{"title":"A Nonoriented, Nonmanifold Boundary Representation for Geometric Applications","authors":"Frutuoso G. M. Silva, A. Gomes","doi":"10.1080/2151237X.2008.10129264","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129264","url":null,"abstract":"Topology-based geometric models are important in many fields, including CAD (computer-aided design) and computer graphics. This paper introduces a general, concise, and responsive topology-based geometric data structure, called NNB-rep (nonoriented, nonmanifold boundary representation). Its generality comes from its ability to store manifold and nonmanifold geometric models, no matter whether they are degenerate or not, as needed in the first stages of the design and modeling of engineering artifacts, in particular those with cracks and degeneracies. Unlike most boundary models, the NNB-rep does not accommodate any topologically oriented cells, hence its compactness. Furthermore, despite the classical trade-off between memory and time performance, the NNB-rep is quite responsive because it hosts an optimal incidence scheme C 9 4, which makes it adequate for a number of interactive geometric applications.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128244118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enhanced Color-to-Gray Conversion","authors":"Martin Faust","doi":"10.1080/2151237X.2008.10129259","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129259","url":null,"abstract":"Important visual details are lost when a color image is converted into a luminance image using GIMP, Adobe Photoshop, or other graphic tools (see Figure 1). An enhanced conversion method is presented that creates an optimized grayscale image with visual artifacts of the standard method reduced to a minimum. The run time of the algorithm is linear in the number of pixels and allows a very simple implementation compared to other color-to-gray solutions.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129034379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Subtractive Shadows: A Flexible Framework for Shadow Level of Detail","authors":"Christopher DeCoro, S. Rusinkiewicz","doi":"10.1080/2151237X.2008.10129255","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129255","url":null,"abstract":"We explore the implications of reversing the process of shadow computation for real-time applications that model complex reflectance and lighting (such as that specified by an environment map). Instead of adding illumination contributions at each pixel across various lights, we compute the complete, unshadowed local illumination at each pixel using approximations, then subtract the lighting contribution from each light for which the pixel is in shadow. This provides flexible level of detail for shadow computation in ways that standard additive shadows do not, such as permitting the use of fast methods for accurate direct illumination combined with a small number of shadow-casting lights, and allowing for downsampled shadows to reduce fill cost. This technique preserves that portion of the scene with the greatest visual importance—the direct illumination—and allows shadows to be presented with lower fidelity in exchange for improvements in speed. With subtractive shadows, we are able to interactively manipulate and render arbitrary BRDFs and environment maps applied to complex, dynamic scenes with shadows, achieving in real time effects that previously required offline computation or preprocessing.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114535234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Efficient GPU-Based Texture Interpolation using Uniform B-Splines","authors":"D. Ruijters, B. H. Romeny, P. Suetens","doi":"10.1080/2151237X.2008.10129269","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129269","url":null,"abstract":"This article presents uniform B-spline interpolation, completely contained on the graphics processing unit (GPU). This implies that the CPU does not need to compute any lookup tables or B-spline basis functions. The cubic interpolation can be decomposed into several linear interpolations [Sigg and Hadwiger 05], which are hard-wired on the GPU and therefore very fast. Here it is demonstrated that the cubic B-spline basis function can be evaluated in a short piece of GPU code without any conditional statements. Source code is available online.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134545686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Efficient Ellipsoid-OBB Intersection Test","authors":"T. Larsson","doi":"10.1080/2151237X.2008.10129253","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129253","url":null,"abstract":"An efficient algorithm to determine the intersection status between arbitrarily oriented ellipsoids and boxes (OBBs) is presented. By choosing a proper representation of the geometric objects and by utilizing an affine transformation of space, the problem is converted into a corresponding sphere-parallelepiped intersection test. Thereby, the evaluation of more costly mathematical operations other than a constant number of simple arithmetic operations and comparisons can be avoided. Further efficiency is also gained by exploiting the regularity of the involved geometric shapes, as well as early rejection tests. Practical experiments show a four-times speed-up on average when these techniques are used.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123736780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Efficient, High-Quality Bayer Demosaic Filtering on GPUs","authors":"M. McGuire","doi":"10.1080/2151237X.2008.10129267","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129267","url":null,"abstract":"This paper describes a series of optimizations for implementing the high-quality Malvar-He-Cutler Bayer demosaicing filter on a GPU in OpenGL. Applying this filter is the first step in most video-processing pipelines but is generally considered too slow for real time on a CPU. The optimized implementation contains 66% fewer ALU operations than a direct GPU implementation and can filter 40 simultaneous HD 1080p video streams at 30 fps (2728 Mpix/s) on current hardware. It is two to three times faster than a straightforward GPU implementation of the same algorithm on many GPUs. Most of the optimizations are applicable to other kinds of processors that support SIMD instructions, like CPUs and DSPs. Source code is available online.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"93 3 Suppl 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128459896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Elena Jakubiak Hutchinson, Sarah F. Frisken, R. N. Perry
{"title":"Proximity Cluster Trees","authors":"Elena Jakubiak Hutchinson, Sarah F. Frisken, R. N. Perry","doi":"10.1080/2151237X.2008.10129256","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129256","url":null,"abstract":"Hierarchical spatial data structures provide a means for organizing data for efficient processing. Most spatial data structures are optimized for performing queries, such as intersection and containment testing, on large data sets. Set-up time and complexity of these structures can limit their value for small data sets, an often overlooked yet important category in geometric processing. We present a new hierarchical spatial data structure, dubbed a proximity cluster tree, which is particularly effective on small data sets. Proximity cluster trees are simple to implement, require minimal construction overhead, and are structured for fast distance-based queries. Proximity cluster trees were tested on randomly generated sets of 2D Bézier curves and on a text-rendering application requiring minimum-distance queries to 2D glyph outlines. Although proximity cluster trees were tailored for small data sets, empirical tests show that they also perform well on large data sets.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133673676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Line Clipping by Managing Polygon Edges in Convex Polylines","authors":"Wencheng Wang, Chunjuan Sun, Jing Li, E. Wu","doi":"10.1080/2151237X.2008.10129261","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129261","url":null,"abstract":"Existing algorithms for clipping line segments against a concave polygon always need to compute all edges, resulting in a time complexity O(n) for computing intersection points, where n is the number of edges of the clipping polygon. This paper presents a new algorithm that first separates polygon edges into convex polylines and then clips lines against them, where a convex polyline is a sequence of edges that can form a convex polygon by themselves. As a result, the time complexity for computing intersection points is reduced, varying adaptively between O(log n) and O(n), and is lower than O(n) in most cases. To further improve clipping efficiency the new algorithm is combined with an axis-aligned BSP tree that is used to manage convex polylines for quickly finding convex polylines that might intersect the clipped lines. Examples show that the new algorithm can be several times faster than existing algorithms for line clipping.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"50 1-5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132186830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"GPU Color Constancy","authors":"M. Ebner","doi":"10.1080/2151237X.2008.10129268","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129268","url":null,"abstract":"A sensor located inside a digital camera is only able to measure the light that is reflected by an object. The reflected light varies with the spectral power distribution of the illuminant. Hence, images taken with a digital camera may show a strong color cast if an incorrect white balance setting has been chosen. Such a color cast may also be due to an automatic white balance not working correctly. In contrast, colors perceived by a human observer appear to be approximately constant. Algorithms for automatic white balance try to mimic this ability and compute a color-corrected image that appears to have been taken under an illuminant with a uniform power distribution. I show how color-constancy algorithms can be implemented very efficiently on modern graphics processing units.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128468504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Continuous Cube Mapping","authors":"C. Grimm, Bill Niebruegge","doi":"10.1080/2151237X.2007.10129250","DOIUrl":"https://doi.org/10.1080/2151237X.2007.10129250","url":null,"abstract":"Existing environment-mapping techniques include spherical mapping and cube mapping. These techniques have inherent flaws that cause sampling issues and aliasing. Continuous cube mapping is offered as an alternative environment-mapping approach that effectively folds the cube onto the sphere, providing a better parameterization of cube mapping. We provide a hardware implementation. Source code is available online.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131029125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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