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1994 Symposium on Volume Visualization, VVS 1994

作者： Arvo, James Novins, Kevin Program of Computer Graphics Cornell University 580 Engineering and Theory Center IthacaNY14853 United States IMAGIS/IMAG BP53 Grenoble Cedex 0938041 France

ISBN: (纸本)0897917413

In this paper we present a new approach to volume rendering in which curves of constant intensity in image space, or iso-contours, are computed directly for each view. The generated iso-contours can be used to drive various visualization and feature-detection algorithms. The approach imposes no restriction on the organization of the data points and can accommodate a large class of radiallysymmetric filter functions. The technique works well for both perspective and orthographic viewing projections. Each iso-contour is defined by an ordinary differential equation, which is solved numerically using a predictor-corrector method. A key element of the algorithm is the use of image intensity gradients, which we compute by means of a closed-form expression that holds at every point on the image plane. A caching algorithm is described that dramatically accelerates the gradient computations on large datasets. The algorithm is demonstrated on emission-only datasets. We conclude by describing a number of possible enhancements. © 1995 IEEE.

关键词： Volume rendering

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Transparency for computer synthesized images 79

Transparency for computer synthesized images

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6th Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1979

作者： Kay, Douglas Scott Greenberg, Donald Program of Computer Graphics Cornell University United States Sundance Productions Inc. Acme Cartoon Co. Inc. 7141 Envoy Ct. DallasTX75247 United States

ISBN: (纸本)0897910044

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. © 1979 ACM.

关键词： Transparency

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Visual equivalence: An object-based approach to image quality

Visual equivalence: An object-based approach to image qualit...

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16th Color Imaging Conference: Color Science and Engineering Systems, Technologies, and Applications

作者： Ferwerda, James A. Ramanarayanan, Ganesh Walter, Bruce Bala, Kavita Munsell Color Science Laboratory Center for Imaging Science Rochester Institute of Technology Rochester NY United States Department of Computer Science Cornell University Ithaca NY United States Program of Computer Graphics Cornell University Ithaca NY United States

ISBN: (纸本)9780892082810

In this paper we introduce a new approach to characterizing image quality: visual equivalence, Images are visually equivalent if they convey the same information about object appearance even if they are visibly different. In a series of psychophysical experiments we explore how object geometry, material, and illumination interact to produce images that are visually equivalent, and we identify how two kinds of transformations on illumination fields (blurring and warping) influence observers' judgments of equivalence. We use the results of the experiments to derive metrics that can serve as visual equivalence predictors (VEPs) and we generalize these metrics so they can be applied to novel objects and scenes. Finally we validate the predictors in a confirmatory study, and show that they reliably predict observer's judgments of equivalence. Visual equivalence is a significant new approach to measuring image quality that goes beyond existing visible difference metrics by leveraging the fact that some kinds of image differences do not matter to human observers. By taking advantage of higher order aspects of visual object coding, visual equivalence metrics should enable the development of powerful new classes of image capture, compression, rendering, and display algorithms.

关键词： Image quality

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Digital Color Output Conformity to ISO12647-7 Standards (GRACoL 2013 [CGATS21-2-CRPC6]) With the Use of Statistical Process Control (SPC)

Journal of Technology, Management, and Applied Engineering

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Journal of Technology, Management, and Applied Engineering 2023年第4期39卷 1-18页

作者： Dharavath, Haji Naik Program Coordinator for the BS degree in Graphics Technology Department of Computer Electronics & Graphics Technology Central Connecticut State University New BritainCT06050 United States

The purpose of this applied research was to apply the statistical process control (SPC) to determine the digital color output conformity to ISO12647-7 standards in a color managed digital printing workflow (CMDPW) over a period of 100 days (N = 100). The quality of digital color printing is determined by these influential factors: screening method applied, type of printing process, calibration method, device profile, ink (dry toner or liquid toner), printer resolution, and the substrate (paper). For this research, only the color printing attribute overall average color deviation (ACD;ΔE(2000)) was analyzed to examine the CMDPW process consistency in a day-to-day digital printing operation. Printed colors from the random sample size (n= 80) were measured against the General Requirement for the Applications in the Commercial Offset Lithography (GRACoL 2013) standards to derive the colorimetric/ densitometric values. Reference colorimetric values used in the analysis were the threshold deviations (acceptable color deviations) as outlined in the ISO12647-7 standards (GRACoL 2013). A control chart analysis was applied for further determining the process (CMDPW) ACD variation. The data collected were run through multiple software applications (Microsoft Excel/SPSS/Minitab) to apply various statistical methods. Analyzed data from the experiment revealed that the printed colorimetric values were in match (aligned) with the GRACoL 2013 (reference/target) standards. Since the color values were in control throughout the process, this enabled the CMDPW to produce consistent acceptable color deviation (average printed ΔE(2000) = 2.978). (The acceptable threshold color deviation is ΔE(2000) ≤ 3.00.) © 2023 The Author(s). This is an open access article published under a Creative Commons Attribution 4.0 International License (https://***/licenses/by/4.0).

关键词： Colorimetry

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A framework for realistic image synthesis 97

A framework for realistic image synthesis

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24th Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1997

作者： Greenberg, Donald P. Torrance, Kenneth E. Shirley, Peter Arvo, James Lafortune, Eric Ferwerda, James A. Walter, Bruce Trumbore, Ben Pattanaik, Sumanta Foo, Sing-Choong Program of Computer Graphics Cornell University 580 Frank H.T. Rhodes Hall Ithaca United States Department of Computer Science University of Utah United States Department of Computer Science California Institute of Technology United States Blue Sky Studios Harrison NY United States

ISBN: (纸本)0897918967

Our goal is to develop physically based lighting models and perceptually based rendering procedures for computer graphics that will produce synthetic images that are visually and measurably indistinguishable from real-world images. Fidelity of the physical simulation is of primary concern. Our research framework is subdivided into three sub-sections: the local light reflection model, the energy transport simulation, and the visual display algorithms. The first two subsections are physically based, and the last is perceptually based. We emphasize the comparisons between simulations and actual measurements, the difficulties encountered, and the need to utilize the vast amount of psychophysical research already conducted. Future research directions are enumerated. We hope that results of this research will help establish a more fundamental, scientific approach for future rendering algorithms. This presentation describes a chronology of past research in global illumination and how parts of our new system are currently being developed.

关键词： Light reflection

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Web-based course outcome assessment experience in computer engineering technology

Web-based course outcome assessment experience in computer e...

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114th Annual ASEE Conference and Exposition, 2007

作者： Rajaravivarma, Veeramuthu Baumann, Peter Central Connecticut State University United States Computer Electronics and Graphics Technology Department Central Connecticut State University New Britain CT United States Program Coordinator of Computer Engineer Technology IEEE-Connecticut Section United States Department of Engineering CCSU

In November 2004 an innovative undergraduate computer Engineering Technology program based on TAC of ABET program assessment criteria was granted licensure by the State Department of Higher Education. The University has considerable experience with accreditation and associated assessment activities, most recently reporting on an "Incommon Methodology for Objective- and Outcome-based programs Assessment" (Lema, L.F., Baumann, P.F., and Prusak, Z., ASEE 2005 Annual Conference) across three engineering technology programs. This study reports an assessment component within the computer Engineering Technology program in accordance with ABET accreditation criteria. The implementation process was conducted in an undergraduate course in the program. The initial phase involves identification of course goals, and based on these goals, the measurable learning outcomes are formulated. Using web-based methodology and course management tools such as WebCT or Vista, the learning outcomes are measured in the form of pre- and post-course survey data from students. Data can be imported to data management tools such as Excel for analysis and evaluation. This study uses computer programs as tools to facilitate data collection and data analysis, making the data intensive portion of the assessment and evaluation process an easier endeavor. Applicability towards the assessment efforts of other engineering technology programs is also addressed. © American Society for Engineering Education, 2007.

关键词： E-learning

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Dynamic simulation of non-penetrating flexible bodies 92

Dynamic simulation of non-penetrating flexible bodies

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Proceedings of the 19th annual conference on computer graphics and interactive techniques

作者： David Baraff Andrew Witkin Program of Computer Graphics Cornell University Ithaca NY School of Computer Science Carnegie Mellon University Pittsburgh PA

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Functional difference predictors (FDPs): measuring meaningful image differences

Functional difference predictors (FDPs): measuring meaningfu...

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Asilomar Conference on Signals, Systems & computers

作者： J.A. Ferwerda F. Pellacini Program of Computer Graphics Cornell University Pixar Animation Studios Emeryville Emeryville CA USA

In this paper we introduce functional difference predictors (FDPs), a new class of perceptually-based image difference metrics that predict how image errors affect the ability to perform visual tasks using the images. To define the properties of FDPs, we conduct a psychophysical experiment that focuses on two visual tasks: spatial layout and material estimation. In the experiment we introduce errors in the positions and contrasts of objects reflected in glossy surfaces and ask subjects to make layout and material judgments. The results indicate that layout estimation depends only on positional errors in the reflections and material estimation depends only on contrast errors. These results suggest that in many task contexts, large visible image errors may be tolerated without loss in task performance, and that FDPs may be better predictors of the relationship between errors and performance than current visible difference predictors (VDPs).

关键词： Reflection Rendering (computer graphics) computer graphics computer errors Pixel Performance evaluation Conducting materials Performance loss Layout Animation

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Assembly Maintainability Study with Motion Planning

Assembly Maintainability Study with Motion Planning

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Hsuan Chang Tsai-Yen Li Computer Graphics & Systems Program GE Corporate Research and Development Center Schenectady NY USA

ISBN: (纸本)0780319656

Maintainability is an important issue in design where the accessibility of certain parts is determined for routine maintenance. In the past its study has been largely manual and labor intensive. Either by using physical mockup or computer animation with CAD models of a design, the task relies on a human to provide an access path for the part. In this paper, the authors present an automated approach to replace this manual process. By applying results from and developing extensions to research in motion planning and other fields, the authors demonstrate that an automated maintainability study system is feasible. The authors describe general extensions needed to adapt robotic motion planning techniques in maintainability studies. The authors show results from applying such a system to two classes of industrial application problems.

关键词： Assembly Force sensors Fingers Animation Application software Tendons Grasping Motion control computer graphics Research and development

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Real-time robot motion planning using rasterizing computer graphics hardware 90

Real-time robot motion planning using rasterizing computer g...

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Proceedings of the 17th annual conference on computer graphics and interactive techniques

作者： Jed Lengyel Mark Reichert Bruce R. Donald Donald P. Greenberg Graduate Student Program of Computer Graphics Cornell University Ithaca N.Y. Assistant Professor and Director Computer Science Robotics Laboratory Department of Computer Science 4130 Upson HalI Cornell University Ithaca N.Y. Director Program of Computer Graphics Jacob Gould Shurman Professor of Computer Graphics Cornell University Ithaca N.Y.

ISBN: (纸本)9780897913447

We present a real-time robot motion planner that is fast and complete to a resolution. The technique is guaranteed to find a path if one exists at the resolution, and all paths returned are safe. The planner can handle any polyhedral geometry of robot and obstacles, including disjoint and highly concave unions of *** planner uses standard graphics hardware to rasterize configuration space obstacles into a series of bitmap slices, and then uses dynamic programming to create a navigation function (a discrete vector-valued function) and to calculate paths in this rasterized space. The motion paths which the planner produces are minimal with respect to an L1 (Manhattan) distance metric that includes rotation as well as *** examples are shown illustrating the competence of the planner at generating planar rotational and translational plans for complex two and three dimensional robots. Dynamic motion sequences, including complicated and non-obvious backtracking solutions, can be executed in real time.

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