Fast Reliable Ray-tracing of Procedurally Defined Implicit Surfaces Using Revised Affine Arithmetic

Fast and reliable rendering of implicit surfaces is an important area in the field of implicit modelling. Direct rendering, namely ray-tracing, is shown to be a suitable technique for obtaining good-quality visualisations of implicit surfaces. We present a technique for reliable ray-tracing of arbitrary procedurally defined implicit surfaces by using a modification of Affine Arithmetic called Revised Affine Arithmetic. A wide range of procedurally defined implicit objects can be rendered using this technique including polynomial surfaces, constructive solids, pseudo-random objects, procedurally defined microstructures, and others. We compare our technique with other reliable techniques based on Interval and Affine Arithmetic to show that our technique provides the fastest, while still reliable, ray-surface intersections and ray-tracing. We also suggest possible modifications for the GPU implementation of this technique for real-time rendering of relatively simple implicit models and for near real-time for complex implicit models

Graphics Intro 64kB Using OpenGL

Práce popisuje hlavní části implementace grafického intra s omezenou velikostí. Popsány jsou použité minimalistické techniky a způsob procedurální výroby textur a jednoduchých i složitých 3D objektů. Dále jsou vysvětleny způsoby načítání, úpravy a animace objektů a způsoby vytvoření použitých efektů.Document describes implementation of the graphical demo with limited size. Described are used minimalistic techniques and the methods of procedurally created textures and both simple and complex 3D objects. There are explained methods for loading, editing and animating objects and ways to create used effects.

Analysis of Finite Microstrip Structures Using an Efficient Implementation of the Integral Equation Technique

An efficient numerical implementation of the Integral Equation technique (IE) has been developed for the analysis of the electrical characteristics of finite microstrip structures. The technique formulates a volume version of the IE for the finite dielectric objects, and a standard surface IE technique for the metallic areas. The system of integral equations formu- lated are solved with special numerical techniques described in this paper. The input impedances of several microstrip antennas have been computed, showing good agreement with respect mea- surements. The technique has shown to be accurate even for complex geometries containing several stacked dielectric layers. The radiation patterns of the structures have also been com- puted, and measured results from real manufactured hardware confirm that backside radiation and secondary lobes are accurately predicted by the theoretical model. The paper also discuss a suitable excitation model for finite size ground planes, and investigates the possibilities for an independent meshing of the metallic areas and the dielectric objects inside a given geom- etry. The practical value of the approach derived is that microstrip circuits can be designed minimizing the volume and size of the dielectric substrates.This work has been supported bythe Spanish National Project ESP2001-4546-PE, and RegionalSeneca Project PB/4/FS/02

Accurate and efficient algorithms for boundary element methods in electromagnetic scattering: a tribute to the work of F. Olyslager

Boundary element methods (BEMs) are an increasingly popular approach to model electromagnetic scattering both by perfect conductors and dielectric objects. Several mathematical, numerical, and computational techniques pullulated from the research into BEMs, enhancing its efficiency and applicability. In designing a viable implementation of the BEM, both theoretical and practical aspects need to be taken into account. Theoretical aspects include the choice of an integral equation for the sought after current densities on the geometry's boundaries and the choice of a discretization strategy (i.e. a finite element space) for this equation. Practical aspects include efficient algorithms to execute the multiplication of the system matrix by a test vector (such as a fast multipole method) and the parallelization of this multiplication algorithm that allows the distribution of the computation and communication requirements between multiple computational nodes. In honor of our former colleague and mentor, F. Olyslager, an overview of the BEMs for large and complex EM problems developed within the Electromagnetics Group at Ghent University is presented. Recent results that ramified from F. Olyslager's scientific endeavors are included in the survey

Tracking Skin-Colored Objects in Real-Time

We present a methodology for tracking multiple skin-colored objects in a monocular image sequence. The proposed approach encompasses a collection of techniques that allow the modeling, detection and temporal association of skincolored objects across image sequences. A non-parametric model of skin color is employed. Skin-colored objects are detected with a Bayesian classifier that is bootstrapped with a small set of training data and refined through an off-line iterative training procedure. By using on-line adaptation of skin-color probabilities the classifier is able to cope with considerable illumination changes. Tracking over time is achieved by a novel technique that can handle multiple objects simultaneously. Tracked objects may move in complex trajectories, occlude each other in the field of view of a possibly moving camera and vary in number over time. A prototype implementation of the developed system operates on 320x240 live video in real time (28Hz), running on a conventional Pentium IV processor. Representative experimental results from the application of this prototype to image sequences are also presented. 1

ZJU ReLER Submission for EPIC-KITCHEN Challenge 2023: Semi-Supervised Video Object Segmentation

The Associating Objects with Transformers (AOT) framework has exhibited exceptional performance in a wide range of complex scenarios for video object segmentation. In this study, we introduce MSDeAOT, a variant of the AOT series that incorporates transformers at multiple feature scales. Leveraging the hierarchical Gated Propagation Module (GPM), MSDeAOT efficiently propagates object masks from previous frames to the current frame using a feature scale with a stride of 16. Additionally, we employ GPM in a more refined feature scale with a stride of 8, leading to improved accuracy in detecting and tracking small objects. Through the implementation of test-time augmentations and model ensemble techniques, we achieve the top-ranking position in the EPIC-KITCHEN VISOR Semi-supervised Video Object Segmentation Challenge.Comment: Top 1 solution for EPIC-KITCHEN Challenge 2023: Semi-Supervised Video Object Segmentatio

Graphic frameworks for managing component oriented graphic systems

This thesis presents a model graphic framework. It uses traditional graphic principles such as display file concepts to generate frameworks. It implements object oriented patterns such as inheritance polymorphism etc. to reuse the graphic framework for the object oriented graphic applications; This thesis suggests component technology such as Microsoft COM technology to make the frameworks effective. The thesis identifies the advantage of Component Oriented Technology over Object Oriented Technology. The procedure for development of a Component is complex. Even the client procedure for using the component is also complex. This thesis presents a model procedure for the development of a simple beeper component and its client program to demonstrate the complexity of the component technology; The thesis adopts some of the existing pattern frames to make the implementation graphic components simple. It also presents some techniques to make the client procedures for using a component simple; The advantages of the model graphic frameworks presented in this thesis are as follows: (1) The Graphic application developer can develop Graphic Components (graphic COM objects) like simple C++ objects using the frameworks. (2) The client who uses these components for the development of the graphic applications can use these components (COM object) like simple C++ objects; That means the components (COM objects) behave like simple C++ objects for development and for usage but they are COM objects; The models presented in this thesis can be views in two layers. The first layers focus on increasing the degree of reusability of graphic objects to minimize cost. In this connection the model is tested by implementing PCB (Printed circuit board) Graphic Application for representing several graphic elements of different types minimizing the number of component. This enables graphic applications run on lower-end systems; The second layers try to implement graphic COM components like simple C++ objects. Abstract COM object framework is created and several graphic COM objects are created for testing this model. Client side wrapper component is also implemented and tested for using complex graphic COM object like simple C++ objects; Chapter three and five will presents detailed description of these models. Output Screen of graphic Applications is presented in Appendix B. (Abstract shortened by UMI.)

Object-Oriented Paradigms for Modelling Vascular\ud Tumour Growth: a Case Study

Motivated by a family of related hybrid multiscale models, we have built an object-oriented framework for developing and implementing multiscale models of vascular tumour growth. The models are implemented in our framework as a case study to highlight how object-oriented programming techniques and good object-oriented design may be used effectively to develop hybrid multiscale models of vascular tumour growth. The intention is that this paper will serve as a useful reference for researchers modelling complex biological systems and that these researchers will employ some of the techniques presented herein in their own projects