Reconstructing vectorised photographic images

We address the problem of representing captured images in the continuous mathematical space more usually associated with certain forms of drawn ('vector') images. Such an image is resolution-independent so can be used as a master for varying resolution-specific formats. We briefly describe the main features of a vectorising codec for photographic images, whose significance is that drawing programs can access images and image components as first-class vector objects. This paper focuses on the problem of rendering from the isochromic contour form of a vectorised image and demonstrates a new fill algorithm which could also be used in drawing generally. The fill method is described in terms of level set diffusion equations for clarity. Finally we show that image warping is both simplified and enhanced in this form and that we can demonstrate real histogram equalisation with genuinely rectangular histograms

Pycortex: an interactive surface visualizer for fMRI.

Surface visualizations of fMRI provide a comprehensive view of cortical activity. However, surface visualizations are difficult to generate and most common visualization techniques rely on unnecessary interpolation which limits the fidelity of the resulting maps. Furthermore, it is difficult to understand the relationship between flattened cortical surfaces and the underlying 3D anatomy using tools available currently. To address these problems we have developed pycortex, a Python toolbox for interactive surface mapping and visualization. Pycortex exploits the power of modern graphics cards to sample volumetric data on a per-pixel basis, allowing dense and accurate mapping of the voxel grid across the surface. Anatomical and functional information can be projected onto the cortical surface. The surface can be inflated and flattened interactively, aiding interpretation of the correspondence between the anatomical surface and the flattened cortical sheet. The output of pycortex can be viewed using WebGL, a technology compatible with modern web browsers. This allows complex fMRI surface maps to be distributed broadly online without requiring installation of complex software

Icosatree Data Partitioning of Massive Geospatial Point Clouds with User-Selectable Entities and Surface Modeling

Massive point cloud data sets are currently being created and studied in academia, the private sector, and the military. Many previous attempts at rendering point clouds have allowed the user to visualize the data in a three-dimensional way but did not allow them to interact with the data and would require all data to be in memory at runtime. Recently, a few systems have emerged that deal with real-time rendering of massive point clouds with on-the-fly level of detail modification that handles out-of-core processing but these systems have their own limitations. With the size and scale of massive point cloud data coming from LiDAR (Light Detection and Ranging) systems, being able to visualize the data as well as interact and transform the data is needed. Previous work in out-of-core rendering showed that using Octrees and k-d trees can increase the availability of data as well as allow a user to visualize the information in a much more useful manner. However, viewing the data isn’t enough; applying work in context-aware selection and surface creation the visualization system would greatly benefit in usability and functionality. This paper explores a new data structure called an Icosatree, or icosahedral tree, that can be used to partition a point cloud dataset in the same fashion as an Octree is currently used. However, the Icosatree is made from triangular prism sub-cells which are tangential to the ellipsoidal surface used by Earth-based projected coordinate systems. In doing so, as new sub-cells are added to the rendering system, a much more uniform visualization emerges. Along the same lines, this paper applies portions of the aforementioned context-aware selection and surface creation algorithms to the resulting visualization such that a user may triangulate, prune and/or export portions of the point cloud dataset using an intuitive three dimensional interface and user-modifiable set of parameters. This allows the user to save items of interest for later analysis

Hierarchical volumetric object representations for digital fabrication workflows

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 111-114).Modern systems for computer-aided design and manufacturing (CAD/CAM) have a history dating back to drafting boards, early computers, and machine shops with specialized technicians for each stage in a manufacturing workflow. In recent years, personal-scale digital fabrication has challenged many of these workflows' build-in assumptions. A single individual may control the entire workflow, from design to manufacture; they will be using computers that are exponentially more powerful than those in the 1970s; and they may be using a wide variety of tools, machines, and processes. The variety of tools and machines leads to a combinatorial explosion of possible workflows. In addition, tools are based on boundary representations, which are fragile and can easily describe nonsensical objects. This thesis addresses these issues with a set of tools for end-to-end digital fabrication based on volumetric solid models. Workflows are modular, making it easy to add new machines, and a shared core of path-planning operations reduces system complexity. Replacing boundary representations with volumetric representations guarantees that models represent reasonable real-world solids. Adaptively sampled distance fields are used as a generic interchange format. Functional representations are used as a design representation, and we examine scaling behavior and efficient rendering. We present interactive design tools that use these representations as their geometry engine. Data from CT scans is also used to populate these distance fields, showing significant benefits in file size and resolution compared to meshes. Finally, these representations are used as inputs to a modular multimachine CAM workflow. Toolpath generation is implemented, characterized, and tested on a complex solid model. We conclude with a summary of results and recommendations for future research directions.by Matthew Keeter.S.M

Tuoris: A middleware for visualizing dynamic graphics in scalable resolution display environments

In the era of big data, large-scale information visualization has become an important challenge. Scalable resolution display environments (SRDEs) have emerged as a technological solution for building high-resolution display systems by tiling lower resolution screens. These systems bring serious advantages, including lower construction cost and better maintainability compared to other alternatives. However, they require specialized software but also purpose-built content to suit the inherently complex underlying systems. This creates several challenges when designing visualizations for big data, such that can be reused across several SRDEs of varying dimensions. This is not yet a common practice but is becoming increasingly popular among those who engage in collaborative visual analytics in data observatories. In this paper, we define three key requirements for systems suitable for such environments, point out limitations of existing frameworks, and introduce Tuoris, a novel open-source middleware for visualizing dynamic graphics in SRDEs. Tuoris manages the complexity of distributing and synchronizing the information among different components of the system, eliminating the need for purpose-built content. This makes it possible for users to seamlessly port existing graphical content developed using standard web technologies, and simplifies the process of developing advanced, dynamic and interactive web applications for large-scale information visualization. Tuoris is designed to work with Scalable Vector Graphics (SVG), reducing bandwidth consumption and achieving high frame rates in visualizations with dynamic animations. It scales independent of the display wall resolution and contrasts with other frameworks that transmit visual information as blocks of images

A tool for defining models of generic mobile machines

Tässä työssä esitellään mielivaltaisten liikkuvien työkoneiden nopeaan ja helppoon määrittelyyn tarkoitettu ohjelmisto. Käyttäjä määrittelee työkoneen yksinkertaisen, intuitiivisen 3D-käyttöliittymän avulla. Työkoneen määritelmän perusteella generoidaan sen kinemaattinen malli. Kinemaattisissa laskuissa käytetään uusimpia tutkimustuloksia erilaisten ajoneuvojen kinematiikasta. Generoiduilla kinemaattisilla malleilla voidaan simuloida mielivaltaisia konekonfiguraatioita erillisessä simulaattorimoduulissa, joka luotiin osana tätä työtä. Simulaattori tukee yleisimpiä teollisuudessa käytettyjä liikkuvia konetyyppejä, kuten automaisia, telaketjullisia, runkonivellettyjä tai passiivisesti yhdistettyjä koneita. Simuloidut ajoneuvot voivat myös yhdistellä eri konetyyppejä. Ohjelmistolla generoiduilla kinemaattisilla malleilla simuloidaan erilaisia tosimaailman ajoneuvokonfiguraatioita. Simulaatiotuloksia verrataan oikeista koneista saatuun dataan. Mallien havaitaan olevan tarkkoja ja sopivia erilaisiin tarkoituksiin, jotka vaativat ajoneuvon kinemaattisen mallin.In this thesis work, a software tool for quickly and easily defining a mobile vehicle is presented. Vehicles are defined through a simple, intuitive 3D graphical user interface. Based on the vehicle definition, a kinematic model is generated for the vehicle. The kinematics calculations use state-of-the-art knowledge on the kinematics of different vehicle types. The generated kinematic models can be used in a separate simulator module, also created for this thesis work, to simulate arbitrary vehicle configurations. Supported vehicle types include the most common mobile industrial vehicles, such as car-like, tracked, center-articulated or passively linked vehicles. Simulated vehicles can also be combinations of these types. Kinematic models generated with this software are tested against data sets gained from different real-world vehicle configurations. The models are found to be accurate and suitable for various purposes requiring a kinematic model of a vehicle

Design and implementation of 3D buildings integration for a Webgl-Based Virtual Globe: a case study of Valencian Cadastre and Fide Building Mode

Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.Since nowadays Web applications are increasingly providing plenty of creative and interesting services relying on new standards and more powerful computers, it becomes important to create similar applications, to process and visualize geographic data taking advantage of such groundings. In this context, it results interesting to develop new Web-based geo-processing based on a 3D data representation, exploiting the recent WebGL graphic specification from a client-side point of view. This research explains the novel way in which whole Valencian cadastre was analyzed, processed and finally represented into a WebGL-based virtual globe. These improvements provide end-users firstly, an optimization of computer graphics performance, by natively accessing to graphics instructions; and secondly a functional data management and representation for the present and forthcoming geo-processing Web-based platform

Actas do 12º Encontro Português de Computação Gráfica

Actas do 12º Encontro Portugês de Computação Gráfica, Porto, 8-10 de Outubro de 2003O Encontro Português de Computação Gráfica teve lugar nesse ano 2003, naquela que foi a sua 12ª edição, no ISEP – Instituto Superior de Engenharia do Porto, entre os 8 a 10 de Outubro. O 12º Encontro Português de Computação Gráfica (12EPCG) veio no seguimento de encontros anteriores realizados anualmente e reuniu investigadores, docentes e profissionais nacionais e estrangeiros, que realizam trabalho ou utilizam a Computação Gráfica, Realidade Virtual e Multimédia, assim como todas as suas áreas afins, no sentido de permitir a divulgação de projectos realizados ou em curso e fomentar a troca de experiências e a discussão de questões relacionadas com a Computação Gráfica em Portugal, entre as comunidades académica,industrial e a de utilizadores finais. Este é o livro de actas do 12EPCG.Fundação Ilídio PinhoFC