2003 Vol. 28, No. 3
The idea of an integrated representation of outdoor and indoor in CyberCity GIS is put forward in this paper.Firstly,the difference between the representation of 3D buildings based on CAD and that based on GIS is introduced.The applications of 3D buildings based on GIS can not only implement some basic 3D GIS functions but also be combined with DEM,DOM and DLG data.Secondly,data management methods for outdoor and indoor scenes are discussed respectively.A pyramid structure for DEM/DOM data management and an R+ tree index for 3D vector data management in outdoor scenes are introduced.A subdivision method for floor plans in indoor scenes is discussed.Thirdly,dynamical visualization methods for outdoor and indoor scenes are discussed respectively.The LOD method and the memory paging technique are applied in outdoor scenes.The visibility method is applied in indoor scenes.Fourthly,the indoor is compared with the outdoor from some aspects such as dimensions,amount of data and visualization,fundamental data,objects,editing function,interactive querying function,and statistics function.Lastly,the idea of an integrated representation of outdoor and indoor in CyberCity GIS is summarized from vision,dynamical interactive walkthrough,data organization and management,GIS functions,and data loading.
Urban continuous operational reference system is one of the infrastructures of urban spatial data.It provides real time and post-processing precise positioning services to satisfy the demands of position,time and real time positioning in all kinds of fields.This paper emphases on the construction of urban CORS and introduces the structure and operation of CORS by taking Shenzhen's continuous operational reference system as the example.
This paper describes a method for the determination of orientation parameters of the uncalibrated images involved in the image-based reconstruction of architectural scenes.This approach is implemented in a collection of the geometrically intuitive vanishing point method and conditional least squares adjustment with unknown parameters algorithm.We exploit the abundant parallel and orthogonal object lines to find out the vanishing point for the main direction and sequentially lead to the initial orientation parameters values.Then,more precise and stable values are found by an optimizing algorithm,based on conditional least squares adjustment with unknown parameters.During the iterative process in this algorithm,orientation parameters of the image are recalculated.Last,these orientation parameters are used to reconstruct textures landscape of the buildings by combining the vector and texture data in image.
The original idea of assignment crossover was proposed by Yuchi Nagata and Shigenabu,who used this crossover in TSP problem solving and better result was obtained.This paper illustrates how assignment crossover can be used in image textural classification after modification.In assignment crossover,according to their prositions in the code,all genes in a chromsome is arranged into a circle,a pair of parent chromsomes thus form a pair of circle.With this method,one pair of parent individuals can produce two or three or even more crossover circuits,thus produce more than two new individuals in the new generation.To verify its validity,six objects,namely,bush land,residential areas,rivers,paddy field,drought areas and mountain areas,are grouped into three main types:Ⅰ-bush land,rivers,paddy field;Ⅱ-bush land,residential areas,drought areas;Ⅲ-bush land,residential areas,mountain areas.For each group,a "tuned" mask is generated for purpose of textural classification experiment.
This paper introduces the actuality of managing pipeline,proposes the data structure of 3D pipeline object,which can meet the requirements of 3D spatial representation and interactive operation.Then the paper illustrates how to build the 3D model of underground pipeline and the method of model calculating.The interactive operation about 3D object and the solution to problems which are met during the interactive operation are introduced.An experimental system prototype is developed based on C++ and OpenGL,and several experimental results are illustrated.
In traditional planar maps,we use symbols to represent spatial objects.With the development of computer technique and 3D techniques and their application in GIS,traditional 2D static planar map is developed to 3D dynamic virtual environment.CyberCity is a hotspot in the field of GIS and it needs not only by DEM and 3D terrain to deliver the topographic information,but also 3D symbol models to represent spatial objects.Representation of CyberCity is not reconstruction in all details,but based on the abstraction and interpretation of real world according to the temporal-spatial,economic and technical constraints.So it is necessary to study on the 3D model.This paper discusses the transmission pattern of spatial information,the difference and relations between map symbols and 3D models,then illustrates the principles of 3D models based on their determinability,location,simplification and logicality.
With the development of aerial and spatial remote sensing technology of China,the ground receiving station stores and manages mass spatial data at TB level.Thus,the traditional distribution mode cannot meet the application demand.So as to meet the demand of network informazation,it is required that the mass spatial data be distributed,shared and processed on the special network.Functions as online browsing,distribution and processing of spatial data,especially the mass spatial data have become an important research orientation in geographic information service.The paper focuses on the principles and key technologies of mass spatial data online distribution system based on J2EE.An instance of mass image spatial data online browsing and distribution is given.
At present,the construction of National Spatial Data Infrastructure(NSDI) and Digital Earth imminently needs efficient management of multi-scale and multi-resource mass image data.This paper gives systematic and deep researches on distributed heterogeneous management mode of super-image-project and image-project based on commercial database management system(such as ORACLE,SQL Server) and Component Object Modal(COM) after the characteristics of image data and its management requirement is comprehensively analyzed.The design and implementation method for large-scale seamless image database management system is also described.
The paper puts forward spatial information natural language query interface(SINLQI),which can make a geographical information system easier to use.The authors discuss the establishment of dictionary based E-R semantic,Chinese word segmentation,query grammar rule,application field etc.The authors design a set of common interfaces for dictiorary organizing,word processing,grammar and semantic analysis.Using these interface,The authors implement a SINLQI demo based wireless application protocol(WAP).It establishes a base for applying SINLQI to GIS project.
Spatial indexing techniques can efficiently improve the storage and query efficiency.IN the large spatial database of GIS,the traditional spatial indexing structures,the R-tree has the problem that with the growing dimensionality and data number,the searching function will decrease greatly.On the basis of the analysis of R-tree,this paper puts forward a new spatial indexing structure for GIS with very large spatial database-the QR-tree.
This paper analyzes the reasons causing hue(or gray) difference of large-scale image database.Then on the basis of the comparison of some general methods,the paper presents a new hue(or gray) adjustment and smoothness transition method.Meanwhile,in order to reduce spatial transfer error caused by adjusting large-scale images,an innovative multi-time adjustment algorithm based on quad tree is put forward.
The analysis of the remotely sensed images evolves in three stages:physical classification,semantic extraction,and information recognition.This paper proposes a new method for integrating the three stages into one common platform.Through this method,semantic extraction and information recognition can be synthetically performed with the classification procedure in the image processing.The mechanism analyzing the relationship in a multi-resolution hierarchy benefits the better understanding to the image objects,in both semantic and physical ways.Consequently,this method can be used for integration of remote sensing and GIS at semantic level.
A new method is presented for constitution of series LOD model of TIN terrain and dynamic display.The method is divided into two steps.One is to setup the series LOD model of TIN terrain by deleting vertices.On the basis of modification of data-structure,we record all information of points and triangles along the simplification of TIN.The other is to dynamic display based on the distance between viewpoint and viewer.
InSAR is an effective measurement for generating large scale and accurate digital elevation modeling(DEM).It is a necessary step in the InSAR processing that removing flat earth effect.It makes the phase of interferogram exhibit the contour line of terrain and makes the unwrapping processing easily.DEM can be calculated from interferometric phase without unwrapping processing when the maximum difference of elevation is less than the ambiguous height decided by baseline.A removing flat earth method based on geolocation is introduced in this paper.And its validity is illuminated by test results.
For digital maps and GIS data,locating the inflection point can be performed in two steps.One is to sweep the original polyline to find a side where there exist inflection points.To perform this task,we use the every four consecutive points forming two cross products of two vectors.If the multiplication of these two cross products gives a value with positive sign,it means that these four consecutive points have the same concavity,otherwise,the four points form two curve segments,with signs opposed each other.The other step is to locate the inflection point on the side found before.For this purpose,an auxiliary smooth interpolation is needed as a bridge.Our task is to find a simplified method to locate the inflection point without bridging interpolated and smoothed curve.Through regression analysis it is observed that the inflection point is located on the side of original polyline approximately and moves along this side in dependence on the angle ratio at rotation angles at the incident vertices.Therefore,we can calculate the rotation angles at vertices of relevant original side found in the first step.Using the exponent value obtained from the regression analysis and calculating the angle ratio at two vertices in advance,a desired inflection point can be calculated directly by the original data without interpolation procedure.In the end,this paper presents several main application aspects of inflection point.
The determination theory of coordinate system for real batch-bulk industrial components and surveying method are presented in detail.The general principles for selecting coordinates system of industrial component are proposed.The suggestions to select the instruments are given and the structures of some tools for inspecting and setting out are also presented.The theory and methods given are suitable under on-line conditions with computer and have been used for components of Yangtse River Bridge in Wuhu.The accuracy for lofting screw holes is ±0.35mm.
For the determination of high precise(centimeter level) local gravimetric geoid,it is very important to determine the terrain effects on geoid undulations.The effect of grid spacing of digital topographic model on terrain corrections and geoid undulations and the indirect terrain effect on geoid undulations are studied,as well as the effect of mass prism and mass line topographic models on terrain corrections.And the differences of the total terrain effect on geoid undulations by classical Stokes-Helmert method and Sjöberg's method are discussed and compared.Finally,some practical conclusions and suggestions are drawn from the test results of Hong Kong geoid determination.
On the basis of BEM(boundary element method),DDA(discontinuous deformation analysis) and Least Square Principle,a method for determining relative movements on boundaries,displacements and stresses in blocks of a multi-block system is presented,the stress and kinematic constraints required for the movement reasonability of the block system are discussed,and the judgment of the contact status between blocks is also investigated in detail,that ensures whether stress and kinematic constraints are necessary.In one word,an inversion method of DDA with BEM is provided,that would be a more effective numeric computing method for larger-scale crustal deformation analysis.
This paper presents a new method for the detection of moving targets from image sequence.some modification are made to the traditional method based on optical flow field.This method of object detection is simple and efficient。Experiment results are given to demonstrate the effectiveness and practicality of the method.
It has been attracting wide attention to retrieval,analysis and understanding of huge video data.A number of content based methods for indexing and retrieving have been presented.Text detection and extraction in video images is an effective way for achieving image-content-based retrieval.This paper presents a method for detecting and locating text areas in images based on sub-image VCH.The mapping features of sub-image VCH and the relation between texts and mapping features is analyzed.And the algorithm for detecting and locating text areas in images is described.Some computing experiment results are given and analysis and evaluation are made for it in the end of the paper.
This paper discussed the model and implementation of a tobacco grading system based on image features.We proposed the mathematical description of the grading model,and discussed the optimization of the model base and the calculation of the membership of the features and the confidence of the tobacco pattern.The experimental results shows the performance and efficiency of the FTGS.
The optimal design of water distribution network is an optimization problem of functions that depend on a series of nonlinear discrete multi-variables.Many traditional methods are not satisfactory when applied in this field.This paper introduce a relatively novel algorithm,genetic algorithm(GA),which has special advantages in tackling this problem based on its inherent characteristics.This paper gives an overall introduction of basic principles of GA and analyzes the characteristics of water distribution system optimization design.A mathematical model is put forward.Some problems on the software solutions of several key GA operators and the hydraulic computation constraint factors are discussed.Lastly this paper chooses a case study to demonstrate the feasibility of GA in this field.It makes a comparison between two water supply schemes for a residence region.
Taking use of digitizing technique,this paper discusses how to develop a canal automatic control system,combining with theories of Hydraulics,Fuzzy control,set up the mathematics mould of canal automatic moving system,design a fuzzy control system,present its fuzzy rules and membership functions etc,so that the system is more stable and more rational.At last,the system actual parameters are simulated in MATLAB,providing important data and basis for making decision and canal system moving automatically.