An Adaptive Cutaway with Volume Context Preservation

Knowledge expressiveness of scientific data is one of the most important visualization goals. However, current volume visualization systems require a lot of expertise from the final user. In this paper, we present a GPU-based ray casting interactive framework that computes two initial complementary camera locations and allows to select the focus interactively, on interesting structures keeping the volume’s context information with an adaptive cutaway technique. The adaptive cutaway surrounds the focused structure while preserving a depth immersive impression in the data set. Finally, we present a new brush widget to edit interactively the opening of the cutaway and to graduate the context in the final image.Peer ReviewedPostprint (published version

Modified Heritage

There are evidences of a rich history and heritage that centers around a once thriving African-American community in the late 1800’s and the early 1900’s. These thriving communities can also be called freedom colonies. These were post-emancipation settlements where African-Americans would intentionally begin to erect almost self-governing settlements with in-grown economics, education of the community, and a church that acted as an epicenter of refuge, initiative, and change. The project attempts to recognize these elements of empowerment within this context and zooms in even more so to the manifestation of black heritage in Washington County. How do we recognize the relationship between grounding the project in a particular vernacular context, yet instigate a slight deviance? How do we critically view the history of a black vernacular narrative arc both within Washington County and abroad, to both recognize it and modify it to contemporary interpretations? How do we negotiate how a project is fixed in time, yet understand the ascribed meanings and values may have changed, and will continue to change within the community? There are foundational truths to which this heritage has been built on with other layers of resilience following. This final study project provides a sketch to the possibilities of the intersection between a strong cultural discourse and the architectural environment. It attempts to delineate a past call, provide a present response, and initiate progress toward a modified future

A geometric discretization and a simple implementation for variational mesh generation and adaptation

We present a simple direct discretization for functionals used in the variational mesh generation and adaptation. Meshing functionals are discretized on simplicial meshes and the Jacobian matrix of the continuous coordinate transformation is approximated by the Jacobian matrices of affine mappings between elements. The advantage of this direct geometric discretization is that it preserves the basic geometric structure of the continuous functional, which is useful in preventing strong decoupling or loss of integral constraints satisfied by the functional. Moreover, the discretized functional is a function of the coordinates of mesh vertices and its derivatives have a simple analytical form, which allows a simple implementation of variational mesh generation and adaptation on computer. Since the variational mesh adaptation is the base for a number of adaptive moving mesh and mesh smoothing methods, the result in this work can be used to develop simple implementations of those methods. Numerical examples are given.Comment: Corrected and improved versio

Accountable artefacts: the case of the Carolan guitar

We explore how physical artefacts can be connected to digital records of where they have been, who they have encountered and what has happened to them, and how this can enhance their meaning and utility. We describe how a travelling technology probe in the form of an augmented acoustic guitar engaged users in a design conversation as it visited homes, studios, gigs, workshops and lessons, and how this revealed the diversity and utility of its digital record. We describe how this record was captured and flexibly mapped to the physical guitar and proxy artefacts. We contribute a conceptual framework for accountable artefacts that articulates how multiple and complex mappings between physical artefacts and their digital records may be created, appropriated, shared and interrogated to deliver accounts of provenance and use as well as methodological reflections on technology probes

Model-Based Visualization for Intervention Planning

Computer support for intervention planning is often a two-stage process: In a first stage, the relevant segmentation target structures are identified and delineated. In a second stage, image analysis results are employed for the actual planning process. In the first stage, model-based segmentation techniques are often used to reduce the interaction effort and increase the reproducibility. There is a similar argument to employ model-based techniques for the visualization as well. With increasingly more visualization options, users have many parameters to adjust in order to generate expressive visualizations. Surface models may be smoothed with a variety of techniques and parameters. Surface visualization and illustrative rendering techniques are controlled by a large set of additional parameters. Although interactive 3d visualizations should be flexible and support individual planning tasks, appropriate selection of visualization techniques and presets for their parameters is needed. In this chapter, we discuss this kind of visualization support. We refer to model-based visualization to denote the selection and parameterization of visualization techniques based on \u27a priori knowledge concerning visual perception, shapes of anatomical objects and intervention planning tasks

Peak Oil and Transition: The Making of a Documentary Video

Many scientists and academics have raised serious concerns regarding the depletion of fossil fuels—especially the peaking of oil production—and its impact upon society. According to these researchers, oil for transportation and production will soon become expensive and scarce, and known alternative sources of energy will be insufficient to make up the difference within the required time frame. Therefore, world civilization (and the United States in particular) will soon undergo a crisis in energy supply that will have significant impacts on the structure of community life, economic wellbeing, political organization, and individual lifestyles. One response to these threats is to attempt to develop mitigation strategies for communities that involve strong conservation measures and relocalization of crucial necessities like food and energy production. During the past decade, many Sustainability and Transition organizations have been formed by citizen activists to educate their citizens about the challenges of peak oil, and to evolve approaches to overcome them. The primary purpose of this dissertation is, through a documentary video production, to examine the likely impacts of peak oil and to investigate strategies for promoting community resilience, focusing particularly on the emergence of v Sustainability and Transition groups in northern California. The method of the inquiry is participative action research, employing interviews with scholars and community leaders on the subject of peak oil and strategies for community adaptation. The primary components of this documentary are video interviews and supporting footage, with the objectives of explaining the concept of peak oil; demonstrating why alternative technologies may prove insufficient to replace fossil fuels; examining the potential economic, social and psychological impacts of energy shortages; and demonstrating the process of activist organization in pursuit of strategies and tactics to promote community resilience. In particular, this research focuses on representatives of organizations that study the impacts of peak oil, such as the Post Carbon Institute and Post Peak Living; and Transition and Sustainability initiatives in the northern California counties of Marin, Sonoma, and Mendocino

PRESERVATION FOR FUTURE GENERATIONS: DIGITAL TECHNOLOGIES, DIGITALIZATION, AND EXPERIMENTS WITH CONSUMERS AS PRODUCERS OF INDUSTRIAL HERITAGE DOCUMENTATION

As digital documentation and recording technologies have evolved, so has the perception that they are segregated and intended primarily for use in either engineering/scientific or amateur/consumer applications. In contrast to this notion, the three-dimensionality afforded by these technologies differs only when considering them in the order of priorities; laser scanners and related image acquisition technologies document and visualize while inversely, consumer cameras visualize and document. This broad field of digital acquisition technologies has evolved into a heterogeneity of tools that all capture aspects of the physical world with a line drawn between them becoming blurred. Within this evolution, these tools are becoming less expensive, easier to use, and depending upon the application, can be operated successfully by individuals having modest or semi-professional skills. The proliferation of digital documentation technologies, the ease of their use, and the ability to share visual data on the internet allow us to examine the inclusion of digital documentation into the preservation management of historic industrial resource, pushing heritage to the digitalized culture

Enhanced perception in volume visualization

Due to the nature of scientic data sets, the generation of convenient visualizations may be a difficult task, but crucial to correctly convey the relevant information of the data. When working with complex volume models, such as the anatomical ones, it is important to provide accurate representations, since a misinterpretation can lead to serious mistakes while diagnosing a disease or planning surgery. In these cases, enhancing the perception of the features of interest usually helps to properly understand the data. Throughout years, researchers have focused on different methods to improve the visualization of volume data sets. For instance, the definition of good transfer functions is a key issue in Volume Visualization, since transfer functions determine how materials are classified. Other approaches are based on simulating realistic illumination models to enhance the spatial perception, or using illustrative effects to provide the level of abstraction needed to correctly interpret the data. This thesis contributes with new approaches to enhance the visual and spatial perception in Volume Visualization. Thanks to the new computing capabilities of modern graphics hardware, the proposed algorithms are capable of modifying the illumination model and simulating illustrative motifs in real time. In order to enhance local details, which are useful to better perceive the shape and the surfaces of the volume, our first contribution is an algorithm that employs a common sharpening operator to modify the lighting applied. As a result, the overall contrast of the visualization is enhanced by brightening the salient features and darkening the deeper regions of the volume model. The enhancement of depth perception in Direct Volume Rendering is also covered in the thesis. To do this, we propose two algorithms to simulate ambient occlusion: a screen-space technique based on using depth information to estimate the amount of light occluded, and a view-independent method that uses the density values of the data set to estimate the occlusion. Additionally, depth perception is also enhanced by adding halos around the structures of interest. Maximum Intensity Projection images provide a good understanding of the high intensity features of the data, but lack any contextual information. In order to enhance the depth perception in such a case, we present a novel technique based on changing how intensity is accumulated. Furthermore, the perception of the spatial arrangement of the displayed structures is also enhanced by adding certain colour cues. The last contribution is a new manipulation tool designed for adding contextual information when cutting the volume. Based on traditional illustrative effects, this method allows the user to directly extrude structures from the cross-section of the cut. As a result, the clipped structures are displayed at different heights, preserving the information needed to correctly perceive them.Debido a la naturaleza de los datos científicos, visualizarlos correctamente puede ser una tarea complicada, pero crucial para interpretarlos de forma adecuada. Cuando se trabaja con modelos de volumen complejos, como es el caso de los modelos anatómicos, es importante generar imágenes precisas, ya que una mala interpretación de las mismas puede producir errores graves en el diagnóstico de enfermedades o en la planificación de operaciones quirúrgicas. En estos casos, mejorar la percepción de las zonas de interés, facilita la comprensión de la información inherente a los datos. Durante décadas, los investigadores se han centrado en el desarrollo de técnicas para mejorar la visualización de datos volumétricos. Por ejemplo, los métodos que permiten definir buenas funciones de transferencia son clave, ya que éstas determinan cómo se clasifican los materiales. Otros ejemplos son las técnicas que simulan modelos de iluminación realista, que permiten percibir mejor la distribución espacial de los elementos del volumen, o bien los que imitan efectos ilustrativos, que proporcionan el nivel de abstracción necesario para interpretar correctamente los datos. El trabajo presentado en esta tesis se centra en mejorar la percepción de los elementos del volumen, ya sea modificando el modelo de iluminación aplicado en la visualización, o simulando efectos ilustrativos. Aprovechando la capacidad de cálculo de los nuevos procesadores gráficos, se describen un conjunto de algoritmos que permiten obtener los resultados en tiempo real. Para mejorar la percepción de detalles locales, proponemos modificar el modelo de iluminación utilizando una conocida herramienta de procesado de imágenes (unsharp masking). Iluminando aquellos detalles que sobresalen de las superficies y oscureciendo las zonas profundas, se mejora el contraste local de la imagen, con lo que se consigue realzar los detalles de superficie. También se presentan diferentes técnicas para mejorar la percepción de la profundidad en Direct Volume Rendering. Concretamente, se propone modificar la iluminación teniendo en cuenta la oclusión ambiente de dos maneras diferentes: la primera utiliza los valores de profundidad en espacio imagen para calcular el factor de oclusión del entorno de cada pixel, mientras que la segunda utiliza los valores de densidad del volumen para aproximar dicha oclusión en cada vóxel. Además de estas dos técnicas, también se propone mejorar la percepción espacial y de la profundidad de ciertas estructuras mediante la generación de halos. La técnica conocida como Maximum Intensity Projection (MIP) permite visualizar los elementos de mayor intensidad del volumen, pero no aporta ningún tipo de información contextual. Para mejorar la percepción de la profundidad, proponemos una nueva técnica basada en cambiar la forma en la que se acumula la intensidad en MIP. También se describe un esquema de color para mejorar la percepción espacial de los elementos visualizados. La última contribución de la tesis es una herramienta de manipulación directa de los datos, que permite preservar la información contextual cuando se realizan cortes en el modelo de volumen. Basada en técnicas ilustrativas tradicionales, esta técnica permite al usuario estirar las estructuras visibles en las secciones de los cortes. Como resultado, las estructuras de interés se visualizan a diferentes alturas sobre la sección, lo que permite al observador percibirlas correctamente