重叠矩形图像表示及其上的精确Legendre矩计算(英文)

Linear quadtree is a popular image representation method due to its convenient imaging procedure. However, the excessive emphasis on the symmetry of segmentation, i.e. dividing repeatedly a square into four equal sub-squares, makes linear quadtree not an optimal representation. In this paper, a no-loss image representation, referred to as Overlapped Rectangle Image Representation （ORIR）, is presented to support fast image operations such as Legendre moments computation. The ORIR doesn＇t importune the symmetry of segmentation, and it is capable of representing, by using an identical rectangle, the information of the pixels which are not even adjacent to each other in the sense of 4-neighbor and 8-neighbor. Hence, compared with the linear quadtree, the ORIR significantly reduces the number of rectangles required to represent an image. Based on the ORIR, an algorithm for exact Legendre moments computation is presented. The theoretical analysis and the experimental results show that the ORIR-based algorithm for exact Legendre moments computation is faster than the conventional exact algorithms.     

COMPUTER-AIDED DESIGN OF MAP COLOR

The design of map color is an important part in map design, especially for thematic mapping, importance is no less than that of map content itself.Tranditional method in map color design is to make several designing variants and then make a comparison among them and finally choose one of them.This method is time-consuming and rather expensive.With the development of interactive computer graphics,now the design of map color can be completed by means of computer processing. During this procedure, cartographer's knowledge in map design, rich color in computer and the powerful functions of graphic processing of computer can be combined together. Three main problems about comprter-aided design of map color are discussed in this paper: The first is to create a database which forms the basis of color producing; the second is to create a cartographic database for organized raster data; the third is to design an interactive svstem for the design of map color with the support of the two databases mentioned above.     

The generic annular bucket histogram for estimating the selectivity of spatial selection and spatial join

Selectivity estimation is crucial for query optimizers choosing an optimal spatial execution plan in a spatial database management system.This paper presents an Annular Bucket spatial histogram(AB histogram)that can estimate the selectivity in finer spatial selection and spatial join operations even when the spatial query has more operators or more joins.The AB histogram is represented as a set of bucket-range,bucket-count value pairs.The bucket-range often covers an annular region like a sin-gle-cell-sized photo frame.The bucket-count is the number of objects whose Minimum Bounding Rectangles(MBRs)fall between outer rectangle and inner rectangle of the bucket-range.Assuming that all MBRs in each a bucket distribute evenly,for every buck-et,we can obtain serial probabilities that satisfy a certain spatial selection or join conditions from the operations’ semantics and the spatial relations between every bucket-range and query ranges.Thus,according to some probability theories,spatial selection or join selectivity can be estimated by the every bucket-count and its probabilities.This paper also shows a way to generate an updated AB histogram from an original AB histogram and those probabilities.Our tests show that the AB histogram not only supports the selectivity estimation of spatial selection or spatial join with "disjoint","intersect","within","contains",and "overlap" operators but also provides an approach to generate a reliable updated histogram whose spatial distribution is close to the distribution of ac-tual query result.     

Geospatial Information Service Based on Digital Measurable Image——Take Image City·Wuhan as an Example

LBS (location-based service) is a remarkable outcome of the development from GIS to geospatial information service. Faced by the requirements of geospatial information from the masses and the opportunity provided by the next generation Internet and Web 2.0, a new model of geospatial information service based on DMI (digital measurable image) is presented. First, the concept of LBS and the opportunities of Web 2.0 are introduced, then the characteristic of DMI is discussed. Taking the Image City·Wuhan as an ...     

数字地形建模的真三维TIN算法研究

The problem of taking an unorganized point cloud in 3D space and fitting a polyhedral surface to those points is both important and difficult. Aiming at increasing applications of full three dimensional digital terrain surface modeling, a new algorithm for the automatic generation of three dimensional triangulated irregular network from a point cloud is proposed. Based on the local topological consistency test, a combined algorithm of constrained 3D Delaunay triangulation and region-growing is extended to ensure topologically correct reconstruction. This paper also introduced an efficient neighboring triangle location method by making full use of the surface normal information. Experimental results prove that this algorithm can efficiently obtain the most reasonable reconstructed mesh surface with arbitrary topology, wherein the automatically reconstructed surface has only small topological difference from the true surface. This algorithm has potential applications to virtual environments, computer vision, and so on.     

DEM Compression Based on Integer Wavelet Transform

DEM data is an important component of spatial database in GIS. The data volume is so huge that compression is necessary. Wavelet transform has many advantages and has become a trend in data compression. Considering the simplicity and high efficiency of the compression system, integer wavelet transform is applied to DEM and a simple coding algorithm with high efficiency is introduced. Experiments on a variety of DEM are carried out and some useful rules are presented at the end of this paper.     

An efficient solution for building polygonal objects

Polygonal object is a fundamental type of geometric data in vector GIS. The key step of cleaning topological relationship after data collection of polygonal layer is to build polygonal objects from digital arcs. The raw digital arcs may intersect with each other. The algorithm for building polygonal objects after the raw arcs have been split at all intersections is presented. The build-up of polygonal objects in this paper is designed to be implemented by two steps. The first step is to extract all the polygons needed for build-up of polygonal objects from arcs. The second step is to organize polygonal objects from these polygons. For the first step, a tracing algorithm is proposed. The algorithm merely extracts the polygons needed for the build-up of polygonal objects, which is a subset of all the possible polygons that can be induced from the arcs. For the second step, an algorithm based on a specially designed order of polygons is advanced. All the topological relationships among the polygons are sho     

Application of interval Newton method to solve nonlinear equations and global optimization

The basic principle of interval arithmetic and the basic algorithm of the interval Newton methods are introduced.The prototype algorithm can not find any zero in an interval that has zero sometimes,that is ,it is instable.So the prototype relaxation procedure is improved in this paper.Additionally,an immediate test of the existence of a solution following branch-and-bound is proposed,which avoids unwanted computations in those intervals that have no solution.The numerical results demonstrat that the improved interval Newton method is superior to prototype algorithm in terms of solution quality,stability and convergent speed.     

Positional error curves band of a planar line segment within GISs

1 Introductionffe well-for Meanboha Eno(MSRE),having advanop of talculang ndy,has bo widdyed to m the W of pont ednates inGIS' NY and gedop. N, it is Me tDtw the opiW eno Of a pont in whitw dirm-tion, while in praedce there is ned tO for the value ofghH or Of a trint in a peial boon SUCh asthe uha diW. The or curve of a glnt is ableto W twl the diAnbution wttiOn of twnt eno.ln an arbtw dich and it is the nd efhaive edfor dedbing forhed rm Of odnts in SUrVopng..mpneenng(Mithel, 1983…     

An integrated and layered architecture for location-aware computing

This paper gives an overall introduction to the basic concept of LAC(location-aware computing) and its development status, puts forward an integrated location-aware computing architecture which is useful for designing the reasonable logical model of LBS(location-based service). Finally, a brief introduction is conducted on a LAC experimental prototype, which acts as a mobile urban tourism assistant.     

An improved direction relation detection model for spatial objects

Direction is a common spatial concept that is used in our daily life. It is frequently used as a selection condition in spatial queries. As a result, it is important for spatial databases to provide a mechanism for modeling and processing direction queries and reasoning. Depending on the direction relation matrix, an inverted direction relation matrix and the concept of direction pre- dominance are proposed to improve the detection of direction relation between objects. Direction predicates of spatial systems are also extended. These techniques can improve the veracity of direction queries and reasoning. Experiments show excellent efficiency and performance in view of direction queries.     

Comparative study on two methods for calculating the gravitational potential of a prism

The determination of the gravitational potential of a prism plays an important role in physical geodesy and geophysics. However, there are few literatures that provide accurate approaches for determining the gravitational potential of a prism. Discrete element method can be used to determine the gravitational potential of a prism, and can approximate the true gravitational potential values with sufficient accuracy (the smaller each element is, the more accurate the result is). Although Nagy’s approach provi...     

大型土木工程结构的动态位移远距离实时监测系统(英文)

Based on digital image processing technique, a real-time system is developed to monitor and detect the dynamic displacement of engineering structures. By processing pictures with a self-programmed software, the real-time coordinate of an object in a certain coordinate system can be obtained, and further dynamic displacement data and curve of the object can also be achieved. That is, automatic gathering and real-time processing of data can be carried out by this system simultaneously. For this system, first, an untouched monitoring technique is adopted, which can monitor or detect objects several to hundreds of meters apart; second, it has flexible installation condition and good monitoring precision of sub-millimeter degree; third, it is fit for dynamic, quasi-dynamic and static monitoring of large engineering structures. Through several tests and applications in large bridges, good reliability and dominance of the system is proved.     

Automatic placement of GIS vector map annotation in area feature by long-diagonal

IntroductionMap is a graphics expression of spatial infor-mation. Map language includes map symbolwhose basic languageis graphics ,and map anno-tation as nature language (letters) . Map annota-tion plays an i mportant role in computer aidedcartography and GIS.It is a complementarityformap graphics and makes the map hold richer in-formation[1].Map annotation is one of the international ar-duous problemsin automatic map generalization.With the development of computer technology ,the automatic …     

Principal component analysis in application to object orientation

This paper proposes a new method based on principal component analysis to find the direction of an object in any pose.Experiments show that this method is fast,can be applied to objects with any pixel distribution and keep the original properties of objects invariant.It is a new application of PCA in image analysis.     

House change detection based on DSM of aerial image in urban area

The change of house often brings on the change of DSM in an area over different periods. If we can apply information of the height of houses to reinforce the house change detection, the reliability and efficiency of detection methods will be improved greatly.From this viewpoint, a new approach taking advantage of both height data from an image pair and image data is proposed to detect the house change in urban area and is called "data fusion technology".