http://wiki.cs.purdue.edu/cgvlab/ 2012-05-08T05:15:03-04:00 http://wiki.cs.purdue.edu/cgvlab/ http://wiki.cs.purdue.edu/cgvlab/lib/images/favicon.ico text/html 2011-08-08T10:48:26-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:ae_compliancy&rev=1312814906&do=diff Summary A desired target appearance may not always be possible given an appearance editing setup. This leads to errors in the resulting appearance (e.g., color shifting) which can lead to potentially misleading visualizations. To achieve more compliant appearances, we modify either (or both) the projector placement or the target appearance (in progress). Luminance Compliancy for Virtual Restoration For our virtual restoration project, we considered luminance compliancy in order to ensure … text/html 2011-10-25T05:22:40-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:ae_resolution_enhancement&rev=1319534560&do=diff Summary The quality of an appearance edit is directly related to the resolution achievable by the projectors available. Various factors affect a projector's resolution and radiant power, including the projector's distance to the object and the orientation of the projector to the object. In this work, we analyze the appearance editing setup and projector pixel interaction to improve the quality of our appearance edits. Our projectors are set up such that their fields of projection are superimp… text/html 2010-08-05T12:10:00-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:appearance_editing&rev=1281024600&do=diff Summary Appearance editing offers a unique way to view visually altered objects with various appearances or visualizations. By carefully controlling how an object is illuminated using digital projectors, we obtain stereoscopic imagery for any number of observers with everything visible to the naked eye (i.e., no need for head-mounts or goggles). Such an ability is useful for various applications, including scientific visualization, virtual restoration of cultural heritage, and display systems… text/html 2008-09-15T21:35:04-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:cam_cad&rev=1221528904&do=diff Summary We are developing computer-aided mechanical design software in which all design tasks are performed within a single computational paradigm. Mechanical design is the task of devising an assembly of parts that performs a function reliably and economically. It is a ubiquitous activity that spans mechanical, electrical, and biomedical engineering. Designers need to devise, analyze, and compare competing design prototypes to produce optimal designs. Computer-aided design reduces design tim… text/html 2010-02-19T09:32:59-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:camera_model_design&rev=1266589979&do=diff Summary Images are used in computer graphics and visualization to convey information. Images are computed by sampling data with rays defined by a camera model. Most images used in computer graphics and visualization are computed using the planar pinhole camera model, which suffers from important limitations such as uniform sampling rate, and single viewpoint. We propose to overcome these limitations through camera model design. The camera model design paradigm advocates designing the set of r… text/html 2008-09-15T21:33:22-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:computational_geometry&rev=1221528802&do=diff Summary In conjunction with Victor Milenkovic (U. Miami), we are developing a theoretical model of robust computational geometry with floating point arithmetic. Computational geometry is the branch of theoretical computer science that develops efficient algorithms for geometric queries and constructions. This is a core research problem with numerous applications in science and in industry. The robustness problem is to implement geometric algorithms with computer arithmetic. Geometric algorith… text/html 2008-09-23T13:15:24-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:distance_learning&rev=1222190124&do=diff Summary More than half of the higher education institutions in the United States offer distance learning services, and the enrollment doubles every three years. Unfortunately, current distance learning systems fail to match the effectiveness of conventional on-campus learning. Remote students feel isolated because of low level of interactivity during remotely delivered lectures and because of lack of access to other proven on-campus learning activities such as office hours and study groups. … text/html 2010-02-22T15:03:14-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:general_pinhole_camera&rev=1266868994&do=diff Summary We introduce the general pinhole camera (GPC), defined by a center of projection (i.e. the pinhole), an image plane, and a set of sampling locations in the image plane. We demonstrate the advantages of the GPC in the contexts of remote visualization, of focus plus context visualization, and of extreme antialiasing, which benefit from the GPC sampling flexibility. For remote visualization we describe a GPC that allows zooming-in at the client without the need for transferring additiona… text/html 2012-05-01T10:35:52-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:genuinity&rev=1335882952&do=diff Summary This NSF-funded project seeks to provide methods to embed into a physical object information for a variety of purposes, including genuinity detection, tamper detection, and multiple appearance generation. Genuinity detection refers to encoding fragile or robust signatures so that a copy, or tampered, version can be differentiated from the original object. Multiple appearance generation refers to generalizing the encoded information from a signature to a different appearance of the same … text/html 2011-06-08T11:40:43-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:genuinitytemp&rev=1307547643&do=diff Summary This NSF-funded project seeks to provide methods to embed into a physical object information for a variety of purposes, including genuinity detection, tamper detection, and multiple appearance generation. Genuinity detection refers to encoding fragile or robust signatures so that a copy, or tampered, version can be differentiated from the original object. Multiple appearance generation refers to generalizing the encoded information from a signature to a different appearance of the same … text/html 2009-10-26T11:53:14-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:graphcamera&rev=1256572394&do=diff Summary The Graph Camera is a tool for generating multi-perspective views of a complex 3-D environment. The Graph Camera begins as a standard planar pinhole camera frustum. That frustum then undergoes a series of bending, splitting, and merging operations. The resulting images are mostly continuous and allow for comprehensive views of 3-D space. Bend Operation Split Operation Merge Operation Graph Camera Frustum Graph of Frusta Navigation One application of the Gra… text/html 2008-09-16T10:06:46-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:inter-reflections&rev=1221574006&do=diff Summary Modeling real-world scenes, beyond diffuse objects, plays an important role in computer graphics. One active approach is projecting binary patterns in order to obtain correspondence and reconstruct a densely sampled 3D model. In such structured-light systems, determining whether a pixel is directly illuminated by the projector is essential to decoding the patterns. When a scene has abundant indirect light, this process is especially difficult. We present a robust pixel classification … text/html 2008-09-15T21:34:10-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:massive_model_rendering&rev=1221528850&do=diff Summary Rendering and visualizing large 3D synthetic models is a crucial component of many engineering disciplines and is becoming increasingly more important for simulations, gaming, and education. Although rendering hardware continues to improve, the desire to render even larger models continues to increase. Historically, large models could only be rendered on highly specialized computers. However, today's PC are an attractive platform for interactive rendering as well. In the following wor… text/html 2008-09-19T13:36:41-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:model_camera&rev=1221845801&do=diff Summary The ModelCamera is a fast, easy to use, and inexpensive 3D scene modeling system. The ModelCamera acquires dense color (720×480 video frames) augmented with sparse depth (7×7 to 11×11 depth samples). The frames are registered and merged into an evolving model at the rate of five frames per second. The model is displayed continually to provide immediate operator feedback. Structured Scene Modeling Structured scenes (e.g. large pieces of furniture, walls, ceiling, and floor) are a… text/html 2008-09-15T21:29:28-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:mrt&rev=1221528568&do=diff Summary The first part of our effort is the development of the Mixed-Reality Tabletop (MRT). The MRT is a concept where a mentor and a remote mentee can simultaneously use the 'same' tabletop. This is accomplished through a camera capturing an image of the tabletop and sending it to the remote table, and a projector displaying the image received of the remote table. “Real” objects are defined as those that are physically located on the local table, and “virtual” objects are those located on… text/html 2010-03-10T10:03:42-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:npi&rev=1268233422&do=diff Summary It is a common approach to replace scene geometry with image based approximations for fast rendering effects. These approximations are usually generated using orthographic or perspective projections. We replace these traditional approximations with non-pinhole approximations in order to improve rendering quailty. By providing fast ray impostor intersection, we produce higher-quality results with similar performance to the traditional approach. Publications People text/html 2008-09-15T21:25:51-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:occlusion-resistant&rev=1221528351&do=diff Summary In this project, we propose a family of Occlusion-Resistant Camera (ORC) designs for acquiring active environments despite the presence of moving interfering occluders. Being able to capture images in an in-use environment increases acquisition efficiency and quality without having to close-off the targeted site. Our cameras explicitly remove interfering dynamic occluders from acquired data in real-time and during live capture. Our key idea is to capture the scene at least twice from … text/html 2009-08-26T15:27:01-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:occlusion_camera&rev=1251314821&do=diff Summary One advantage of image-based rendering is scene-independent rendering cost. However, rendering a scene with a single reference depth image produces disocclusion errors: samples are lacking for surfaces that are visible in the desired view, but not in the reference view. Even small view changes produce noticeable errors. We introduce occlusion cameras, a class of non-pinhole cameras whose rays reach around occluders to gather samples that are hidden in the reference view but are likely… text/html 2008-09-15T21:33:43-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:path_planning&rev=1221528823&do=diff Summary This work develops path planning algorithms for a polyhedral robot and static obstacles . Path planning is important for robot navigation and manipulation, design for assembly, virtual prototyping, and computer graphics. Although complete planning algorithms are available, they have proved impractical. The most successful technique to date is probabilistic planning. The drawback is that there is no efficient way to select enough samples to guarantee a specified success rate. Picking a… text/html 2008-09-15T21:28:46-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:perception&rev=1221528526&do=diff Summary We have conducted two psychophysical experiments that compare shape perception between a volumetric 3D display and an LCD display. Our 3D display is a device that renders a 3D image by displaying, in rapid succession, radial slices through the scene on a rotating screen. The image is contained in a glass globe and can be viewed from virtually any direction. Experiment 1 In one experiment objects with varying complexity were used as stimuli. On each trial an object or a distorte… text/html 2011-06-08T11:37:50-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:photogeometric&rev=1307547470&do=diff Summary We present a new photogeometric framework for acquiring highly-detailed models of 3D objects and using these models for enabling interactive and close-up digital inspection. Our framework meets design goals of being fast, robust, and easy-to-use. Further, our framework demonstrates a setup of off-the shelf digital projectors and cameras, without any prior calibration, that enables a trade-off from coarse acquisitions to highly-detailed and optimized models. A key inspiration for our f… text/html 2008-09-15T21:28:14-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:reflected_impostors&rev=1221528494&do=diff Overview The sample-based camera (SBC) is a method for rendering curved reflectors based on projecting reflected vertices. The SBC is a set of BSP trees with simple cameras at their leafs. When the reflector geometry is complex, the viewing volumes of the simple cameras intersect and they cannot be efficiently separated by the BSP tree, which leads to inefficient projection. In order to support complex reflectors we developed a reflection rendering technique based on simplifying the reflecte… text/html 2010-10-12T13:16:56-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:reflections&rev=1286903816&do=diff Summary This project is concerned with developing techniques which producing high-quality rendering effects such as reflections, refractions, ambient occlusion, and relief texture mapping at interactive rates. This is done one of two ways. The first, develop cameras based upon a object in the scene and render the scene using those cameras. Alternatively, we replace geometry with images generated by non-pinhole cameras. Rays can then be intersected with the image-based approximations of the ge… text/html 2008-09-15T21:23:24-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:repetitive_motion&rev=1221528204&do=diff Summary Obtaining models of dynamic 3D objects is an important part of content generation for computer graphics. If the states or poses of the dynamic object repeat often during a sequence (but not necessarily periodically), we call such a repetitive motion. Our key observation is that for repetitive motions we can use one fixed camera to perform robust motion analysis and a second capture-device to provide 3D information of each motion state. After the motion sequence, we group temporally di… text/html 2009-11-16T11:21:17-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:sample_camera&rev=1258388477&do=diff Feed-forward reflection rendering The sample-based camera (SBC) is a general camera constructed from a given set of rays. The first application of SBCs that we have explored is rendering accurate reflections on curved reflectors at interactive rates. In order to render reflections with the feed forward graphics pipeline, one has to compute the image points where a reflected scene point projects. For general reflectors, the problem of projecting reflected vertices does not have a closed form s… text/html 2008-09-15T21:26:19-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:sea_of_images&rev=1221528379&do=diff Summary Visual simulation of large real-world environments is one of the grand challenges of computer graphics. Applications include remote education, virtual heritage, specialist training, electronic commerce, and entertainment. In this project, we present a “Sea of Images,” an image-based approach to providing interactive and photorealistic walkthroughs of complex indoor environments. Our strategy is to obtain a dense sampling of viewpoints in a large static environment with omnidirectional … text/html 2009-03-04T11:25:57-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:simplify_reconstruction&rev=1236183957&do=diff Summary Reconstructing large models from images is a significant challenge for computer graphics, computer vision, and related fields. In this project, we investigate an approach for simplifying the reconstruction process by mathematically eliminating external camera parameters. This results in less parameters to estimate and in an overall significantly more robust and accurate reconstruction. Unlike self-calibration, omitting pose parameters from the acquisition process implies no external c… text/html 2008-09-15T21:35:53-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:spatial_geometric_constraints&rev=1221528953&do=diff Summary This work is joint with Prof. Sitharam at the University of Florida. The major focus of the work is to advance the state of the art in geometric constraint solving, especially spatial constraint solving. Key results of the work include an efficient general purpose decomposition algorithm for large-scale constraint problems, and many new techniques for solving nonlinear algebraic equation systems that arise in the decomposition. The work also includes the development of a 3D sketcher t… text/html 2011-10-18T16:16:55-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:urban&rev=1318969015&do=diff Internal New website A new website of the urban modeling and visualization projects at Purdue is available here. Publications People text/html 2010-07-24T00:05:58-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:virtual_restoration&rev=1279944358&do=diff Summary We present a system to virtually restore damaged or historically significant objects without needing to physically change the object in any way. This work addresses both creating a restored synthetic version of the image as viewed from a camera and projecting the appropriate light patterns using digital projectors to give the illusion of the object being restored. The restoration algorithm minimizes an energy metric which enforces a set of contour criteria over the surface of the obje… text/html 2009-03-05T17:23:22-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:virtual_restoration_of_real-world_objects&rev=1236291802&do=diff Summary We present a system to virtually restore damaged or historically significant objects without needing to physically change the object in any way. This work addresses both creating a restored synthetic version of the image as viewed from a camera and projecting the appropriate light patterns using digital projectors to give the illusion of the object being restored. The restoration algorithm minimizes an energy metric which enforces a set of contour criteria over the surface of the obje… text/html 2008-09-15T21:32:52-04:00 http://wiki.cs.purdue.edu/cgvlab/doku.php?id=projects:visualization_large-scale_simulations&rev=1221528772&do=diff Summary The goal of our team was to produce a visualization of the September 11, 2001 attacks on the Pentagon and World Trade Center. The immediate motivation for the project was to understand the behavior of the building under the impact. The longer term motivation was to establish a path for producing high-quality visualizations of large scale simulations. The first challenge was managing the enormous complexity of the scene to fit within the limits of state-of-the art simulation software s…