Book•
An Introduction to Ray tracing
11 Feb 1989-
About: The article was published on 1989-02-11 and is currently open access. It has received 1178 citations till now. The article focuses on the topics: Ray tracing (graphics).
Citations
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TL;DR: This work considers the problem of grasping novel objects, specifically objects that are being seen for the first time through vision, and presents a learning algorithm that neither requires nor tries to build a 3-d model of the object.
Abstract: We consider the problem of grasping novel objects, specifically objects that are being seen for the first time through vision. Grasping a previously unknown object, one for which a 3-d model is not available, is a challenging problem. Furthermore, even if given a model, one still has to decide where to grasp the object. We present a learning algorithm that neither requires nor tries to build a 3-d model of the object. Given two (or more) images of an object, our algorithm attempts to identify a few points in each image corresponding to good locations at which to grasp the object. This sparse set of points is then triangulated to obtain a 3-d location at which to attempt a grasp. This is in contrast to standard dense stereo, which tries to triangulate every single point in an image (and often fails to return a good 3-d model). Our algorithm for identifying grasp locations from an image is trained by means of supervised learning, using synthetic images for the training set. We demonstrate this approach on two robotic manipulation platforms. Our algorithm successfully grasps a wide variety of objects, such as plates, tape rolls, jugs, cellphones, keys, screwdrivers, staplers, a thick coil of wire, a strangely shaped power horn and others, none of which were seen in the training set. We also apply our method to the task of unloading items from dishwashers.
959Â citations
Cites methods from "An Introduction to Ray tracing"
...Ray tracing (Glassner 1989) is a standard image rendering method from computer graphics....
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...Ray tracing [Glassner, 1989] is a standard image rendering method from computer graphics....
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TL;DR: A recursive method for evaluating the impulse response of an indoor free-space optical channel with Lambertian reflectors, which enables accurate analysis of the effects of multipath dispersion on high-speed indoor optical communication systems.
Abstract: A recursive method for evaluating the impulse response of an indoor free-space optical channel with Lambertian reflectors is presented. The method, which accounts for multiple reflections of any order, enables accurate analysis of the effects of multipath dispersion on high-speed indoor optical communication systems. A simple algorithm for computer implementation of the technique and computer simulation results for both line-of-sight and diffuse transmitter configurations are also presented. In both cases, it is shown that reflections of multiple order are a significant source of intersymbol interference. Experimental measurements of optical multipath, which help verify the accuracy of the simulations, are discussed. >
867Â citations
Book•
01 Jan 1997
TL;DR: This dissertation develops new Monte Carlo techniques that greatly extend the range of input models for which light transport simulations are practical, and shows how light transport can be formulated as an integral over a space of paths.
Abstract: Light transport algorithms generate realistic images by simulating the emission and scattering of light in an artificial environment. Applications include lighting design, architecture, and computer animation, while related engineering disciplines include neutron transport and radiative heat transfer. The main challenge with these algorithms is the high complexity of the geometric, scattering, and illumination models that are typically used. In this dissertation, we develop new Monte Carlo techniques that greatly extend the range of input models for which light transport simulations are practical. Our contributions include new theoretical models, statistical methods, and rendering algorithms. We start by developing a rigorous theoretical basis for bidirectional light transport algorithms (those that combine direct and adjoint techniques). First, we propose a linear operator formulation that does not depend on any assumptions about the physical validity of the input scene. We show how to obtain mathematically correct results using a variety of bidirectional techniques. Next we derive a different formulation, such that for any physically valid input scene, the transport operators are symmetric. This symmetry is important for both theory and implementations, and is based on a new reciprocity condition that we derive for transmissive materials. Finally, we show how light transport can be formulated as an integral over a space of paths. This framework allows new sampling and integration techniques to be applied, such as the Metropolis sampling algorithm. We also use this model to investigate the limitations of unbiased Monte Carlo methods, and to show that certain kinds of paths cannot be sampled. Our statistical contributions include a new technique called multiple importance sampling, which can greatly increase the robustness of Monte Carlo integration. It uses more than one sampling technique to evaluate an integral, and then combines these samples in a
803Â citations
04 Jun 1995
TL;DR: It has been demonstrated that it is possible to develop successful robot controllers in simulation that generate almost identical behaviours in reality, at least for a particular class of robot-environment interaction dynamics.
Abstract: The pitfalls of naive robot simulations have been recognised for areas such as evolutionary robotics. It has been suggested that carefully validated simulations with a proper treatment of noise may overcome these problems. This paper reports the results of experiments intended to test some of these claims. A simulation was constructed of a two-wheeled Khepera robot with IR and ambient light sensors. This included detailed mathematical models of the robot-environment interaction dynamics with empirically determined parameters. Artificial evolution was used to develop recurrent dynamical network controllers for the simulated robot, for obstacle-avoidance and light-seeking tasks, using different levels of noise in the simulation. The evolved controllers were down-loaded onto the real robot and the correspondence between behaviour in simulation and in reality was tested. The level of correspondence varied according to how much noise was used in the simulation, with very good results achieved when realistic quantities were applied. It has been demonstrated that it is possible to develop successful robot controllers in simulation that generate almost identical behaviours in reality, at least for a particular class of robot-environment interaction dynamics.
643Â citations
Book•
10 Oct 2002
TL;DR: Geometric Tools for Computer Graphics is an extensive, conveniently organized collection of proven solutions to fundamental problems that you'd rather not solve over and over again, including building primitives, distance calculation, approximation, containment, decomposition, intersection determination, separation, and more.
Abstract: From the Publisher:
Do you spend too much time creating the building blocks of your graphics applications or finding and correcting errors? Geometric Tools for Computer Graphics is an extensive, conveniently organized collection of proven solutions to fundamental problems that you'd rather not solve over and over again, including building primitives, distance calculation, approximation, containment, decomposition, intersection determination, separation, and more.
If you have a mathematics degree, this book will save you time and trouble. If you don't, it will help you achieve things you may feel are out of your reach. Inside, each problem is clearly stated and diagrammed, and the fully detailed solutions are presented in easy-to-understand pseudocode. You also get the mathematics and geometry background needed to make optimal use of the solutions, as well as an abundance of reference material contained in a series of appendices.
KEY FEATURES: * Filled with robust, thoroughly tested solutions that will save you time and help you avoid costly errors.
* Covers problems relevant for both 2D and 3D graphics programming.
* Presents each problem and solution in stand-alone form allowing you the option of reading only those entries that matter to you.
* Provides the math and geometry background you need to understand the solutions and put them to work.
* Clearly diagrams each problem and presents solutions in easy-to-understand pseudocode.
* Resources associated with the book are available at the companion Web site.
Author Biography: Philip Schneider leads a modeling and dynamic simulation software group at Walt Disney Feature Animation. Prior to that, his work at Apple and Digital Equipment Corporation in 3D graphics ranged from low-level interfaces to graphics libraries and interactive applications. He holds an M.S. in Computer Science from the University of Washington.
Dave Eberly is the president of Magic Software, Inc., a company known for its free source code and documentation for computer graphics, image analysis, and numerical methods. Previously, he was the director of engineering at Numerical Design Limited, the company responsible for the real-time 3D game engine, NetImmerse. His background includes a B.A. in mathematics from Bloomsburg University, M.S. and Ph.D. degrees in mathematics from the University of Colorado at Boulder, and M.S. and Ph.D. degrees in computer science from the University of North Carolina at Chapel Hill. Dave is author of 3D Game Engine Design, co-author with Philip Schneider of Geometric Tools for Computer Graphics, and author of the forthcoming Game Physics (Spring 2003).
597Â citations
References
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01 Aug 1979
TL;DR: If a few assumptions are made about the geometry of each object and about the conditions under which they are viewed, a much simplier algorithm can be used to approximate the refractive effect.
Abstract: Simple transparency algorithms which assume a linear transparency over an entire surface are the type most often employed to produce computer synthesized images of transparent objects with curved surfaces. Although most of the images created with these algorithms do give the impression of transparency, they usually do not look realistic. One of the most serious problems is that the intensity of the light that is transmitted through the objects is generally not proportional to the amount of material through which it must pass. Another problem is that the image seen behind the objects is not distorted as would naturally occur when the light is refracted as it passes through a material of different density.Use of a non-linear transparency algorithm can provide a great improvement in the realism of an image at a small additional cost. Making the transparency proportional to the normal to the surface causes it to decrease towards the edges of the surface where the path of the light through the object is longer. The exact simulation of refraction, however, requires that each sight ray be individually traced from the observer, through the picture plane and through each transparent object until an opaque surface is intersected. Since the direction of the ray would change as each material of differing optical density was entered, the hidden surface calculations required would be very time consuming. However, if a few assumptions are made about the geometry of each object and about the conditions under which they are viewed, a much simplier algorithm can be used to approximate the refractive effect. This method proceeds in a back to front order, mapping the current background image onto the next surface, until all surfaces have been considered.
134Â citations
Proceedings Article•
01 Aug 1986
34Â citations
01 Aug 1974
TL;DR: The addition to the list of available body types of two new bodies, the general ellipsoid and the 'arbitrary quadric surface', and the development of a geometry preprocessor program capable of producing GIFT input from a more limited, user-oriented, set of descriptions are described.
Abstract: : The tasks completed under this contract and described in the report are: (1) The addition to the list of available body types of two new bodies, the general ellipsoid and the 'arbitrary quadric surface'; (2) The development of a geometry preprocessor program capable of producing GIFT input from a more limited, user-oriented, set of descriptions; (3) Development of a BRL-COMGEOM model of the M109A1 tank. The first two tasks are described in some detail. The modeling task is embodied in an input deck for the GIFT code and is described briefly in the last section.
1Â citations