{"title":"Fast Equal-Area Mapping of the (Hemi)Sphere using SIMD","authors":"Petrik Clarberg","doi":"10.1080/2151237X.2008.10129263","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129263","url":null,"abstract":"We present a fast vectorized implementation of a transform that maps points in the unit square to the surface of the sphere, while preserving fractional area. The mapping uses the octahedral map combined with an equal-area parameterization and has many desirable features such as low distortion, straightforward interpolation, and fast inverse and forward transforms. Our SIMD implementation completely avoids branching and uses polynomial approximations for the trigonometric operations, as well as other tricks. This results in up to 9 times speed-up over a traditional scalar implementation. Source code is available online.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"27 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":"124958126","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":"A Shadow-Volume Algorithm for Opaque and Transparent Nonmanifold Casters","authors":"Byungmoon Kim, Kihwan Kim, Greg Turk","doi":"10.1080/2151237X.2008.10129262","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129262","url":null,"abstract":"Since precise shadows can be generated in real time, graphics applications often use the shadow-volume algorithm. This algorithm was limited to manifold casters but has been recently extended to general nonmanifold casters with oriented triangles. We provide a further extension to general nonmanifold meshes and an additional extension to shadows of transparent casters. To achieve these, we first introduce a generalization of an object's silhouette to nonmanifold meshes. By using this generalization, we can compute the number of caster surfaces between the light and receiver, and furthermore, we can compute the light intensity arriving at the receiver fragments after the light has traveled through multiple colored transparent receiver surfaces. By using these extensions, shadows can be generated from transparent casters that have constant color and opacity.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"54 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":"127940115","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 Curve Fitting","authors":"Sarah F. Frisken","doi":"10.1080/2151237X.2008.10129260","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129260","url":null,"abstract":"We propose a method for fitting a piecewise parametric curve to a sequence of digitized points such as those acquired from a computer mouse or digitizing pen. The fitting is done on-the-fly rather than after a complete sequence of points has been acquired, thereby providing high-quality parameterized curves for immediate display during drawing. The method is fast, accurate, and robust, handles complex input paths, maintains corners, and ensures at least G 1 continuity at non-corner points. The method uses vector distance fields, which we describe here, to represent the intended input path of the digitized points in order to achieve its quality and performance. Detailed pseudocode is available online.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"55 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":"133864269","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":"Calculating Center of Mass in an Unbounded 2D Environment","authors":"Linge Bai, D. Breen","doi":"10.1080/2151237X.2008.10129266","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129266","url":null,"abstract":"We study the behavior of simple, 2D, self-organizing primitives that interact and move in an unbounded environment to create aggregated shapes. Each primitive is represented by a disk and a unit point mass. In order to compare the aggregated shape produced by the primitives to other shapes, the centers of mass of the two shapes must be aligned. We present an algorithm for calculating the center of mass (COM) for a set of point masses that are distributed in an unbounded 2D environment. The algorithm calculates the centroid for each coordinate component separately by forming two \"orthogonal\" tubes, calculating a center of mass in 3D for each tube and then projecting the 3D COM back onto the tubes, in order to produce the 2D COM of the points.","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":"127329593","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":"Reducing Noise in Image-Space Caustics with Variable-Sized Splatting","authors":"Chris Wyman, C. Dachsbacher","doi":"10.1080/2151237X.2008.10129252","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129252","url":null,"abstract":"In this paper, we present improvements to the recently introduced technique of caustics mapping, which allows for interactive hardware-accelerated rendering of caustics. These improvements reduce noise without completely eliminating the high-frequency details necessary for realistic caustics. When creating a basic caustics map, photons are emitted from the light in a regular grid pattern— each pixel in a rasterized image becomes a photon. However, photon convergence and divergence arising from reflections and refractions leads to oversampling and undersampling, as photons are no longer evenly distributed about the environment. Our improved techniques treat each photon as a variable-sized splat, allowing photon energy to be distributed over larger- or smaller-sized regions. Conceptually, these splats are similar to the variable-radius k-nearest neighbor search used in photon mapping, allowing noise reduction in areas of low photon density while maintaining crisp caustics at focal points. Our techniques improve image quality at a modest cost that is significantly cheaper than supersampling the photon buffer. Source code is available online.","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":"130358844","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":"Simple Empty-Space Removal for Interactive Volume Rendering","authors":"V. Vidal, Xing Mei, Philippe Decaudin","doi":"10.1080/2151237X.2008.10129258","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129258","url":null,"abstract":"Interactive volume rendering methods such as texture-based slicing techniques and ray casting have been well developed in recent years. The rendering performance is generally restricted by the volume size, the fill-rate, and the texture fetch speed of the graphics hardware. For most 3D data sets, a fraction of the volume is empty, which will reduce the rendering performance without specific optimization. In this paper, we present a simple kd-tree-based space partitioning scheme to efficiently remove the empty spaces from the volume data sets at the preprocessing stage. The splitting rule of the scheme is based on a simple yet effective cost function evaluated through a fast approximation of the bounding volume of the nonempty regions. The scheme culls a large number of empty voxels and encloses the remaining data with a small number of axis-aligned bounding boxes, which are then used for interactive rendering. The number of boxes is controlled by halting criteria. In addition to its simplicity, our scheme requires little preprocessing time and improves the rendering performance significantly.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"39 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":"127058715","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}
Louis Bavoil, Steven P. Callahan, Cláudio T. Silva
{"title":"Robust Soft Shadow Mapping with Backprojection and Depth Peeling","authors":"Louis Bavoil, Steven P. Callahan, Cláudio T. Silva","doi":"10.1080/2151237X.2008.10129254","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129254","url":null,"abstract":"Soft shadow mapping is an attractive solution to the problem of realtime soft shadows because it works with any kind of rasterizable geometry (in particular alpha-transparent textures and hair), it does not require any precomputation, and it is simple to implement on the GPU. However, state-of-the-art approaches have several limitations that prevent them from being practical for all scenes. First, parameter tuning is required to avoid surface acne. Second, gaps between shadowmap pixels are either ignored, which results in light bleeding, or handled using gap filling, which results in overshadowing. We present a more robust soft shadow mapping technique, based on a recent backprojection algorithm, that uses depth peeling to address the problems of surface acne and light bleeding. Our algorithm uses a multi-layer shadow map to reduce light bleeding, and midpoint shadow maps to handle self-shadowing more robustly. It provides high-quality soft shadowing for complex scenes, while still maintaining interactive rendering rates. Source code is available online.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"1 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":"126298460","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":"Query Sphere Indexing for Neighborhood Requests","authors":"N. Brodu","doi":"10.1080/2151237X.2008.10129265","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129265","url":null,"abstract":"This is an algorithm for finding neighbors for point objects that can freely move and have no predefined position. The query sphere consists of a center location and a given radius within which nearby objects must be found. Space is discretized in cubic cells. This algorithm introduces an indexing scheme that gives the list of all the cells making up the query sphere, for any radius and any center location. It can additionally take into account both cyclic and noncyclic regions of interest. Finding only the k-nearest neighbors naturally benefits from the query sphere indexing by running through the list of cells from the center in increasing distance and prematurely stopping when the k neighbors have been found. 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":"121682770","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 Rainfall","authors":"Pierre Rousseau, V. Jolivet, D. Ghazanfarpour","doi":"10.1080/2151237X.2008.10129270","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129270","url":null,"abstract":"Outdoor video games can improve their realism through weather effects simulation. However, simulating rain can yield many problems. We present solutions to address these problems and describe a complete framework to simulate rainfall in a video game. Rendering uses shaders to refract the scene inside the raindrops, based on optical properties. Retinal persistence is also considered. Animation is entirely conducted on graphics hardware, taking into account collisions and wind advection. An interface is presented, which allows the creation of complex wind fields by the user. Videos and shaders are available online.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"54 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":"121684390","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":"Versatile Decorative Halftoning","authors":"A. Hausner","doi":"10.1080/2151237X.2008.10129257","DOIUrl":"https://doi.org/10.1080/2151237X.2008.10129257","url":null,"abstract":"This paper describes a flexible tool for decorative halftoning. Decorative halftoning produces a picture that can be seen simultaneously on two levels: either as an overall image or as a grid of much smaller motif images. The tool presented here is flexible: any small image can be used as a motif. When the motif is a black-and-white image, this tool improves on other techniques, which cannot handle all such images: they are restricted to motif images that can be reduced to a skeleton of curved lines. Even for such images, the tool described here retains more spatial detail from the overall image.","PeriodicalId":318334,"journal":{"name":"Journal of Graphics Tools","volume":"42 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":"122482877","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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