最新刊期
卷 15 ， 期 6 ， 2010
- 摘要：This paper is the 15th of the literature bibliography on computer graphics engineering in China in 2009. We collected and classified most of the important papers in computer graphics field published in Chinese， selected references from 11 important Chinese journals published in 2009 and classified these references into different categories according to their contents. Based on the overview and analysis work， we found that the number of researchers and developers engaged in computer graphics-related field has been greatly increasing in the past 15 years， and many conferences are held each year， many high-level achievements are made in China. In addition， computer graphics develops itself， deriving out some new research topics or directions including cross disciplines.关键词：graphics engineering;graphics processing;computer graphics;survey3362|278|0更新时间：2024-05-08
- 摘要：Usually， the Region of Interest(ROI) video coding algorithm is implemented by using a smaller quantization parameter(QP) or more bit-plane inside ROI. It caused the degradation of quality by the artifacts of boundary and additional bit-rate burden in ROI. This paper proposes the grid quantization algorithm to avoid these disadvantages. The macroblocks inside of ROI are divided into three kinds: Grid A， Grid B and Gradient. Different partition has different quantization parameter based on visual masking effect. The test results show that the proposed algorithm can promote the ROI objective quality about 1.9dB on average， and the subjective quality is also improved obviously. Compared to other ROI quantization algorithm， the ROI quality is improved by 0.47dB， while the whole picture quality is improved by 0.625dB. The proposed algorithm can reduce the bit-rate burden of ROI and maintain subjective quality.关键词：masking effects;video coding;region-of-interest;quantization3944|222|0更新时间：2024-05-08
- 摘要：Median filter is widely used to denoise salt-and-pepper noise in image processing. But median filter can not preserving edges and most details of images， so median filter is not able to produce a satisfying result especially when edges and details are strictly requested to preserve. This paper introduces a new method for denoising salt-and-pepper noise with edge-preserving to resolve the problems existing in median filter. This method is a modified model of Statistical Jump Regression Analysis， and also modifies the energy function from L2 to L1. The experiment shows that this method can powerfully denoise salt-and-pepper noise with good edge-preserving.关键词：salt-and-pepper;median filter;statistical jump regression analysis;edge-preserving;L15477|213|0更新时间：2024-05-08
- 摘要：This paper presents a new active shape models(ASMs) based method to segment the prostate from CT images for the radiotherapy. The key point of ASMs is the construction of both shape model and appearance model. We utilize the scale invariant feature transform(SIFT) local descriptor， which is more distinctive than general intensity and gradient features on the edges of the prostate boundary in the CT images， to characterize the image features and build the appearance model. To accurately capture prostate shape variation， an online training mechanism is proposed to build the shape model. When the samples of current patient are limited， the population statistics is used to build the shape model. As the increase of the samples of current patient， the patient-specific statistics plays an important role for constructing the shape model gradually. We test our method on a data set including 264 images of 24 patients， the average Dice similarity coefficient (DSC) is 90.5% and the mean average surface distance(ASD) is 1.90mm. The results show that the proposed method is robust and accurate.关键词：active shape model;shape model;appearance model;prostate CT images;SIFT3629|247|0更新时间：2024-05-08
- 摘要：Script identification is significant for attaining information from document images. Most algorithms on texture feature extraction from document images for script identification are inadaptable to the skew of text line presently. For the skew of text line is inevitably， a new algorithm robust to the skew of text line is proposed. Steerable Pyramid transform is used on the document images and the energy statistical features of sub-bands is extracted. Through the realignment of features， the algorithm implements robustness to rotation. Libsvm is used as a classifier. The experiments are conducted on image database containing ten scripts that are scanned from books or magazines. The test samples are rotated with different angles and the results confirm that the algorithm can identify scripts accurately and is robust to the skew of text line simultaneously.关键词：script identification;Steerable Pyramid transform;texture feature;document images3334|222|0更新时间：2024-05-08
- 摘要：Multiple scattering and backward scattering on rough surface is caused by surface roughness and mirror effect， and this affects the precision of shape from shading arithmetic accordingly. This paper reconstructs the reflection map equation by using a bidirectional reflectance distribution function and the Hapke model. After the equation discretization， we calculated tilt and slant of the lighting and the surface， then get the height gradient of the lighting and the surface， recover the height data with a total differentiation method. The comparison of reconstruction of real cutting surface and the measured stylus profile result shows this algorithm is accurate and effective， and it inspires new thinking ways for the shape from shading of metal cutting surface for cutting surfaces.关键词：computer vision;surface micro-topography;lighting estimation;Hapke model;bidirectional reflectance distribution function3094|216|0更新时间：2024-05-08
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Inter-concepts Association and Dependency Multi-label Video Semantic Concept Classification Approach
摘要：In video data， one concept in one shot are usually dependent on others concepts. Several semantic concepts appearing in one time often determine the presence of other concepts. An inter-concepts association and dependency multi-label video semantic concept classification approach is proposed in this paper. In order to generate association and dependency relation between concepts， join and prune phases are used to extract potential itemsets. After calculating the minimum support of each itemset， frequency itemsets meeting the user specified minimum support are selected. In the iteration process of generation frequency itemsets， compound labels with strong association and dependency relation of inter-concepts are obtained. Finally， compound labels are considered as a single label in the annotation step. Experiments on real-world multi-label media data show that this method the methods beat accuracy of existing multi-label learning methods with statistically significant improvements.关键词：video concept annotation;multi-label classification;association relation;semantic scene classification2985|176|0更新时间：2024-05-08 - 摘要：Ground collapse was a typical geological disaster in karstic area. Comparing to other geological disaster， ground collapses were considerably small in scale and dispersive in distribution. This made detecting and identification of ground collapse in urban areas quite a challenging work. In this paper， an object-based image analysis method was used to detect the ground collapse sites using remote sensing images. Firstly， multi-scale image segmentation was performed on the 0.2 meter aerial image of study area and over tens of spatial， spectral， shape and texture features were extracted based on the segmented image objects. Then eight optimized features for ground collapse classification was selected using generic algorithm(GA)， which obtains the best fitness value in ground collapse classification. After that， some on the spot ground collapses were used as cases sites and cased-based-reasoning(CBR) classification was applied on all the segmented image objects， from large scale to small scale. In the end， classification accuracy was evaluated over the whole study area. The overall object-based CBR classification of ground collapse area is about 0.881 and the kappa coefficient is 0.791. Higher accuracy(0.889) is achieved for the ripe ground collapses detection. The same case library was also applied to another trial area for reusability testing and achieved satisfactory results. In conclusion， CBR method could be successfully applied to ground collapses detection using high resolution images. CBR method proposed in this paper could achieve betters classification accuracy than traditional supervised classification methods.3472|260|0更新时间：2024-05-08
- 摘要：The inherent speckle noise of SAR image affects the interpretation and the further processing，so it is important to suppress speckle noise of SAR images. A nice speckle filter would be preserving details while suppressing the noise. But now none of the existent filters can solve this problem ideally. TV-PDE(Total Variation Partial Differential Equation) was introduced to denoise speckle noise because is important to reduce the speckles for SAR image. The mathematical model for denoise was built and then the capability of this model was analyzed and also the importance of selecting preference. Experiments proved the validity of the model. Taking Peak Signal-to-Noise Ratio(PSNR) as criterion the best preference was found by using polynomial fitting. The model preserved the edge when denoise the speckle better comparing with other algorithms according to EPI(Edge Preserved Index).关键词：speckle noise;total variation(TV);partial differential equation(PDE);peak signal-to-noise ratio(PSNR);edge preserved index(EPI)3254|211|0更新时间：2024-05-08
- 摘要：Traditional dual graph modeling turn delays at road intersections are ill-suited to the time-dependent route planning in the travel information services, due to the ignorance of time-dependency of transportation networks. With introducing a time factor into a dual graph, a dynamic dual network model is presented, where the links in the original network are mapped into the nodes in the dual network, and the turns in the original network are mapped into the links in the dual network. Besides, the First-In-First-Out(FIFO) condition is defined for this dynamic dual network, and two relevant arrival-time computational formulas are then given out. The classical label-setting shortest path algorithm is temporally adapted to the dynamic dual network by the definition of origin-destination dual node sets and time-dependent dual node labels. An experiment on a real road network shows that the proposed model is suitable for dealing with the turn delays, and saved about 16 percent travel time in the real-time route planning.关键词：turn delay;dynamic dual graph;FIFO condition;route planning;shortest path3610|225|0更新时间：2024-05-08
- 摘要：In traditional CA, general transfer rule and same speed are used to drive models. In this kind of CA, spatial-temp differences of geographical phenomenon, both transfer rules and transfer speed, are ignored. To solve this problem, a partitioned & asynchronous CA based on spatial data mining is given in this paper. In this model, cell space is departed by dual-constraint spatial cluster and general transfer rule is replaced by partition transfer rule, asynchronous transfer speed is calculated using general grid and synchronous transfer speed is replaced by asynchronous transfer speed. Spatial differences of geographical transfer rule and geographical transfer speed are taken into account in this kind of models. Taking land use change in Hangzhou as a case, partitioned & asynchronous CA based on spatial data mining are implemented in land use. Result shows：comparing with traditional CA, partitioned & asynchronous CA based on spatial data mining can get more accurate simulation result, and this kind of models can be used to simulate geographical phenomenon in a larger area for a comparatively longer time. A new viewpoint of GeoCA is given in partitioned & asynchronous CA. In this kind of Model, spatial differences and temporal diversities are taken account into GeoCA, it makes simulations with this kind of model much closer to actuality. Yet theories and methods of partitioned & asynchronous CA is still in tentative research stage, there are many problems, such as divided methods of cell space, methods of calculating weight of dual-constraint spatial cluster, calculation of cell transfer speed, getting of transfer rules, evaluation of CA result accuracy, and applications of partitioned & asynchronous CA in simulating land use at larger area and during longer time and etc. should be discussed and analyzed.关键词：CA;spatial data mining;partition;asynchronous3479|214|0更新时间：2024-05-08
- 摘要：Image completion has attracted many researchers these years. The goal of image completion is to repair missing region of images, or to remove objects from images and fill the holes using background information, making it hard to distinguish by eyes. However, to repair huge structure is difficult. We divide the process of image completion into two parts. When the user specified the missing region and structure curves, we first define a global energy function; dynamic programming and belief propagation is used to decide the global minimal cost. This step is also called structure propagation and when it is completed, we scan the region left and implement texture synthesis. For the pixels on boundaries we use exemplar-based algorithm to copy and paste by patch; for the pixels inside the region, we employ a fast weighted Ashikhmin-WL algorithm. At last, the completed image is obtained. We construct a fast structural image completion system and get some results. Experimental results show that our algorithm is useful. Our algorithm will also be extended to video completion in the near future.关键词：image completion;structure propagation;texture synthesis;exemplar-based algorithm4099|191|0更新时间：2024-05-08
- 摘要：Due to the popularity of optical motion capture system, more realistic human motion data can be acquired easily and widely used in various applications such as video games, animation films, sports simulation and virtual reality. This paper proposes a framework and algorithm for 3D human motion synthesis based on nonlinear manifold learning. In this framework, high-dimensional motion samples are mapped into low-dimensional manifold, with nonlinear dimensionality reduction method, to the intrinsic representation of motion semantic features. Furthermore, the sample which is generated by user interactions in low-dimensional manifold can be reconstructed to obtain a 3D motion sequence which owns a new motion semantic feature by reverse mapping. The experimental results show that the method proposed in this paper can not only precisely control the physical features of motions(such as the location of a specific joint), but also can be used to synthesize new motion data which owns abstract motion semantic, such as motion styles.关键词：Manifold learning;motion synthesis;motion semantic feature3890|212|0更新时间：2024-05-08
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Automatic Image Annotation Using Social Group Latent Topic Mining and Multi-group Information Fusion
摘要：At photo sharing websites like Flickr, a lot of images can not be effectively used and retrieved due to lack of tags. In order to retrieve images effectively, this paper presents a novel social group latent topic mining and multi-group information fusion based automatic image annotation algorithm by exploiting the property that users in Flickr often recommend their uploaded pictures to associated social groups according to the hidden topics in each picture. Different from traditional automatic image annotation methods, this algorithm first adopts the latent Dirichlet allocation model to mine the latent topics in single social group and makes use of the hidden topics to filter initial noisy tags generated by tag propagation among similar images, then utilizes multi-group information fusion to generate the final annotations for images simultaneously belonging to multiple social groups. Experimental results show the effectiveness of this algorithm.关键词：automatic image annotation;social group;latent topic mining;latent Dirichlet allocation;multi-group information fusion3363|418|0更新时间：2024-05-08 - 摘要：Calibration of robot hand-eye generally needs to solve a rotation equation RaRx=RxRb. Many methods have been proposed, within which quaternion is the most concise one. But common methods using quaternion emphasize particularly on the application, and are short of relevant geometrical insight, and lack of comprehensive analysis of various solutions. In this paper we use quaternion geometry to solve the rotation equation, give proofs of solutions in various conditions in detail, and illuminate interesting insights between the analysis with quaternion matrix and the expression by geometry. Simulations have been tested. Analyzing solutions in various conditions and understanding the relevant geometrical meaning will help to ease the solving conditions and improve the performance of hand-eye calibration. Moreover, the study is important for the development of the quaternion geometrical analysis.关键词：hand-eye calibration;quaternion geometry;rotation equation;conditions3824|214|0更新时间：2024-05-08
- 摘要：In this paper we propose a vector-based hierarchical model for facial makeup’s expressions in Peking opera. First we analyze the drawing process of facial makeup in the traditional Peking opera, the shape features of patterns as well as the classification of patterns, and then build a vector pattern bank based on the hierarchical structure of patterns. According to the standards of facial action coding system (FACS), we decompose facial makeup into 40 key action units. During the synthesis process of the facial makeup, users only need to select patterns one by one from the pattern bank to compose needed facial makeup. By using free form deformation (FFD) technique, each expression of action units is obtained. In addition, users may have further control over facial expressions through editing tools provided in the system.关键词：Peking opera;expressions;hierarchic model;free form deformation3760|188|0更新时间：2024-05-08
- 摘要：A method to construct a 3D garment model from sketched contours is presented for interactive garment design of virtual characters. Our method has three features：firstly, a reference model of 3D mannequin is established by restricting the direction of the distance field along z-axis only, so that the computation of distance field is much easier; secondly, an efficient mapping from 2D sketch to 3D garment is established by using the relative position between sketched garment contour and the outline of human projection; thirdly, the 3D garment model is constructed according to the mapping between garment grids and the grids of human model, and it ensures that loose part of garments can be constructed correctly. The experiment results prove that the proposed method can generate the garment surface constrained by sketch and adapted the underlying form of character model, and the process can be performed in real time.关键词：sketchy contours;garment modeling;distance field;2D-3D mapping3119|386|0更新时间：2024-05-08
- 摘要：A group animation generation method based on machine learning was proposed in order to reduce the complexity of generating mass of similar but different natural human motions in group animations. There are two models. Poses learning model was built based on Gaussian process latent variable model to characterize a specific motion and dynamic model was built in latent space to characterize the dynamic evolving process of neighboring poses in latent space. These models can be represented as probability distribution over all poses composing the motion by learning from existing motion data. Dynamic prediction can be made in latent space for giving initial state, then hundreds of latent trajectories by Hybrid Monte Carlo sampling according to given probability distribution can be obtained. Group animations can be implemented by generating a series of similar but different natural motions reconstructed from these latent trajectories, thereby avoid the difficulty and complexity of calculating geometric relationship and physical constrains in inverse kinematics.关键词：machine learning;group animation;Gaussian process latent variable model;Gaussian process dynamic model3574|249|0更新时间：2024-05-08
- 摘要：Voronoi diagram(VD) is a very important geometry structure and an important research topic in computational geometry. It has been widely applied in computer graphics, GIS, machine engineering and robotics and so on. Incremental algorithm is one of the most popular algorithm to construct VD. To find the location of a new insertion site is a key problem and usually costs lots of time. Sweep-line algorithm can be seen as a special incremental algorithm, which spends O(nlog n) time to locate a insertion point. In this paper, an improved incremental algorithm for constructing the VD of a planar point set is presented. A new data structure named right convex hull chain is used to find the location of a new input site in O(nlog n) time. Compared with other incremental algorithms, this algorithm can also run in O(nlog n) time, but it’s simpler, more comprehensible and easier to implement.关键词：Voronoi diagram（VD）;Delaunay triangulation;incremental algorithm;sweep-line algorithm;right convex hull chain4479|203|0更新时间：2024-05-08
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