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Now showing 1 - 6 of 6
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    A Moving Least Squares Method for Implant Model Deformation in Computer Aided Orthopedic Surgery for Fractures of Lower Extremities
    (The Eurographics Association, 2021) Ramírez, Esmitt; Coto, Ernesto; Silva, F. and Gutierrez, D. and Rodríguez, J. and Figueiredo, M.
    Preoperative planning is an essential step before performing any surgical procedure. Computer Aided Orthopedic Surgery (CAOS) systems are extensively used for the planning of surgeries for fractures of lower extremities. These systems are input an X-Ray image and the planning can be digitally overlaid onto the image. The planning includes reassembling the fractured bone and possibly adding implants to reduce the fracture. In many cases, the implant does not fit perfectly in the patient's anatomy and it must be bended to adjust the implant to the bone. This paper presents a new method for the deformation of implants in CAOS systems, based on the Moving Least Squares (MLS) method for 2D images. Several improvements over the original MLS method are introduced to achieve visual results similar to the real procedure and make the deformation process easier and simpler for the surgeon. The improvements are explained in detail and all parameter values are provided. Over 100 clinical surgeries have been already planned successfully using a CAOS system that employs the proposed technique.
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    A Digital Approach for the Study of Roman Signacula From Syracuse, Sicily
    (The Eurographics Association, 2017) Tanasi, Davide; Milotta, Filippo L. M.; Gradante, Ilenia; Stanco, Filippo; Kaplan, Howard; Andrea Giachetti and Paolo Pingi and Filippo Stanco
    In the last decade the epigraphists have grown a new interest in signacula, a class of artifacts for a long time neglected. This has brought numerous contributions devoted to the different regional contexts, along with reflections on methodological questions, not to mention the momentum towards the digitizing of a corpus which counts at least 3,500 pieces, confirming the great potential of these artifacts in providing information related not only to the economy and to the administration of the ''res'', both in public and private sphere, but also about the profile of the signacula holders. In this scenario, a specific research question has been inspired by the Sicilian seals - about 60 signacula and a dozen impressions left by seals on mortar in burial contexts: it is possible to identify unequivocally a signaculum through its impression? Given for granted that the use of 3D documentation will bring along effective results in terms of improved readability of signacula and seals, the aim of this contribute is to establish a protocol for a semi-automatic matching between 3D models of seals and 3D models of impressions. As part of a preliminary scanning campaign of Late Roman impressions on mortars and metal seals from the catacombs of Syracuse, two bronze metal seals were digitized with a NextEngine 3D triangulation laser scanner and subsequently 3D printed with liquid resin with a Formlabs Form 2 SLA high resolution printer. The casts obtained, were experimentally used to create a set of impressions on mortar using different degrees and angles of pressure, in order to create similar but still different stamps. During the next step, the impressions were 3D scanned and used as ground truth for the outlined semi-automatic procedure of matching with the seals. In MeshLab environment, the 3d models of seals and impressions were manually aligned and then the distance between two sets of 3D points was measured using the filter Hausdorff distance in order to validate a matching. This successful exercise could open the way to the proposal of creating a virtual edition of signacula with 3D models metadata. Furthermore, a research agenda may include the design of a machine learning algorithm for matching of 3D meshes.
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    The Social Picture: Advanced Image Analysis Applications
    (The Eurographics Association, 2017) Milotta, Filippo L. M.; Bellocchi, Michele; Battiato, Sebastiano; Andrea Giachetti and Paolo Pingi and Filippo Stanco
    In The Social Picture (TSP) an huge amount of crowdsourced social images can be collected and explored. We distinguish three main kind of events: public, private and cultural heritage related ones. The framework embeds a number of advanced Computer Vision algorithms, able to capture the visual content of images and organize them in a semantic way. In this paper we employ VisualSFM (VSFM) to add new features in TSP through the computation of a 3D sparse reconstruction of a collection within TSP. VisualSFM creates a N-View Match (NVM) file as output. Starting from this NVM file, which characterizes the 3D sparse reconstruction, we are able to build two important relationships: the one between cameras and points and the one between cameras themselves. Using these relationships, we implemented two advanced Image Analysis applications. In the first one, we consider the cameras as nodes in a fully connected graph in which the edges weights are equal to the number of matches between cameras. The spanning tree of this graph is used to explore images in a meaningful way, obtaining a scene summarization. In the second application, we define three kinds of density maps with relation to image features: density map, weighted-density map and social-weighted-density map. Results of a test conducted on a collection from TSP is shown.
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    gVirtualXRay: Virtual X-Ray Imaging Library on GPU
    (The Eurographics Association, 2017) Sujar, Aaron; Meuleman, Andreas; Villard, Pierre-Frederic; García, Marcos; Vidal, Franck; Tao Ruan Wan and Franck Vidal
    We present an Open-source library called gVirtualXRay to simulate realistic X-ray images in realtime. It implements the attenuation law (also called Beer-Lambert) on GPU. It takes into account the polychromatism of the beam spectra as well as the finite size of X-ray tubes. The library is written in C++ using modern OpenGL. It is fully portable and works on most common desktop/laptop computers. It has been tested on MS Windows, Linux, and Mac OS X. It supports a wide range of windowing solutions, such as FLTK, GLUT, GLFW3, Qt4, and Qt5. The library also offers realistic visual rendering of anatomical structures, including bones, liver, diaphragm and lungs. The accuracy of the X-ray images produced by gVirtualXRay's implementation has been validated using Geant4, a well established state-of-the-art Monte Carlo simulation toolkit developed by CERN. gVirtualXRay can be used in a wide range of applications where fast and accurate X-ray simulations from polygon meshes are needed, e.g. medical simulators for training purposes, simulation of tomography data acquisition with patient motion to include artefacts in reconstructed CT images, and deformable registration. Our application example package includes real-time respiration and X-ray simulation, CT acquisition and reconstruction, and iso-surfacing of implicit functions using Marching Cubes.
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    3D GIS Based on WebGL for the Management of Underground Utilities
    (The Eurographics Association, 2017) Jurado, Juan Manuel; Ortega, Lidia; Feito, Francisco R.; Fco. Javier Melero and Nuria Pelechano
    This work summarizes a web application related to a research project about underground infrastructures. The aim is to visualize, analyse and manage all underground layers inside 3D urban environments. This is possible using WebGL to develop a web application which may be used from mobile devices. The study of terrain relief to calculate the depth of these infrestructures, the conversion of 2D data to 3D models, the definition of a spatial database and the use of virtual reality to visualize the resulting 3D scene make of this application a useful tool for utility companies dealing with underground infrastructures.
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    Neural Data Exploration with Force Feedback
    (The Eurographics Association, 2021) Raya, Laura; Otaduy, Miguel A.; García, Marcos; Silva, F. and Gutierrez, D. and Rodríguez, J. and Figueiredo, M.
    The behavior of the brain depends to a large extend on its neural structure. Therefore, understanding this neural topology is a high-priority research line for neurobiologists. Due to complexity of the brain's neural structure, visual representations look tangled, and extracting knowledge from them is a difficult task. In this work, we propose the use of multimodal interfaces to enhance neurobiologists' understanding of neural data. Our system is based on four pillars: a stereo rendering module, a camera control system, a visual aid unit, and a haptically constrained navigation tool. We observe that haptically aided navigation helps neurobiologists analyze the brain's topology. Our system uses stylus-based haptic devices with two purposes: they provide a natural interface to deal with 3D data (controlling camera motion) and they constrain the user's motion. The system was built trying to keep user interactions as intuitive as possible.