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Behr, Johannes; Blach, Roland; Bockholt, Ulrich; Harth, Andreas; Hoffmann, Hilko; Huber, Manuel; Käfer, Tobias; Keppmann, Felix Leif; Pankratz, Frieder; Rubinstein, Dmitri; Schubotz, René; Vogelgesang, Christian; Voss, Gerrit

ARVIDA-Referenzarchitektur

2017

Web-basierte Anwendungen Virtueller Techniken: Das ARVIDA-Projekt - Dienste-basierte Software-Architektur und Anwendungsszenarien für die Industrie

Die ARVIDA-Referenzarchitektur ist ein zentrales Element und Ergebnis des ARVIDA- Projektes. Sie ermöglicht es, mit etablierten Technologien und Konzepten aus dem Web-Umfeld heterogene VT-Systemlandschaften in integrierten, sehr weitgehend plattformunabhängigen VT-Anwendungen effizient zu nutzen. Die Referenzarchitektur nutzt und adaptiert das Prinzip der RESTful-Web-Services sowie die darauf aufbauenden Linked-Data Konzepte, um interoperable, leicht erweiterbare und modulare VTAnwendungen zu bauen. Die nachfolgenden Abschnitte beschreiben die Grundprinzipien und spezifischen Erweiterungen im Detail.

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Ming, Qi; Erdt, Marius; Kan, Chen; Lee, Eugene; Voss, Gerrit; Müller-Wittig, Wolfgang K.

InfoView3D: A Solution Showing Educational Model on Multi-Touch Surfaces

2015

Eurographics 2015. Education Papers

Annual Conference of the European Association for Computer Graphics (Eurographics) <36, 2015, Zürich, Switzerland>

In this paper, we present a solution for educational presentation which can integrate images, documents, videos, and especially 3D models in a tree based structure. The solution is based on HTML5 and JavaScript, using SVG and X3D techniques and interacting with multi-touch events, therefore supporting multi-touch surfaces that can run a fully-functional browser. In practice, our solution is used for demonstrations both on tablet PCs and a multi-touch video wall.

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Behr, Johannes; Mouton, Christophe; Parfouru, Samuel; Champeau, Julien; Jeulin, Clotilde; Thöner, Maik; Stein, Christian; Schmitt, Michael; Limper, Max; Sousa, Miguel de; Franke, Tobias; Voss, Gerrit

webVis/instant3DHub - Visual Computing as a Service Infrastructure to Deliver Adaptive, Secure and Scalable User Centric Data Visualisation

2015

Proceedings Web3D 2015

International Conference on 3D Web Technology (WEB3D) <20, 2015, Heraklion, Crete, Greece>

This paper presents the webVis / instant3DHub platform, which combines a novel Web-Components based framework and a Visual Computing as a Service infrastructure to deliver an interactive 3D data visualisation solution. The system focuses on minimising resource consumption, while maximising the end-user experience. It utilises an adaptive and automated combination of client, server and hybrid visualisation techniques, while orchestrating transmission, caching and rendering services to deliver structural and semantically complex data sets on any device class and network architecture. The API and Web Component framework allow the application developer to compose and manipulate complex data setups with a simple set of commands inside the browser, without requiring knowledge about the underlying service infrastructure, interfaces and the fully automated processes. This results in a new class of interactive applications, built around a canvas for real-time visualisation of massive data sets.

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Schwenk, Karsten; Voss, Gerrit; Behr, Johannes; Jung, Yvonne; Limper, Max; Herzig, Pasquale; Kuijper, Arjan

Extending a Distributed Virtual Reality System with Exchangeable Rendering Back-Ends

2013

The Visual Computer

We present an approach to integrate multiple rendering back-ends under a common application layer for distributed systems. The primary goal was to find a practical and nonintrusive way to use potentially very different renderers in heterogeneous computing environments without impairing their strengths and without burdening the back-ends or the application with details of the cluster environment. Our approach is based on a mediator layer that handles multithreading, clustering, and the synchronization between the application's and the back-end's scene. We analyze the proposed approach with an implementation for a state-of-the- art distributed VR/AR system. In particular, we present two case studies and an example application.

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Schwenk, Karsten; Voss, Gerrit; Behr, Johannes

A System Architecture for Flexible Rendering Back-ends in Distributed Virtual Reality Applications

2012

2012 International Conference on Cyberworlds. Proceedings

International Conference on Cyberworlds (CW) <11, 2012, Darmstadt, Germany>

We describe an approach to integrate multiple rendering back-ends under a common application layer for distributed systems. The primary goal was to find a practical and non-intrusive way to use potentially very different rendering back-ends in heterogeneous computing environments without impairing their strengths and without burdening the backends or the application with details of the cluster environment. Our approach is based on a mediator layer that can be plugged into the OpenSG infrastructure. This design allows us to elegantly extent OpenSG's low-level multithreading and clustering capabilities to our system. It also allows us to sync incremental changes very efficiently. We demonstrate results and problems with two case studies.

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Schwenk, Karsten; Jung, Yvonne; Voss, Gerrit; Sturm, Timo; Behr, Johannes

CommonSurfaceShader Revisited: Improvements and Experiences

2012

Proceedings Web3D 2012

International Conference on 3D Web Technology (WEB3D) <17, 2012, Los Angeles, CA, USA>

We present an improved version of the CommonSurfaceShader node, a modern declarative surface shader for X3D. The new version is better suited for physically-based rendering, has support for anisotropic surfaces, and overcomes some of the limitations the original design had for layered materials. We also present a general discussion of how the node performed in practice.

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Lancelle, Marcel; Voss, Gerrit; Fellner, Dieter W.

Fast Motion Rendering for Single-Chip Stereo DLP Projectors

2012

Virtual Environments 2012

Joint Virtual Reality Conference (JVRC) <4, 2012, Madrid, Spain>

Single-chip color DLP projectors show the red, green and blue components one after another. When the gaze moves relative to the displayed pixels, color fringes are perceived. In order to reduce these artefacts, many devices show the same input image twice at the double rate, i.e. a 60Hz source image is displayed with 120Hz. Consumer stereo projectors usually work with time interlaced stereo, allowing to address each of these two images individually. We use this so called 3D mode for mono image display of fast moving objects. Additionally, we generate a separate image for each individual color, taking the display time offset of each color component into account. With these 360 images per second we can strongly reduce ghosting, color fringes and jitter artefacts on fast moving objects tracked by the eye, resulting in sharp objects with smooth motion. Real-time image generation at such a high frame rate can only be achieved for simple scenes or may only be possible by severely reducing quality. We show how to modify a motion blur post processing shader to render only 60frames=second and efficiently generate good approximations of the missing frames.

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Liu, Weiguo; Schmidt, Bertil; Liu, Yongchao; Voss, Gerrit; Müller-Wittig, Wolfgang K.

Mapping of BLASTP Algorithm onto GPU Clusters

2011

International Conference on Parallel and Distributed Systems

International Conference on Parallel and Distributed Systems (ICPADS) <17, 2011, Tainan, Taiwan>

Searching protein sequence database is a fundamental and often repeated task in computational biology and bioinformatics. However, the high computational cost and long runtime of many database scanning algorithms on sequential architectures heavily restrict their applications for large-scale protein databases, such as GenBank. The continuing exponential growth of sequence databases and the high rate of newly generated queries further deteriorate the situation and establish a strong requirement for time-efficient scalable database searching algorithms. In this paper, we demonstrate how GPU clusters, powered by the Compute Unified Device Architecture (CUDA), OpenMP, and MPI parallel programming models can be used as an efficient computational platform to accelerate the popular BLASTP algorithm. Compared to GPU-BLAST 1.0-2.2.24, our implementation achieves speedups up to 1.6 on a single GPU and up to 6.6 on the 6 GPUs of a Tesla S1060 quad- GPU computing system. The source code is available at: http://sites.google.com/site/liuweiguohome/mpicuda-blastp

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Liu, Weiguo; Schmidt, Bertil; Voss, Gerrit; Müller-Wittig, Wolfgang K.

Accelerating Molecular Dynamics Simulations Using Graphics Processing Units with CUDA

2008

Computer Physics Communications

Molecular dynamics is an important computational tool to simulate and understand biochemical processes at the atomic level. However, accurate simulation of processes such as protein folding requires a large number of both atoms and time steps. This in turn leads to huge runtime requirements. Hence, finding fast solutions is of highest importance to research. In this paper we present a new approach to accelerate molecular dynamics simulations with inexpensive commodity graphics hardware. To derive an efficient mapping onto this type of computer architecture, we have used the new Compute Unified Device Architecture programming interface to implement a new parallel algorithm. Our experimental results show that the graphics card based approach allows speedups of up to factor nineteen compared to the corresponding sequential implementation.

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Müller-Wittig, Wolfgang K.; Voss, Gerrit

Challenges for Modern Scene-Graph Systems

2007

5th Italian Chapter Conference

Eurographics Italian Chapter Conference <5, 2007, Trento, Italy>

Current scenegraph systems, especially systems used to build general purpose virtual reality systems, are trailing game engines and similar specialized systems in terms of the adaption of new renderingmethods like the different real-time shadow algorithms. This paper analysis the fundamental OpenGL state abstraction layers present in current scenegraph systems with respect to their influence on the adaption of new and complex rendering algorithms.

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Reiners, Dirk; Voss, Gerrit

Climbing Longs Peak

2007

IEEE Computer Graphics and Applications

One of the bedrock components of interactive graphics applications is getting an overhaul-the first one in 14 years. And it's not just a small face-lift; it's a fundamental overhaul that might impact the way interactive graphics applications are written for a long time to come. That component is OpenGL. From the beginning, one of OpenGL's most defining characteristics has been an emphasis on backward compatibility. Code written for OpenGL 1.0 will still compile and run today, exactly as it did 14 years ago, although hopefully a lot faster. The OpenGL Architecture Review Board (ARB), the custodian of OpenGL's state and development, has been rigorous about keeping the backward compatibility intact. Now, for the first time, that's changing. And by Siggraph 2007, the first version of the new OpenGL specifications will be made public. The changes are significant, and people who haven't been closely following OpenGL's development won't recognize much. To understand what motivated this drastic change after more than a decade of stability, let's look at the history and motivations behind OpenGL.

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Müller-Wittig, Wolfgang K.; Zhu, Chao; Voss, Gerrit

Cultural Heritage as Digital Experience: A Singaporean Perspective

2007

HCI International 2007. Proceedings and Posters [DVD-ROM]

International Conference on Virtual Reality (ICVR) <2, 2007, Beijing, China>

Interactive 3D computer graphics technology is now extremely popular, seen in the increasing interest in and use of 3D digitization of cultural heritage contents. This paper introduces a digital interactive cultural heritage system which embeds Virtual-Reality (VR) technology within the Peranakan culture, the Peranakan culture being a Singaporean unique ethnic culture. A prototype has undergone the full developmental process of being implemented, tested, and evaluated. This paper will also discuss the results of the usability test.

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Liu, Weiguo; Schmidt, Bertil; Voss, Gerrit; Müller-Wittig, Wolfgang K.

Streaming Algorithms for Biological Sequence Alignment on GPUs

2007

IEEE Transactions on Parallel and Distributed Systems

Sequence alignment is a common and often repeated task in molecular biology. Typical alignment operations consist of finding similarities between a pair of sequences (pairwise sequence alignment) or a family of sequences (multiple sequence alignment). The need for speeding up this treatment comes from the rapid growth rate of biological sequence databases: Every year their size increases by a factor of 1.5 to 2. In this paper, we present a new approach to high-performance biological sequence alignment based on commodity PC graphics hardware. Using modern graphics processing units (GPUs) for high-performance computing is facilitated by their enhanced programmability and motivated by their attractive price/performance ratio and incredible growth in speed. To derive an efficient mapping onto this type of architecture, we have reformulated dynamic-programming-based alignment algorithms as streaming algorithms in terms of computer graphics primitives. Our experimental results show that the GPU-based approach allows speedups of more than one order of magnitude with respect to optimized CPU implementations.

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Liu, Weiguo; Schmidt, Bertil; Voss, Gerrit; Schröder, Andre; Müller-Wittig, Wolfgang K.

Bio-Sequence Database Scanning on a GPU

2006

Proceedings of the 20th International Parallel and Distributed Processing Symposium

IEEE International Parallel and Distributed Processing Symposium (IPDPS) <20, 2006, Rhodes Island, Greece>

Protein sequences with unknown functionality are often compared to a set of known sequences to detect functional similarities. Efficient dynamic programming algorithms exist for this problem, however current solutions still require significant scan times. These scan time requirements are likely to become even more severe due to the rapid growth in the size of these databases. In this paper, we present a new approach to bio-sequence database scanning using computer graphics hardware to gain high performance at low cost. To derive an efficient mapping onto this type of architecture, we have reformulated the Smith- Waterman dynamic programming algorithm in terms of computer graphics primitives. Our OpenGL implementation achieves a speedup of approximately sixteen on a high-end graphics card over available straightforward and optimized CPU Smith-Waterman implementations.

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Liu, Weiguo; Schmidt, Bertil; Voss, Gerrit; Müller-Wittig, Wolfgang K.

GPU-ClustalW: Using Graphics Hardware to Accelerate Multiple Sequence Alignment

2006

High Performance Computing

International Conference on High-Performance Computing (HiPC) <13, 2006, Bangalore, India>

Molecular Biologists frequently compute multiple sequence alignments (MSAs) to identify similar regions in protein families. However, aligning hundreds of sequences by popular MSA tools such as ClustalW requires several hours on sequential computers. Due to the rapid growth of biological sequence databases biologists have to compute MSAs in a far shorter time. In this paper we present a new approach to reduce this runtime using graphics processing units (GPUs). To derive an effient mapping onto this type of architecture, we have reformulated the computationally most expensive part of ClustalW in terms of computer graphics primitives. This results in a high-speed implementation with significant runtime savings on a commodity graphics card.

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Voss, Gerrit; Reiners, Dirk

Towards a Flexible Back-End for Scenegraph-Based Rendering Systems

2006

Proceedings GRAPHITE 2006

International Conference on Computer Graphics and Interactive Techniques in Australasia and South East Asia (GRAPHITE) <4, 2006, Kuala Lumpur, Malaysia>

Current scenegraph systems, especially systems used to build general purpose virtual reality systems, are trailing game engines and similar specialized systems in terms of the adaption of new rendering methods like the different real-time shadow algorithms. This paper analysis the fundamental OpenGL state abstraction layers present in current scenegraph systems with respect to their influence on the adaption of new and complex rendering algorithms. Several shortcomings are identified and new approaches to overcome the current restrictions and limitations are proposed.

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Voss, Gerrit; Müller-Wittig, Wolfgang K.; Schmidt, Bertil; Schröder, Andre

Using Graphics Hardware to Accelerate Biological Sequence Database Scanning

2005

TENCON 2005

IEEE International Region 10 Conferences (TENCON) <2005, Melbourne, Australia>

Sequence alignment is a common and often repeated task in molecular biology. The need for speeding up this treatment comes from the rapid growth rate of biological sequence databases. In this paper we present a new approach to high performance biological sequence database scanning on graphics processing units. Using modern graphics processing units for high performance computing is facilitated by their enhanced programmability and motivated by their attractive price/performance ratio and incredible growth in speed. To derive an efficient mapping onto this type of architecture, we have reformulated the Smith-Waterman dynamic programming algorithm in terms of computer graphics primitives. This results in an implementation with significant runtime savings on two standard off-the-shelf computer graphics cards. To our knowledge this is the first reported mapping of biological sequence alignment onto a graphics processing unit.

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Roth, Marcus; Voss, Gerrit; Reiners, Dirk

Multi-threading and Clustering for Scene Graph Systems

2004

Computers & Graphics

The support for multi-threaded applications in current scene graphs is very limited, if it is supported at all. This work presents an approach for a very general multi-threading framework that allows total separation of threads without total replication of data. It also supports extensions to clusters, both for sort-first and sort-last rendering configurations. The described concepts have been implemented in the OpenSG scene graph and are widely and successfully used.

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Bockholt, Ulrich; Bisler, Alexander; Becker, Mario; Müller-Wittig, Wolfgang K.; Voss, Gerrit

Augmented Reality for Enhancement of Endoscopic Interventions

2003

IEEE Virtual Reality 2003 Conference. Proceedings

IEEE Virtual Reality (VR) <10, 2003, Los Angeles, CA, USA>

Computer assisted operation planning systems win more and more recognition in the field of surgery. These systems offer new possibilities to prepare an intervention with the goal to shorten the expansive time in the operation room required for the intervention. The safest and most effective surgical approach should be selected. But often, it is difficult to transfer the output of the planning system to the intra-operative situation and so to consider the planning results in the real intervention. At the Fraunhofer Institute for Computer Graphics (IGD) in Darmstadt and the Centre for Advanced Media Technology (CAMTech) in Singapore, methods are developed to bridge the gap between the external planning session and the intra-operative case: Augmented Reality (AR) techniques are used to overlap preoperative scanned image data as well as results of the planning session to the operation field.

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Voss, Gerrit; Behr, Johannes; Reiners, Dirk; Roth, Marcus

A Multi-thread Safe Foundation for Scene Graphs and its Extension to Clusters

2002

Fourth Eurographics Workshop on Parallel Graphics and Visualisation 2002. Proceedings

Eurographics Workshop on Parallel Graphics and Visualisation (EGPGV) <4, 2002, Blaubeuren, Germany>

One of the main shortcomings of current scene graphs is their inability to support multi-thread safe data structures. This work describes the general framework used by the OpenSG scene graph system to enable multiple concurrent threads to independently manipulate the scene graph without interfering with each other. Furthermore the extensions of the presented mechanisms needed to support cluster systems are discussed.

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Müller-Wittig, Wolfgang K.; Bockholt, Ulrich; Voss, Gerrit; Börner, Martin

A New Approach to Combine Visualization and Simulation for Preoperative Planning of Pedicle Screw Insertion

2002

Computer Assisted Orthopaedic Surgery. Proceedings 2002

Annual Meeting of the International Society for Computer Assisted Orthopaedic Surgery (CAOS) <2, 2002, Santa Fe, NM, USA>

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Müller-Wittig, Wolfgang K.; Becker, Mario; Bockholt, Ulrich; Voss, Gerrit

Advanced Simulation Environment for Minimally Invasive Procedures in Gynecology

2002

ITEC 2002. Europe's Training, Education and Simulation Conference Proceedings. CD-ROM

International Training and Education Conference & Exhibition (ITEC) <13, 2002, Lille, France>

Rapid development of medical field, expanding knowledge base and new technologies require continuing medical education to achieve life long learning and to keep the surgeons up to date. Consequently, specific training is necessary to guarantee qualification of the surgeons. To overcome the current drawbacks of traditional training systems (on-the-job training, plastic models etc.) for laparoscopy/hysteroscopy an intelligent adaptable training environment has been realized using Virtual Reality (VR), Multimedia (MM) technology, and Intelligent Tutoring Systems (ITS).

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Müller-Wittig, Wolfgang K.; Becker, Mario; Elias, Thomas; Bockholt, Ulrich; Voss, Gerrit

Advanced Training Environment for Gynecologic Endoscopy

2002

Computer Assisted Radiology and Surgery 2002. Proceedings

Computer Assisted Radiology and Surgery (CARS) <16, 2002, Paris, France>

Rapid development of medical field, expanding knowledge base and new technologies require continuing medical education to achieve life long learning and to keep the surgeons up to date. Consequently, specific training is necessary to guarantee qualification of the surgeons. To overcome the current drawbacks of traditional training systems (on - the - job training, plastic models etc.) for labaroscopy / hysteroscopy an intelligent adaptable training environment has been realized using Virtual Reality (VR), Multimedia (MM) technology, and Intelligent Tutoring Systems (ITS).

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Müller-Wittig, Wolfgang K.; Mlynski, Gunter; Weinhold, Ivo; Bockholt, Ulrich; Voss, Gerrit

Nasal Airflow Diagnosis - Comparison of Experimental Studies and Computer Simulations

2002

Medicine Meets Virtual Reality 2002. Proceedings

Medicine Meets Virtual Reality (MMVR) <10, 2002, Newport Beach, CA, USA>

The lack of situed diagnostic tools providing insight into patient specific flow characteristics of the nasal airflow is one of the main problems in functional diagnosis. Diagnostics methods currently used do not provide the necessary information for flow analysis. But the flow distribution is essential for a physiological repiration, in particular for cleaning moistening and tempering of the inhaled air as well as for the olfactory function of the nose. To overcome this current situation a cooperation project of the ENT surgeons and computer graphic engineers was established to develop the computer assisted planning system STAN (Simulation Tool for Airflow in the human Nose) combining Computer Fluid Dynamics (CFD) with advanced Computer Graphic Technology. The idea of the STAN system is to perform patient specific airflow simulations in the patient's nasal cavities. Therefore a geometrical model of the nasal airways is derived form the patient's tomography scans. A discretization of the surrounded flow volume is made by a computational grid. To establish the flow simulation Finite Element Methods are performed on the grid. A tailored visualization is offered to the surgeon that overlaps the flow pattern to the patient's tomography data shown in the coronal sagittal and transversal plane. The surgeon can not only analyze the patient's current respiration situation he has also the possibility to describe the planned surgical intervention. The goal is to simulate the flow distribution that can be expected after the surgical intervention and to offer a possibility to validate various surgical strategies. To verify the simulation results experimental investigation and measurements are made in nasal models. Silicon Models of patient's nose channels are made to analyze flow characteristics The CT or MR scans of the same patients are used as input data for the simulation. The experimental outcome is compared to the simulation results to validate this diagnostic approach.

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Reiners, Dirk; Voss, Gerrit; Behr, Johannes

OpenSG: Basic Concepts

2002

OpenSG Symposium <1, Darmstadt>

One of the main shortcomings of current scenegraphs is the inability to support multi thread-safe data. Another area that leaves things to be desired is extensibility. This work describes a system that allows multiple asynchronous threads to independently manipulate the scenegraph without interfering. This demands replication of data. As scenegraph data can get very big, a distinction of structural and content data is introduced, and a method to replicate the latter only if necessary. To make the whole concept generic and easily extensible, Reflectivity is introduced to the system. Besides allowing to manage multiple independent threads the described approaches can also be used for generic scenegraph access ,e.g. for loader/writer and GUIs. An extension allows also to the use the developed methods for cluster support.

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Bockholt, Ulrich; Mlynski, Gunter; Weinhold, Ivo; Müller-Wittig, Wolfgang K.; Voss, Gerrit

Simulation of the Nasal Airflow - Generation and Evaluation of a Patient Specific Flow

2002

Second European Medical and Biological Engineering Conference. Proceedings Vol. 2

European Medical and Biological Engineering Conference (EMBEC) <2, 2002, Vienna, Austria>

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Bisler, Alexander; Bockholt, Ulrich; Kordaß, Bernd; Suchan, M.; Voss, Gerrit

The Virtual Articulator

2002

International Journal of Computerized Dentistry

The virtual articulator (VA) is intended for use as a tool for the analysis of the complex static and dynamic occlusal relations. Its chief application is in individual diagnosis and the simulation of the mechanical articulator. As entry data, the VA requires digital, 3-dimensional representations of the jaws and patient-specific data on jaw movement. It then simulates jaw movement and provides a dynamic visualization of the occlusal contacts. If no patient-specific data are available, the modus operandi of the mechanical articulator can be simulated. Virtual reality (VR) techniques applied in computer-aided diagnosis are revolutionizing medical routine in many disciplines. Particularly in the field of dental engineering, VR combined with CAD/CAM technology has great potential in implant planning and design in terms of greater precision and shorter treatment duration. The geometry of teeth can be digitized, the implant models can be designed with specialized CAD systems, and the final implants can be manufactured with a CNC machine. In this context the virtual articulator completes the digital manufacturing process.

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Bisler, Alexander; Bockholt, Ulrich; Voss, Gerrit

The Virtual Articulator - Applying VR Technologies to Dentistry

2002

Sixth IEEE International Conference on Information Visualisation 2002. Proceedings

IEEE International Conference on Information Visualization (IV) <6, 2002, London, UK>

The use of Virtual Reality (VR) techniques for Computer-Aided Diagnosis is revolutionizing the medical routing in various medical disciplines. Especially in the field of dentistry VR in combination with CAD/CAM technologies offers a high potential for implant planning/design resulting in a higher accuracy and a shorter therapy time period. The geometry of the teeth is recognisable and digitisable using an intraoral camera, the implant models can be designed with specialized CAD systems and the final implants are generated using a CNC machine. In this context the "Virtual Articualtor" (VA) completes the digital manufacturing pipeline and offers the possibility to consider patient-specific jaw biomechanics in the implant generation process. The objective of this project is the development of a system for dental occlusion diagnosis. For this important diagnosis in today's dental routine the mechanical articulator is used. The VA simulates and augments the functionalities of the mechanical articulator. Therefore it takes a digital 3-D representation of the jaws as input data, generates a simulation of the jaw movements, and delivers a dynamical visualization of the occlusion points. The high technical demands to the system are given through the high accuracy necessary for dental applications and the large models that have to be handled in the system.

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Kordaß, Bernd; Gärtner, Christian; Söhnel, Andreas; Bisler, Alexander; Voss, Gerrit; Bockholt, Ulrich; Seipel, Stefan

The Virtual Articulator in Dentistry: Concept and Development

2002

The Dental Clinics of North America

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Bockholt, Ulrich; Müller-Wittig, Wolfgang K.; Los Arcos, José Luis; Oppelt, Peter; Stähler, Jan; Voss, Gerrit

Enhanced Training Environment for Minimally Invasive Surgery

2001

Proceedings of the 10th IEEE International Workshop on Enabling Technologies: Infrastructure for Collaborative Enterprises

IEEE International Workshop on Enabling Technologies: Infrastructure for Collaborative Enterprises (WET ICE) <10, 2001, Cambridge, MA, USA>

Rapid development of medical field, expanding knowledge base and new technologies require continuing medical education to achieve life long learning and to keep the surgeons up to date. Consequently, specific training is necessary to guarantee qualification of the surgeons. To overcome the current drawbacks of traditional training systems (on-the-job training, plastic models etc.) for laparoscopy/hysteroscopy an intelligent adaptable training environment has been realised using Virtual Reality (VR), Multimedia (MM) technology, ans Intelligent Tutoring Systems (ITS)

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Voss, Gerrit; Bisler, Alexander; Bockholt, Ulrich; Müller-Wittig, Wolfgang K.; Schäffer, Albert

ICAPS - An Integrative Computer-Assisted Planning System for Pedicle Screw Insertion

2001

Medicine Meets Virtual Reality 2001. Proceedings

Medicine Meets Virtual Reality (MMVR) <9, 2001, Newport Beach, CA, USA>

Robot Assisted Surgery (RAS) Systems win more and more recognition in the field of orthopaedics. Especially in Hip Surgery RAS has proved to be suited for application in medical routine. Often Robot Assisted Surgery Systems consist of a planning- and an interoperative component. According to specifications done with the planning software the tools are driven. Benefits of the robot assisted surgery should be higher precision and a better surgical outcome. In the co-operation project of several Fraunhofer Institutes "RoMed" (Robots and Manipulators for Medical Application) an exemplary application of robot aided spine surgery is developed. The planning software used in this context is proposed in the remaining article.

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Müller-Wittig, Wolfgang K.; Bockholt, Ulrich; Schäffer, Albert; Voss, Gerrit; Haberland, N.; Börner, Martin

Integrative Preoperative Planning for Pedicle Screw Inseration

2001

Computer Assisted Orthopaedic Surgery. Proceedings 2001

Annual Meeting of the International Society for Computer Assisted Orthopaedic Surgery (CAOS) <2001, USA>

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Müller-Wittig, Wolfgang K.; Bockholt, Ulrich; Los Arcos, José Luis; Oppelt, Peter; Stähler, Jan; Voss, Gerrit

LAHYSTOTRAIN - VR-based Intelligent Training Environment for Laparoscopy and Hysteroscopy

2001

Virtual Reality International Conference (VRIC) 2001. Proceedings

Virtual Reality International Conference (VRIC) <2001, Laval, France>

Rapid developments in the medical field, as an expanding knowledge base and emerging new technologies require continuing medical education to achieve life long learning and to keep the surgeons up to date. Consequently, specific training is necessary to guarantee qualification of the surgeons. The goal of LAHYSTOTRAIN is to overcome the current drawbacks of traditional training methods for laparoscopic/ hysteroscopic procedures. A computer-assisted simulator for training and quality control in laparoscopy and hysteroscopy is developed using Virtual Reality (VR), Multimedia (MM) technology, and Intelligent Tutoring Systems (ITS).

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Müller-Wittig, Wolfgang K.; Bisler, Alexander; Bockholt, Ulrich; Los Arcos, José Luis; Oppelt, Peter; Stähler, Jan; Voss, Gerrit

Lahystotrain: Development and Evaluation of a Complex Training System for Hysteroscopy

2001

Medicine Meets Virtual Reality 2001. Proceedings

Medicine Meets Virtual Reality (MMVR) <9, 2001, Newport Beach, CA, USA>

Hysteroscopy has already become an irreplaceable method in gynaecoloic diagnosis and therapy. In the diagnostic case the hysteroscope with a 30° optic is insert transvaginally, in the therapeutic case the resctoscope with a 12° optic is used. The endoscoppic intervention requires special surgical skills for endoscope handling and remote instrument control. To acquire these skills currently hands-on training in clinical praxis has become standard, which is linked with higher danger for the women. To overcome current drawbacks of traditional training methods the European project LAHYSTOTRAIN was set up, that tries to combine Virtual Reality (VR), Multimedia (MM) technology, and Intelligent Tutoring Systems (ITS) to develop an alternative training system for hysteroscopic interventions. The first prototype of the LAHYSTOTRAIN demonstrator has been shown on several European conferences. An evaluation of the system was performed, with the idea, to collect feedback and impressions, that should be considered in further developments. This paper presents the LAHYSTOTRAIN prototype and the results of these evaluations.

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Becker, Mario; Müller-Wittig, Wolfgang K. [Betreuer]; Felger, Wolfgang [Betreuer]; Voss, Gerrit [Betreuer]

Registration of anatomical structures based on high frequency ultrasound data for intraoperative support

2001

Darmstadt, TU, Diplomarbeit, 2001

In modern medicine, computer support becomes more and more important. Especially the combination of operation planing and the use of the planing results during an operation can help to optimize the work of surgeons. To use the planing data intraoperatively, the virtual world, containing the planing information must be matched with the real situation in the operation room. This is the goal of the Registration process. It determines a transformation to project preoperative data onto the patient inside the operation room. Actually this registration is done by fixing screws to the patient, which can be found within the CT dataset and measured mechanically during the operation. Affixing these screws efforts an additional operation and is an additional risk for the patient. The goal of this work was the evaluation of an alternative approach for the registration, using an intraoperative ultrasoundsystem, which is able to measure anatomical landmarks. To realize this task, a suited matching algorithm is used. This algorithm works on the segmented object of the anatomical region on one hand and on contours of the same region, measured by an intraoperatively attached ultrasound device on the other hand. The matching algorithm will find the transformation, which projects the contours onto the surface of the anatomical region. This transformation is the registration. In this diploma thesis a capable matching algorithm was founds and a system implementing this registration approach was developed and evaluated.

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Bergsträßer, Sonja; Reiners, Dirk [Betreuer]; Voss, Gerrit [Betreuer]

Shading Languages for Scenegraph Systems

2001

Darmstadt, TU, Studienarbeit, 2001

Die Beschreibung von Oberflächeneigenschaften für das Computergraphik Rendering, kann eine schwierige Aufgabe sein. Um die Berechnung und die Integration in Graphikhardware zu vereinfachen, wurden eine Anzahl Beleuchtungsmodelle entwickelt. Diese Modelle machen es einfach und effizient Beleuchtung zu definieren und zu berechnen, limitieren jedoch die Ausdrucksstärke. Als eine Konsequenz daraus wurden andere Modelle entwickelt, die in high-end Animationen verwendet werden. Am flexibelsten ist die Benutzung einer Shading Language, die dem Designer einen großen Freiheitsgrad gibt kombiniert mit einer Abstraktion des unterliegenden Renderingsystems. Die am meisten bekannte und benutzte ist Pixar's RenderMan. Echtzeit rendering erreicht einen Punkt an dem die Ausdrucksmöglichkeiten, der standard Beleuchtungsmodelle nicht mehr ausreicht, um die gewünschten Oberflächeneffekte zu beschreiben. Einige Gruppen versuchen nun die Mächtigkeit einer Shading Language und die echtzeit Grafik zu kombinieren. Alle diese Systeme sind jedoch eigenständig und nicht Teil einer Visualisierungsumgebung. Diese Tatsache begrenzt ihre Nützlichkeit und verhindert, daß sie die bestmögliche Performance erreichen. Für diese Arbeit wurden die existierenden Shading Languages analysiert mit dem Ziel sie in einen modernen high level Scenengraphen, wie OpenSG, zu integrieren. Das Resultat dieser Analyse ist eine Shading Language, basierend auf der Stanford Real Time Shading Language. Um diese Sprache übersetzen zu können wurde ein Compiler implementiert. Der Compiler übersetzt mathematische Beschreibungen in Graphikprogrammierungsbefehle. Die Informationen, die in der Eingabedatei gegeben sind werden extrahiert und zu verschiedene Datenrepräsentationen weiterverarbeitet. Diese Repräsentationen werden danach zur Zwischendarstellung kombiniert, welche die Basis für die strukturelle Analyse und die Code Generierung bildet. Der Compiler kann mathematische Beschreibungen von Standard-OpenGL Materialeigenschaften und Lichtquellen in Programmcode, der in einen OpenSG Scenengraph eingefügt werden kann, abbilden. Er arbeitet mit mehren Texturen durch die Benutzung einer multi-pass Technik und unterstützt die dynamische Texturkoordinaten- erzeugung. Das System ist skalierbar gebaut, so daß weitere Funktionalitäten einfache hinzugefügt werden können.

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Knöpfle, Christian; Voss, Gerrit

An Intuitive VR User Interface For Design Review

2000

Proceedings of the Working Conference on Advanced Visual Interface. AVI 2000

Working Conference on Advanced Visual Interface (AVI)<2000, Palermo, Italy>

In today's automotive industry there is an increasing demand for VR technology, because it provides the possibility to switch from cost and time insensitive physical mock up's (PMU) to digital mock up's (DMU). Unfortunately many current VR applications are either limited in the way people can interact with them, or provide a large set of functions, which are hard to use. In this paper we present the design of a VR user interface for applications in the area of digital design review. The basic requirements of such an UI are the ease of use, and the ability to work simultaneosly with a group of people on one system. Furthermore we investigate the functional requirements for this kind of application, including navigation, manipulation, examination and documentation of flaws in the design of the models. Documentation is stored as HTML and could therefore be easily transmitted between different parties. The design of the user interface is based on the basic interaction tasks (BIT's), introduced by Foley et. al., which allow to build complex functionality on top of only a few interaction metaphors. Finally we evaluate the concept on a prototype implementation, done in cooperation with BMW AG.

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Müller, Wolfgang; Bockholt, Ulrich; Voss, Gerrit; Lahmer, Armin; Börner, Martin

Computer Assisted Preoperative Planning System for Total Knee Replacement

2000

Computer Assisted Orthopaedic Surgery. Proceedings

Annual North American Program on Computer Assisted Orthodpaedic Surgery <4, 2000, Pittsburgh, PA, USA>

Total knee replacement (TKR) is a common orthopaedic surgical intervention and includes the removal of bone sections from the end of the femur and the top of the tibia for replacement by prosthetic components. Pain relief and functional improvement are predictable clinical results. But the accuracy of the alignment affects the surgical outcome and the longevity of the prosthesis. Hence, current total knee implantation systems attempt to align the knee joint in the mechanical axis for placement of the total knee components. These approaches use templates and plain radiographs for preoperative planning and alignment devices for bone cuts. To overcome the inherent inaccuracy of the presently used systems a computer-assisted planning system has been developed delivering the necessary control data for the intraoperative surgical robot system.

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Voss, Gerrit; Ecke, Ulrich; Müller, Wolfgang; Bockholt, Ulrich; Mann, Wolf

How to Become the "High Score Cyber Surgeon" - Endoscopic Training Using the Nasal Endoscopy Simulator (NES)

2000

Computer Assisted Radiology and Surgery (CARS) 2000. Proceedings

Computer Assisted Radiology and Surgery (CARS) <14, 2000, San Francisco, CA, USA>

Rapid development in the medical field, an expanding knowledge base and upcoming technologies require a continuing medical education to achieve life long learning and to keep the surgeons up to date. Consequently, specific training is necessary to guarantee the qualification of the surgeon. In recent years several training systems have been developed using Virtual Reality (VR) techniques to overcome the current drawbacks of traditional training systems (on-the-job training, plastic models etc.). In a co-operation project of University Hospital in Mainz (Department of Otalaryngology Head and Neck Surgery) and the Technical University in Darmstadt the Nasal Endoscopy Simulator (NES) is developed. Similar to a scenario in a computer game several tasks grouped into levels have to be solved during the training process. These levels are starting with simple tasks in abstract virtual environments to train the handling of the endoscope and they are ending with scenarios using complex models of the endonasal sinus to train orientation as well as diagnostic and therapeutic procedures. During a simulated interventions errors of the trainee, for example collisions of instruments and high sensitive tissues, are detected and evaluated. The integrative adaptable training environment provides new opportunities in medical education and enhances the medical standard curriculum. This concept has a general applicability to other medical fields.

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Bockholt, Ulrich; Voss, Gerrit; Müller, Wolfgang

Innovative Approaches in Computer-Assisted Surgery

2000

Sixth International Conference on Control, Automation, Robotics and Vision (ICARCV 2000). Conference Proceedings

International Conference on Control, Automation, Robotics and Vision (ICARCV) <6, 2000, Marina Mandarin, Singapore>

Total knee replacement (TKR) is a common orthopaedic surgical intervention and includes the removal of bone sections from the end of the femur and the top of the tibia for replacement by prosthetic components. Pain relief and functional improvement are predictable clinical results. But the accuracy of the alignment affects the surgical outcome and the longevity of the prosthesis. Hence, current total knee implantation systems attempt to align the knee joint in the mechanical axis for placement of the total knee components. These approaches use templates and plain radiographs for preoperative planning and alignment devices for bone cuts. To overcome the inherent inaccuracy of the presently used systems a computer-assisted planning system has been developed delivering the necessary control data for the intraoperative surgical robot system.

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Voss, Gerrit; Bockholt, Ulrich; Los Arcos, José Luis; Müller, Wolfgang; Oppelt, Peter; Stähler, Jan

Lahystotrain: Intelligent training system for Laparoscopy and Hysteroscopy

2000

Medicine Meets Virtual Reality 2000. Proceedings

Medicine Meets Virtual Reality (MMVR) <8, 2000, Newport Beach, CA, USA>

Rapid developments in the medical field, as an expanding knowledge base and emerging new technologies require continuing medical education to achieve life long learning and to keep the surgeons up to date. Consequently, specific training is necessary to guarantee qualification of the surgeons. The goal of LAHYSTOTRAIN is to overcome the current drawbacks of traditional training methods for laparoscopic/hysteroscopic procedures. A computer-assisted simulator for training and quality control in laparoscopy and hysteroscopy is developed using Virtual Reality (VR), Multimedia (MM) technology, and Intelligent Tutoring Systems (ITS).

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Müller, Wolfgang; Bockholt, Ulrich; Voss, Gerrit; Lahmer, Armin; Börner, Martin

Planning system for computer assisted total knee replacement

2000

Medicine Meets Virtual Reality 2000. Proceedings

Medicine Meets Virtual Reality (MMVR) <8, 2000, Newport Beach, CA, USA>

Total knee replacement (TKR) is a common orthopaedic surgical intervention and includes the removal of bone sections from the end of the femur and the top of the tibia for replacement by prosthetic components. Pain relief and functional improvement are redictable clinical results. But the accuracy of the alignment affects the surgical outcome and the longevity of the prosthesis. Hence, current total knee implantation systems attempt to align the knee joint in the mechanical axis for placement of the total knee components. These approaches use templates and plain radiographs for preoperative planning and alignment devices for bone cuts. To overcome the inherent inaccuracy of the presently used systems a computer-assisted planning system has been developed delivering the necessary control data for the intraoperative surgical robot system.

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Bockholt, Ulrich; Mlynski, Gunter; Müller, Wolfgang; Voss, Gerrit

STAN - The simulation tool for airflow in the human nose

2000

Computer Assisted Radiology and Surgery (CARS) 2000. Proceedings

Computer Assisted Radiology and Surgery (CARS) <14, 2000, San Francisco, CA, USA>

Computer assisted planning systems based on patient specific tomography data has been proofed to be useful in several medical fields. Patient's tomography data can be shown in several views and can be enhanced with additional information useful for the planing process. The STAN (Simulation Tool for Airflow in the human Nose) system overlaps patient data and CFD (computer fluid dynamics) data resulting from flow simulations of the airflow in the patient's nose channel. To verify the simulation results experimental investigations, and measurements are made in nasal models. Silicon Models of patient's nose channels are made to analyze flow characteristics. The CT or MR scans of the same patients are used as input data for the simulation. The experimental outcome is compared to the simulation results to validate this diagnostic approach.

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Müller, Wolfgang; Bockholt, Ulrich; Lahmer, Armin; Voss, Gerrit; Börner, Martin

VRATS - Virtual-Reality-Arthroskopie-Trainingssimulator

2000

Der Radiologe

Unzufriedenheit mit den traditionellen Ausbildungsmethoden in der endoskopischen Chirurgie führte zur Entwicklung eines Arthroskopietrainingssimulators, der Computergraphik und Techniken der Virtuellen Realität (VR) einsetzt. Basierend auf einem kernspintomographischen Bilddatensatz konnte mit Hilfe von Bildverarbeitungsmethoden und Visualisierungstechniken ein realistisches dreidimensionales Modell des Kniegelenks mit allen diagnostisch relevanten anatomischen Strukturen generiert und in den Simulator integriert werden. Die VR-Benutzer-Schnittstelle des Arthroskopietrainingssimulators besteht aus 2 Hauptkomponenten, der 3D-Interaktion, die das Führen der Instrumente realisiert, und der 2D-Benutzungsoberfläche, die das visuelle Feedback und die Kontrolle der Trainingsitzung ermöglicht. Auf diese Weise ist ein intuitives Handling der Instrumente garantiert. Der Chirurg ist in der Lage, eine arthroskopische Untersuchung an einen virtuellen Kniegelenk durchzuführen. Dazu sind auch erste Ansätze zur Simulation von Gewebeverformung implementiert, die aufgrund von Instrumenteinwirkungen auftreten.

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Bockholt, Ulrich; Voss, Gerrit; Müller, Wolfgang

Anwendung der Virtuellen Realität in der Medizin

1999

Biomedical Journal

In der modernen Medizin spielt die Verarbeitung medizinischer Bilddaten eine wichtige Rolle. Bildgebende Verfahren wie Röntgen-, Ultraschall- oder Kernspintomographieaufnahmen liefern große Datenmengen, mit denen eine Diagnose erstellt und die Therapie geplant wird. Hierbei muß der Mediziner aus den zweidimensional präsentierten Bilddaten die dreidimensionale Anatomie erschließen. Um dabei Unterstützung zu geben, ist eine 3D-Rekonstruktion der anatomischen Strukturen von Nutzen. Unter einer 3D-Rekonstruktion versteht man den Vorgang, für eine anatomische Struktur ein dreidimensionales Modell aus den gegebenen Bilddaten abzuleiten. Diese dreidimensionalen Repräsentationen können genutzt werden, den Arzt bei der Diagnose und Therapieplanung zu unterstützen. Eine wichtige Voraussetzung dafür ist eine intuitive benutzerfreundliche Mensch-Maschine Schnittstelle. Um intuitiv durch computergenerierte dreidimensionale Szenen zu navigieren, werden Techniken aus dem Bereich der Virtuellen Realität (VR) eingesetzt. Seit 1993 werden in der Abteilung Visualisierung und Virtuelle Realität des IGD Anwendungen von Virtueller Realität (VR) entwickelt, die in unterschiedlichen Gebieten der Medizin eingesetzt werden können. Die Aktivitäten der Gruppe Medizin und VR liegen hauptsächlich in den folgenden Bereichen: - Anatomische Ausbildung - Chirurgisches Training - Operationsplanung In diesem Artikel werden einige aktuelle Projekte vorgestellt, die Möglichkeiten zeigen, VR in der Medizin einzusetzen.

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Bockholt, Ulrich; Mlynski, Gunter; Müller, Wolfgang; Voss, Gerrit

Patient Specific Simulation of the Endonasal Airflow

1999

Advanced Medical Image Processing. Proceedings 1999

Germany-Korea Joint Conference on Advanced Medical Image Processing <4, 1999, Darmstadt/Heidelberg>

Methods of Computational Fluid Dynamics (CFD) nowadays play an important role in the production process of the automotive industry. Progress made in recent years offers highly sophisticated airflow simulation models used in engineering for optimization and verification of aerodynamics. The key point of the Airflow Simulation Tool for Human Medical Application (ASTHMA) developed at the Darmstadt University of Technology in cooperation with the University Hospital in Greifswald is to use these techniques to support the rhinosurgeon in diagnosis and therapy planning. A system is developed that realizes a 3-D reconstruction of the endonasal cavaties based on computer tomography (CT) scans. This semiautomatic reconstruction method requires minimal manual intervention. The surface model is used to create an unstructured 3-D volume mesh suitable for Finite Volume simulations. In this way an individual simulation based on patient specific data can be realized. To verify the simulation result, experimental investigations, and measurements are made in nasal models at the University Hospital in Greifswald. The goal of this project is to investigate individual nasal complains and to detect respiratory disorders. Prior to performing a surgical procedure the surgeon should be able to simulate the disordered respiration and the optimized case expected after the intervention. In this way the effectiveness of surgical planing could be increased, resulting in a better surgical outcome.

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Bockholt, Ulrich; Ecke, Ulrich; Müller, Wolfgang; Voss, Gerrit

Realtime Simulation of Tissue Deformation for the Nasal Endoscopy Simulator (NES)

1999

Medicine Meets Virtual Reality 1999. Proceedings

Medicine Meets Virtual Reality (MMVR) <7, 1999, San Francisco, CA, USA>

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Bockholt, Ulrich; Müller, Wolfgang; Voss, Gerrit; Ecke, Ulrich; Klimek, Ludger

Realtime Simulation of Tissue Deformation for the Nasal Endoscopy Simulator (NES)

1999

Computer Aided Surgery

Endonasal sinus surgery requires a great amount of training before it can be adequately performed. The complicated anatomy involved, the proximity of relevant structures, and the variability of the anatomy due to inborn or iatrogenic variations make several complications possible. Today cadaver dissections are the "gold standard" for surgical training. To overcome the drawbacks of traditional training methods the Fraunhofer Institute for Computer Graphics is currently developing a highly interactive medical simulation system for nasal endoscopy and endonasal sinus surgery in cooperation with the Mainz University Hospital. For the simulation of a rhinoscopic procedure not only the realization of the 3-D interaction and the geometric representation of the anatomical structures is necessary, but also a real-time simulation of the deformation behavior constraint by the instrument collisions. The challenge is to close the gap between a maximal degree of realism and the needed real-time conditions.

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Bockholt, Ulrich; Mlynski, Gunter; Müller, Wolfgang; Voss, Gerrit

Using Simulation of the airflow in the human nose for rhinosurgical therapy planning

1999

Computer Assisted Radiology and Surgery (CARS) '99. Proceedings

Computer Assisted Radiology and Surgery (CARS) <13, 1999, Paris, France>

Methods of Computational Fluid Dynamics (CFD) nowadays play an important role in the production process of the automotive industry. Progress made in recent years offers highly sophisticated airflow simulation models used in engineering for optimization and verification of aerodynamics. The key point of the Airflow Simulation Tool for Human Medical Application (ASTHMA) developed at the Darmstadt University of Technology in cooperation with the University Hospital in Greifswald is to use these techniques to support the rhinosurgeon in diagnosis and therapy planning [1]. A system is developed that realizes a 3-D reconstruction of the endonasal cavaties based on computer tomography (CT) scans. This semiautomatic reconstruction method requires minimal manual intervention. The surface model is used to create an unstructured 3-D volume mesh suitable for Finite Volume simulations. In this way an individual simulation based on patient specific data can be realized. To verify the simulation result, experimental investigations, and measurements are made in nasal models at the University Hospital in Greifswald. The goal of this project is to investigate individual nasal complains and to detect respiratory disorders. Prior to performing a surgical procedure the surgeon should be able to simulate the disordered respiration and the optimized case expected after the intervention. In this way the effectiveness of surgical planing could be increased, resulting in a better surgical outcome.