最新刊期
卷 7 ， 期 6 ， 2002
- 摘要：This paper is the literature bibliography on computer graphics in China in 2001. Graphics engineering is an inter-subject on studying graphical theory, graphical techniques and graphical application. Its research content covers almost all aspects of the human life, including industry, visualization, education, entertainment, et al. In the early beginning of 1990's, some new graphics techniques are derived from traditional computer graphics, they are virtual reality, visualization, physical based simulation. Based on the current status of the research on graphics engineering as well as the distribution of related publications in China, we began this literature overview work from 1996, we collected and classified most of important papers in computer graphics field in every year,selecting 290 references from 11 important Chinese journals published in 2001 and classified these references into different categories according to their contents. We hope that the paper could provide readers with a general and up-to-date overview of graphics engineering in China.2831|495|0更新时间：2024-05-07
- 摘要：The analysis of research status for based-constraint parametric design is given. This article gives main limitations for early CAD system firstly, then reviews the development process of parametric design by main features in different phases. Parametric design methods are divided into program parametric design, on-line alternating parametric design and off-line parametric design. The principles and features are given for primary method, variational geometry method, artificial intelligence method and constructional process method, in the same time, some representative methods, such as geometry reasoning based on knowledge, constraint promulgation based on freedom analytical, are introduced in artificial intelligence method. Main processes and features for off-line parametric design are given. In the end, the article analyzes the current research situation, problems in different parametric methods and research direction in the future work.2642|475|0更新时间：2024-05-07
- 摘要：The image transformation coding is classified into two categories:one-dimension transformation coding and two-dimension transformation coding. One-dimension transformation coding need little computation, proceeds fast, but its effect is dependent on the image scanning techniques. The central problem of the image scanning techniques is how to decrease the undulation of the generated data. In this paper, based on the deep researches, and objective quantity exponent is defined to measure the undulation of the scanning techniques. By it, with the help of computer experiments, it is proved that the Hilbert scanning technique is superior to the other scanning techniques and the data it generates is the most continuous based on the hypothesis that the images are continuous in the small range. The effect to the DCT coding of the scanning techniques is analyzed by computer experiments. Finally, a fast recurrent algorithm to construct the Hilbert scanning matrixes is given out for easy to use this scanning technique to code the images and to go on more researches.2955|411|0更新时间：2024-05-07
- 摘要：Corner detection is an important task in various computer vision and image-understanding system. Traditional methods are based on chain-code and curvature computation of curves, which suffer the dependence either on the correctness of region segmentation or on the susceptivity of noise. In this paper, a novel corner detection method based on mathematical morphology is proposed, which is very different from traditional chain-code based corner detection methods. This method is based on morphological skeleton principle, and uses a modified opening operator to detect the convex and concave corner of the image. The result of the corner detection is achieved by compose the result of the two-corner sets of the source image and its complement set. The multi-scale morphological filter is used to eliminate noise. The uniform model of corner detection has also been established. Experiments show that this method leads to accurate detection, low computational cost, and rotational invariance.2783|412|0更新时间：2024-05-07
- 摘要：The degenerate illumination model for the optics camera system is introduced, and a fast method for gray-level correction is presented. It needn't additional parameters and mathematic model, only performs on the image. It corrects degenerate illumination based on the strategy of original image subtraction from background image. Generally say, the method includes three steps: first, background subset extraction. The image is divided into blocks, then according to the image characteristic, one point is extracted as the background point for each block; second, the whole background building. The whole background image can be got by interpolation from the background subset extracted in previous step; then the last step is correction using subtract the background image from original image This method can not only keep the object of original image, but also be efficacious, fast and simple. It has proved good result from the crack detection of surface of highway.2712|401|0更新时间：2024-05-07
- 摘要：The presence of the difference of the gray value and the distortion between the object image and the reference image is inevitable, traditional matching method will tend to be degraded by the noise and the occlusion because that every pixel in the image will do equal contribution to the matching result. From another viewpoint, this paper proposed a new image matching method based on a novel distance measurement. It counts not the distance of the gray level of the two images, but the number of the pixels in the object image which are close to the pixels in the reference image. Then applied the measurement method to the process of the image matching. The correlation curve got in this way is much more sharp. So the image matching method has high match precision. And in the procces of the tracking, there must be many change in the object image, then the resonable updation of the reference image will be the key of the tracking problem.On the basis of the similarity measurement, a suitable template updating strategy is presented. The stability of the algorithm has been improved greatly in this way. The experiments showed that this method was very promising.2769|638|0更新时间：2024-05-07
- 摘要：How to prevent quality degradation due to channel errors for images and video transmitting over lossy channels is a fundamental problem in multimedia signal processing. Support Vector Machine(SVM) is a novel powerful learning method and is now a new hotspot in the field of machine learning, and has been successfully used in many pattern recognition problems. To get more satisfying error concealment results, a novel error concealment scheme based on SVM is proposed in this paper. At first, a SVM based image interpolation algorithm is successfully established. SVM learning machines are carefully trained by a large amount of training data exacted from standard images to learn the relationship of neighboring pixels in spatial domain, and theses well trained machines are used as specific nonlinear interpolation operators. Comparative results show that this kind of interpolation operator outperforms not only some traditional used interpolation operators such as linear and median operators, but also some operators carefully trained by artificial neural networks. The error concealment problem is placed into a spatial image interpolation framework and the proposed interpolation method is thoroughly used to estimate the missing image blocks according to their neighboring pixels. Experimental results show that compared with some error concealment schemes both in spatial and frequent domain in the literature, especially those based on artificial neural networks, the proposed one has remarkable advantages in error concealment performance and generalization property.2179|491|0更新时间：2024-05-07
- 摘要：To compress the data during image digitalizeing, storage and transmission, We always use subsample method to sample the color channels in order to cut off data rate, Then use bilinearity method to reconstruct it. How to find the best way to reconstruct the color information lead us to study the principles of subsample problem. The Nayquest law limits the signal band width to half of sample rate. In subsample condition, this point will reduce sharpness of image and cause false color on image edges. This paper is focus on the problem of image reproduction under subsample condition. On study of the features of nature image and human eyes, We found there are similarities in details of image RGB color Channels. After analyse the subsample problem, We found it's possible to rebuild the subsample image if we have the information of image grade. Take consideration of this two points, we bring forth a new way to build the CCD color image, and found this way will improve the image sharpness remarkably.2428|428|0更新时间：2024-05-07
- 摘要：Scene model is one of key components of remote sensing physical models. Here, a computer scene model(CSM) was introduced. The CSM includes the parameterization of three dimensional landscape scene of a remote sensing pixel, data structure for the scene, methods and procedures for rendering the scene. In the CSM, generation of 3D architecturally realistic scene of a remote sensing pixel is based on vegetation measurement and statistics. Shape, size, base height and orientation of their leaves, and total height of corn and wheat firstly are measured by hand and by digital photogrammetry on field. Then the original data are normalized to obtain the feature parameter set of corn and wheat, which is used to rebuild single plant in computer. A remote sensing pixel usually consists of many plants, and positions of these plants in a pixel falls four interspersing patterns: random, regular, cluster, and transition. The CSM employs two methods to make 3D picture of a remote sensing pixel. The first rendering approach is based on the L system, which is applicable to plant with small number of big leaf, such as corn. The second one depends on statistics, which is applicable to plant with big number of small leaf, such as tree and grass. The 3D remote sensing pixel scene is used not only to show 3D pictures, but also to compute distribution function of energy by reflected or emitted by the remote sensing pixel. In order to do the calculation effectively and expediently, CMS records all polygons, which make up of the 3D scene, in a text file on an array of polygon. The polygon file is the ending of the CSM, and also the beginning of the pixel energy distribution calculation. The CMS produces successfully a 3D scene of a remote sensing pixel, which accords with statistics of the remote sensing pixel.2363|462|0更新时间：2024-05-07
- 摘要：The imaging spectrum technology is one of the foreland research field in the remote sensing development. Its main characteristics are hyperspectral resolution, high spatial resolution, high time resolution and composition of spectrum and image, It has been widely used in the civil economy. Based on analyzing imaging environment of the light aeroplane remote sensing system, this article deeply studied the geometric theory of low altitude remote sensing images. Adopting mathematics modeling method, the author established geometric distortion analysis methods and calibration models, and presents geometric processes. Using the models and software presented in this article, Geometric characteristics analysis and calibration has been carried out for the VIR/SWIR imaging spectrum data, and better processing results are achieved. Furthermore, these results also confirm the practicability of the model.2526|484|0更新时间：2024-05-07
- 摘要：Engineering analyses to assess image data quality are described and results are presented for the infrared multispectral scanner(IRMSS) of No.1 Chinese-Brazil Earth Resources Satellite (CBERS-1), which was launched on October 14, 1999. Data from CBERS-1 IRMSS and Thematic Map are compared. Based on the zero-level image acquired by CBARS-1 IRMSS on March 23, 2000, pre-processing was carried out, including radiation correction, noise cleanness, etc. Then a comprehensive assessment was conducted by five criterions such as signal/noise ratio (SNR), spatial resolution, contrast, radiometric precision and clarity. In comparison with TM. Bands 8 and 9 of CBERS-IRMSS had better clarity, Bands 6 and 7 had better contrast, Band 8 had better radiance precision. However, TM was found to produce image with much better SNR and spatial resolution. In addition, by image enhancement processing such as data fusion, the image quality can be improved greatly, and will be widely used in many fields such as resource survey and city plan.2891|523|0更新时间：2024-05-07
- 摘要：In this paper, an algorithm to rapidly generate adaptive LOD digital terrain model is presented. In the beginning, different methods to generate LOD digital terrain model are investigated. The design of the algorithm is Based on the quad-tree. The most important advantage of the algorithm is its ability to generate terrain model adaptively and quickly. The algorithm can generate various terrain model according to change of the original terrain model, the view direction, the view distance, and the capability of the display device. The algorithm can quickly changes between different LOD terrain models smoothly. The detail description of its design is presented in the paper, Moreover, the key functions of the algorithm are also provided in the paper. At the last part of the paper, two digital terrain model of Xiamen area on different LOD terrain models generated by the algorithm are illustrated, moreover, the time complex analysis for the algorithm is also presented. The theoretical analysis and practical testing show that the algorithm has good adaptive characteristic, and the algorithm can meet the needs of browsing and interacting with huge DTM nearly real-time.2314|447|0更新时间：2024-05-07
- 摘要：In the same zone, the remotely sensed datas of different sensor and different time have different space resolution,spectrum resolution and temporal resolution. Synthesizing their respective advantages, we can fetch up the scarcity of single image's information and extend its application field. In order to apply remote sensing image in terrain simulation, we must get the remote sensing image with high space resolution and high spectrum resolution. In this paper, we use the TM image, IKONOS image and same zone's DEM to make three demention terrain map. In order to keep the TM image's spectrum information and import the geometry character of IKONOS to fetch up the disadvantage of TM and IKONOS,we first use the polynomial method to geometry registration the IKONOS image and TM image,then we use the fusion algorithm base on HIS transformation fuse the TM image and IKONOS image. Experiment results show that we can get 1 meter image resolution's color image by fusing the 1 meter image resolution's panchromatic IKONOS image and 30 meter image resolution's color TM image. Finally,We apply the fusion result in the terrain simulation by merging the fusion's image with same zone's DEM to create high three demention terrain map.2553|427|0更新时间：2024-05-07
- 摘要：Point in-out polygon test is one of the fundamental issues in Computer graphics. In this paper, the fundamental characteristic of the polygon edges-monotonicity is utilized sufficiently. According to the coordinate relations between the points and the edges, the conception of correlative edges is proposed. By integrating monotonicity with correlative edges, a new algorithm of point in-out polygon is put forward. The new algorithm transforms the relationship between a point and a polygon into that between a point and its correlative edges. The operations of intersection are avoided, and the operations of cross product are reduced as far as possible. The efficiency of the algorithm is raised radically. It is proved simply and effectively when the points are at critical positions. Software implementation verifies the high robustness and efficiency of the new algorithm.2417|442|0更新时间：2024-05-07
- 摘要：Model simplification is very important in the fields of virtual reality and real-time simulation. In computer graphics, objects and scenes are often described by mesh models, such as terrain model, Stanford's scanning models and so on, but, a complicated model often includes large-scale data, the large data scale is a bottle-neck of fast-speed rendering, so it is necessary to simplify mesh model. The approach of levels of detail(LOD) is good, there have been some efficient algorithms for LOD and model simplification, these algorithms' simplification criteria are minimizing the geometry errors. It has been found that the last destination for simplification is to obtain fast rendering speed as well as good visual effects, hence, visual effects can and should become simplification criteria. This paper gives an algorithm of normal-based mesh model simplification. First, this paper gives a mathematics model for curve, and concludes that grads can express a curve's visual effects. Second, this paper uses normal of mesh models to replace grads, if the normal is averaged three times or more, a mesh can simulate a cure well, and the averaged normal can replace grads to become simplification criteria. Finally, this paper defines an angle between a normal of given point of intersection of the mesh model and those around this point, and uses this angle to simply mesh models. A group of experimental results are also given, which illustrate that the above algorithm can realize model simplification effectively, and at the same time, keep the models highly accurate.3031|589|0更新时间：2024-05-07
- 摘要：In this paper, a technique based on a discrete Kalman filter algorithm is proposed to follow the trajectory of the objects. The aim is to obtain a precise prediction of their position and motion. The accurate prediction improves both the recursive spatio-temporal segmentation and object tracking performances, enabling a high level understanding of the scene dynamics. The derived scene representation obtained finds applications in various domains. For instance, it is very well suited for dynamic scene analysis where a deep scene understanding is required. Typical examples are scene understanding and robot vision. It is also very appealing in the context-based video coding(MPEG-4). Experimental results have shown that this method is able to integrate over time the temporal information for each object and to interpolate or extrapolate its trajectory, correctly predict the position and the motion of temporal coherent objects. However, if the object has performed maneuvers, the Kalman filter fails in its prediction. In order to decide when is convenient to use the last estimated motion of the object instead of the Kalman prediction a test based on motion compensation error is used. Finally the proposed algorithm has shown its robustness in the presence of object occlusions.2606|477|0更新时间：2024-05-07
- 摘要：Web GIS is current GIS developing hotspot, the article beginning with analyzing the computing evolution process, points out that the Web distributed environment is the right way to make the traditional GIS industry reach the opening ideal, further step the paper summarizes the conception,characteristics, types and framework of Web GIS,try to bring forward the best plan to publish spatial data on network by analyzing and comparing the realizing methods(CGI,Plug-ins,Java),including network protocol extend ,new data model and its algorithm, complex data integration, and network optimizing method(distributed parallel computing), at last realizes it by a Web GIS browser (Java applet) programming case.4140|351|0更新时间：2024-05-07
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