Spherical Sampling by Archimedes\u27 Theorem

In this paper we present a simple and efficient algorithm for generating uniformaly distributed samples on the unit sphere based on an Archimedes\u27 theorem. The implementation is straightforward and may be easily extended to include stratified sampling for variance reduction. Applications in image synthesis include solid angle measurement, irradiance computation, and rendering equation solution for geometrically complex environments

Specularity Detection Using Time-of-Flight Cameras

Time-of-flight (TOF) cameras are primarily used for range estimation by illuminating the scene through a TOF infrared source. However, additional background sources of illumination of the scene are also captured in the measurement process. This paper exploits conventional Lambertian and Phong's illumination models, developed for 2D CCD image cameras, to propose a radiometric model for a generic TOF camera. The model is used as the basis for a novel specularity detection algorithm. The proposed model is experimentally verified using real data

Progressive refinement rendering of implicit surfaces

The visualisation of implicit surfaces can be an inefficient task when such surfaces are complex and highly detailed. Visualising a surface by first converting it to a polygon mesh may lead to an excessive polygon count. Visualising a surface by direct ray casting is often a slow procedure. In this paper we present a progressive refinement renderer for implicit surfaces that are Lipschitz continuous. The renderer first displays a low resolution estimate of what the final image is going to be and, as the computation progresses, increases the quality of this estimate at an interactive frame rate. This renderer provides a quick previewing facility that significantly reduces the design cycle of a new and complex implicit surface. The renderer is also capable of completing an image faster than a conventional implicit surface rendering algorithm based on ray casting

Computer Aided Lighting for architects and designers

Designing lightings in a 3D-scene is a general complex task for building conception as it is submitted to many constraints such as aesthetics or ergonomics. This is often achieved by experimental trials until reaching an acceptable result. Several rendering softwares (such as Radiance) allow an accurate computation of lighting for each point in a scene, but this is a long process and any modification requires the whole scene to be rendered again to get the result. The first guess is empirical, provided by experience of the operator and rarely submitted to scientific considerations. Our aim is to provide a tool for helping designers to achieve this work in the scope of global illumination. We consider the problem when some data are asked for : on one hand the mean lighting in some zones (for example on a desktop) and on the other hand some qualitative information about location of sources (spotlights on the ceiling, halogens on north wall,...). The system we are conceiving computes the number of light sources, their position and intensities, in order to obtain the lighting effects defined by the user. The algorithms that we use bind together radiosity computations with resolution of a system of constraints

Penggunaan Pemrosesan Paralel Pada Radiosity Untuk Mempercepat Proses Rendering

Visualizing objects that are illuminated by light and reflected from its surrounding objects can be performed using radiosity method. In the method, a multitude of rays from a light source must be traced until it can be determined that the ray does not collide with any objects in the environment, or the ray intensity is too weak to be engaged in the final intensity calculation. The process of tracing the rays must be repeated for each ray that collides to any object. Based on this concept, it is no wonder that radiosity will take a lot of time in its rendering process. Fortunately, rays that need to be traced in radiosity are independent one another. A server-client parallel processing is used in this research to parallel the process in radiosity. Server will assign some rays to be traced to clients. After clients finished their jobs in tracing rays, they can send the result back to server to be used to render the objects. From the experiment, it can be concluded that the performance in paralleling the process in radiosity can be considered good. Increasing the number of clients can significantly reduce the time required to finish the job. Therefore a certain company can use several idle computers as clients to decrease the time required to get the final result. It can also be concluded as well that the system has some limits in employing the number of clients. At a certain point, adding more clients will not anymore decrease significantly the time required to get the result. This problem occurs from the phenomenon of the efficiency decremental as the number of clients increases

Parallel hierarchical global illumination

Solving the global illumination problem is equivalent to determining the intensity of every wavelength of light in all directions at every point in a given scene. The complexity of the problem has led researchers to use approximation methods for solving the problem on serial computers. Rather than using an approximation method, such as backward ray tracing or radiosity, we have chosen to solve the Rendering Equation by direct simulation of light transport from the light sources. This paper presents an algorithm that solves the Rendering Equation to any desired accuracy, and can be run in parallel on distributed memory or shared memory computer systems with excellent scaling properties. It appears superior in both speed and physical correctness to recent published methods involving bidirectional ray tracing or hybrid treatments of diffuse and specular surfaces. Like progressive radiosity methods, it dynamically refines the geometry decomposition where required, but does so without the excessive storage requirements for ray histories. The algorithm, called Photon, produces a scene which converges to the global illumination solution. This amounts to a huge task for a 1997-vintage serial computer, but using the power of a parallel supercomputer significantly reduces the time required to generate a solution. Currently, Photon can be run on most parallel environments from a shared memory multiprocessor to a parallel supercomputer, as well as on clusters of heterogeneous workstations

Étude et développement d'un simulateur d'échanges radiatifs dans des scènes 3D statiques et dynamiques surveillées par thermographie infrarouge

International audienc

2D Photo Converter: Modeling 3D Objects from 2D Photos Using OpenGL

The concept of modeling a 3D object based on 2D photos has indeed been widely discussed and researched among the computer vision professionals and virtual reality technologists. However, regardless of the many researches going on and the rapid technological development in 3D modeling world, the best method to render a 3D model that satisfies the requirement of minimum image pre-processing, maximum model-realism and minimum error percentage is yet to be studied. This report will lay out another technique of modeling 3D objects using a 2D photo by analyzing the possibility and accuracy of light intensity evaluation towards the model. The main objective of this study is to propose an alternative solution to 3D modeling techniques by using the information from a 2D photo. It is hoped that by applying the proposed solution, the constraint of costs and time in the current 3D modeling system could be reduced. The research focuses on bitmap photos and it applies the principles of light intensity and distance relativity in estimating the depth volume of the model. The application is built by using Microsoft Visual C++ 6.0 and utilizes OpenGL Application Programming Interface (API) in its code. However, the results of the experiments conducted in this research study shows that the formula used in the application might not be the best method to produce a 3D model from a 2D photo. Nonetheless, the idea of using light intensity valuations in producing 3D models could be the new solution in 3D modeling technology. The framework design and the ideas could be the base research for further development in the 3D modeling research and analysis study