code was built using C++ and the C++ Standard Library to be both light weight and cross-platform. Multi-volume rendering is another challenge of fMRI data visualization and a contribution of this work. fMRI data is typically broken into a single high-resolution anatomical volume and a series of low-resolution volumes that capture anatomical changes. Visualizing two volumes at the same time is known as multi-volume visualization. Therefore, the ability to correctly align and scale the volumes relative to each other was necessary. It was also necessary to develop a compositing method to combine data from both volumes into a single cohesive representation. Three prototype applications were built for the different platforms to test the feasibility of 4D volume raycasting. One each for desktop, mobile, and virtual reality. Although the backend implementations were required to be different between the three platforms, the raycasting functionality and features were identical. Therefore, the same fMRI dataset resulted in the same 3D visualization independent of the platform itself. Each platform uses the same NIfTI data loader and provides support for dataset coloring and windowing (tissue density manipulation). The fMRI data can be viewed changing over time by either animation through the time steps, like a movie, or using an interface slider to “scrub” through the different time steps of the data. The prototype applications data load times and frame rates were tested to determine if they achieved the real-time interaction goal. Real-time interaction was defined by achieving 10 frames per second (fps) or better, based on the work of Miller [1]. The desktop version was evaluated on a 2013 MacBook Pro running OS X 10.12 with a 2.6 GHz Intel Core i7 processor, 16 GB of RAM, and a NVIDIA GeForce GT 750M graphics card. The immersive application was tested in the C6 CAVE™, a 96 graphics node computer cluster comprised of NVIDIA Quadro 6000 graphics cards running Red Hat Enterprise Linux. The mobile application was evaluated on a 2016 9.7” iPad Pro running iOS 9.3.4. The iPad had a 64-bit Apple A9X dual core processor with 2 GB of built in memory. Two different fMRI brain activity datasets with different voxel resolutions were used as test datasets. Datasets were tested using both the 3D structural data, the 4D functional data, and a combination of the two. Frame rates for the desktop implementation were consistently above 10 fps, indicating that real-time 4D volume raycasting is possible on desktop hardware. The mobile and virtual reality platforms were able to perform real-time 3D volume raycasting consistently. This is a marked improvement for 3D mobile volume raycasting that was previously only able to achieve under one frame per second [2]. Both VR and mobile platforms were able to raycast the 4D only data at real-time frame rates, but did not consistently meet 10 fps when rendering both the 3D structural and 4D functional data simultaneously. However, 7 frames per second was the lowest frame rate recorded, indicating that hardware advances will allow consistent real-time raycasting of 4D fMRI data in the near future