Photo-realistic image synthesis in volume rendering for rapid prototyping and CAM applications (draft)

This document describes some preliminary results of the application of direct volume visualization and realistic image synthesis techniques in Computer Aided Manufacturing (CAM) field. The final goal is to analyze the use volume data representation and direct volume visualization techniques respectively as basic geometric element and rendering method for numerical control (NC) process planning and simulation. In particular we want to study their application in the process of human organs replication by rapid prototyping techniques. Volume rendering techniques will be used to evaluate the geometric reconstruction of volumetric data (e.g. parts of human body extracted from a CT scan as the carotid arteries), in order to obtain the best polygonal approximation of a dataset. The polygonal model resulting from this evaluation stage will be used to drive its physical reconstruction via rapid prototyping. A volume rendering program, called VolCastIA, is presented. VolCastIA is a software environment built to evaluate the use of state of the art image synthesis methods in the volume rendering context

A medical volume visualization system supporting head-tracked stereoscopic viewing and direct 3D interaction

We have developed an experimental medical volume visualization system supporting head-tracked stereoscopic viewing registered with direct 3D interaction. Our aim is to assess the suitability of these techniques for surgical planning tasks in real medical settings. In particular, vascular surgeons examining the distal site of the aneurysmatic sack are assisted by visualizing the artery aneurysm in depth. A better understanding of such complex spatial structures is achieved by incorporatingmotion parallax and stereoscopic cues to depth perception not available from static images. Our display when positioned as a surgical table provides theimpression of looking down at the patient in a naturalistic way. With simple head motions, good positions for observing the pathology are quickly established.1997-09Pisa, ItalyProceedings 15th International EuroPACS Meetin

Sviluppo dei codici di simulazione per il trasporto dei frammenti di fissione e per il computo degli effetti radiativi

In questo rapporto si sviluppano i codici ab initio che permettono di risolvere le problematiche del rilascio energetico dei frammenti di fissione e del bilancio della radiazione nel gas. Questo lavoro può essere portato a compimento solo se si accoppiano i codici coi risultati derivanti dall'analisi fluidodinamica. In particolare è stato necessario affiancare ad un codice di fluidodinamica nativo del CRS4 (KARALIS), due nuovi codici che permettono di studiare in geometrie tridimensionali i meccanismi di cessione di calore al gas da parte dei frammenti di fissione (FF_HEAT) e la ridistribuzione dell’energia così assorbita a causa dei processi radiativi innescati dalle alte temperature raggiunte in camera di combustione (PHOTON). Il rapporto illustra i dettagli sul funzionamento di codici e le tecniche di sviluppo di FF_HEAT e PHOTON e gli algoritmi Montecarlo sui quali sono basati. Inoltre viene descritta l’architettura ed il funzionamento del codice completo che simula la fisica completa del gas nella camera di combustione e le interazioni tra i singoli codici

Design of the hardware abstraction layer for the 3d acquisition system of AILUN and CRS4

During development of software we’ve discovered that would be better divide hardware management from all the other parts of code. We needed to achieve many results: a modular, manageable and portable code (from windows to Linux); support of a loto of cameras and runtime choice of cameras; de-coupling from management of different devices inside th acquisition system; unified driver handling system (open, close, RTacquire e DSacquire) simplifies drivers development by people who do not belong to the team. To achieve these goals we have re-engineered the code that communicates with the hardware and we’ve developed a Hardware Abstraction Layer using techniques well known in software engineering (design patterns, petri nets, and so on)

A shapes based geometric modeler for mesh++, API description

One of the purposes of the ViVa Project is the reconstruction of geometrical models from a suitable set of data provided by non invasive medical analyses like Computed Tomography (CT) or Magnetic Resonance Imaging (MRI). To do this, we first segment the vessel geometry from the data sets using techniques such as active snakes, and then reconstruct geometrical models using the XOX SHAPES geometric modeler, and in particular its MicroTopology features. In order to perform blood flow simulation on these models, we need to mesh them, and so we use the Mesh++ grid generator to process the models and create a two-dimensional grid for the surfaces and a three-dimensional one for the vessel lumen

Catheter insertion simulation with combined visual and haptic feedback

We have developed an experimental catheter insertion system supporting head-tracked stereoscopic viewing of volumetric reconstruction registered with direct haptic 3D interaction. The system takes as input patient data acquired with standard medical imaging modalities and regards it as a visual and haptic environment whose parameters are defined using look-up tables. By means of a mirror, the screen seems to be positioned like a surgical table providing the impression of looking down at the patient in a natural way. Co-registering physical and virtual spaces beforehand means that the patient appears at a fixed physical positionj on the surgical table and inside the workspace of the PHANToM device which controls catheter insertion. During the insertion procedure the system provides perception of the force of penetration and positional deviation of the inserted catheter

Anatomical shape reconstruction and manufacturing: solving topological changes of lumen vessel trough geometric approach

Over the last years there has been an increasing growth of interest in Rapid Prototyping (RP) techniques applied to various fields of medicine. RP makes it possible, in vascular surgery, to produce accurate anatomic replicas of patient vessels. These replicas can help the customization of surgical invasive interventions such as in situ stent-graft insertion in carotid region. The main goal of this work is to obtain high quality in lumen reconstruction and manufacturing replicas by RP technique. This goal is achieved through the complete control of each phase of the generating process. We present a semi-automatic method for carotid lumen reconstruction based on Boundary Representation (BRep). All parameters influencing the quality of the shape reconstruction are presented and discussed: shape acquisition, shape reconstruction and shape manufacturing. The shape acquisition starts by extracting the points belonging to the boundary of the lumen vessel, from Computer Tomography (CT) images. These points, parameterised in a vector, are the input data of the shape reconstruction algorithm based on B-Spline interpolation. The B-Spline type for representing curves and surfaces were chosen because of their properties of continuity and local control. In the shape reconstruction stage we had to face problems due to the topological change on the vessel structure. For vessel regions where there are not changes of topology, we use the closed B-Spline curves (belonging to adjacent acquisition planes) as generating curves to build a B-Spline surface. For vessel regions with at least a change of topology (ex. bifurcation region) our algorithm split automatically the involved curves to obtain three rectangular B-Spline patches. Such patches are joined together to obtain the bifurcation vessel lumen. The set of lumen surfaces is then inserted in a Boundary Representation in order to get a valid solid. To analyse the quality of the reconstructed shapes, the final object is compared with the acquisition image. This solid is correctly tessellated in triangles to produce the data format used by the RP devices (STL)

Tecniche di visualizzazione volumetrica di carotaggi

Technical Report 97/2

Realizzazione fisica di superfici non orientabili mediante prototipazione rapida

Il termine Prototipazione Rapida (RP da Rapid Prototyping, conosciuta anche come Solid Freeform Fabrication – SFF) si riferisce ad un insieme di tecnologie usate per costruire prototipi di oggetti tridimensionali a partire da modelli geometrici definiti solidi ricostruiti con programmi di progettazione assistita dal calcolatore (Computer Aided Design – CAD). Importanti applicazioni della Prototipazione Rapida si sono ampiamente diffuse negli ultimi anni in vari ambiti: si va dal campo industriale a quello biomedico a quello del design. La complessità geometrica delle forme solide da realizzare è conseguentemente aumentata e richiede lo studio sempre più accurato anche da un punto di vista matematico. Questo documento analizza le competenze matematiche necessarie per trattare la ricostruzione di oggetti dalla geometria particolare, come ad esempio le Superfici non orientabili (Nastro di Möbius, Bottiglia di Klein) per arrivare alla definizione di una loro parametrizzazione utile per la costruzione di modelli solidi stampabili direttamente con tecnica RP. In particolare, sono trattati i problemi legati alla generazione degli spessori necessari alla realizzazione fisica

Sistemi informatici avanzati per l'analisi stratigrafica archeologica

Questo documento descrive le potenzialità derivanti dall’applicazione di affermate tecniche e metodologie ICT nell’ambito dell’indagine di siti archeologici. Queste metodologie sono organizzate in una architettura di sistema informativo adeguato a supportare l’attività dell’archeologo per la ricerca, la didattica e la fruizione. L’architettura proposta cerca di estendere le potenzialità d’uso delle metodologie di analisi non distruttiva, delle tecniche di ricostruzione di geometrie di reperti, e delle tecniche di prototipazione rapida per la manifattura di reperti, utilizzati principalmente nella diagnosi e restauro di beni culturali, ad ambiti più estesi quali l’analisi stratigrafica archeologica. L’architettura si basa sugli strumenti software ed ambienti di sviluppo sperimentati nel Progetto Laboratorio Avanzato per la Progettazione e la Simulazione al Calcolatore