Haicheng Xu

A dynamic Access Control model based on trust

Since Role-Based Access Control (RBAC) shows great advantage in meeting the security need in large-scale and enterprise-wide system, RBAC becomes the hot topic in access control research field. However, current approaches to access control are mostly based on individual user identity; hence they do not scale to distributed systems. So, the paper analyses RBAC could not satisfy dynamic access control in distributed environment, and puts forward an dynamic access control model based on roles and trust control, giving every trust value for each user by introducing trust management to access control, each role corresponds a certain trust vale, users and systems give values for each other after operation, trust management modesties and updates trust values, users roles will change accordingly, The experiment shows that the model is much validated, and something useful is obtained. The extended model can meet the need to manage and enforce the strong and efficient access control technology in large-scale environments. The flexility and broad application of the proposed model through the system is testified and something useful is obtained.

Rapid Acquirement and Visualization of CityGML Documents

With the development of the Internet, the need of city 3D data is rising more and more, and the emphasis shifts from analysis to the sharing of city 3D data and information over the Internet. In Internet, we lack uniform 3D data standard and 3D data cannot be shared and exchanged availably. The city Geography Mark-Up Language (GML) was developed as the standard language for exchanging and sharing city 3D data in Internet. In this paper, we propose a set of data structures to obtain city 3D information from the GML file in order to extract useful information quickly, after analyzing CityGML files structure and parsing by the Document Object Model (DOM). The experiment shows that 3D data are extracted effectively, and visualized in Web application using Java, and the data structures defined in the paper are very validated.

A Kind of Map Coloring Algorithm Considering of Depth First Search

Map coloring problem is a hot topic in combinatorial optimization, which is one of the main tasks in discrete mathematics. It has gone through a long time for map coloring, especially with the development of computer wide applications. Map coloring theories has a long development, its applications are widely used. So, we propose a kind of map coloring algorithm based on depth-first search algorithm. the algorithm overcomes the shortcomings of the map colored areas compared to other algorithms. The experiment showed that the map coloring algorithm put forward by the paper is much valid, which could link these two types of data, and something useful is obtained.

Optimization Model for GPS Height Fitting Considering of AIC

Polynomial fitting method is widely used in GPS height conversion into normal heights in survey engineering and whcih has become a hotspot. Different models used in different area of interpolation have different precisions, therefore, it is very important to optimize model before GPS height conversion in order to obtain high precision. Lots of engineering practice has proven that The conicoid model could satisfied forth degree demand, but there is no proof why the conicoid model is better. So, the paper introduce AIC to choose the better model for transforming GPS height, we separate the value of AIC into two parts, AICin and AICout, then add them up to obtain the total value, AICtotal, which could testify which model is the best model comparing with the relative information. The experiments show that the optimization model for GPS height fitting considering of AIC criterion is valid and something useful is concluded.

Notice of Retraction A Hybrid Conversion of GPS Height Approach Based on Neural Networks and EGM96 Gravity Model

How to transfer GPS heights into normal heights has become a hotspot in survey engineering. With the development of computer and information technology, artificial neural networks (ANN) has been used widely, which has the character of the high parallel distributed processing, associative memory abilities, self-organization, self-learning and strong nonlinear mapping abilities, and the theory has proved that one ANN, having deviation and one S-type hidden layer or more plus one linear output layer, could approach any rational function, and the ANN has been used in GPS heights conversion. EGM96 is a gravity model of the earth, which has high precision of long wavelength contribution, so the paper puts forward a hybrid approach for conversion of GPS height Based on neural networks and EGM96. Remove the long wavelength from GPS/leveling points, next construct a model from the leaving parts fitted by BP neural network to calculate other GPS points, and restore the long wavelength to the points. The experiments show that the hybrid approach is much validated and something useful is obtained.

An Approach for 3D Reconstruction from Uncalibrated Images

Three-dimensional (3D) reconstruction considering of image sequences is an unresolved and active research topic on the cross-section of computer vision and digital photogrammetry. In this paper, we focus on 3D object shape reconstruction from uncalibrated images and put forward a rapid algorithm to recover the object height. The recovering 3D shape comprises two steps, for the one hand, calculate homography transformation to obtain the outlines, for the other hand calculate the reconstructed object height by reference height proposed by the paper, and then recover the 3D object shape. This method requires no camera calibration or the estimation of the fundamental matrix; hence, it reduces the computational complexity by eliminating the requirement for abundant conjugate points. The experiment shows that the method is much validated and something useful is obtained.

A Test of Artificial Neural Network-Based Gross Error Detection Used in Conversion of GPS Heights

Artificial neural networks (ANN) has been used in GPS heights conversion. It is impossible to avoid gross errors in conversion of GPS heights. So, the paper puts forward a kind algorithm to detect gross error considering of ANN used in conversion of GPS heights. After the three tests, the algorithm proposed for disposing of gross error is validated in conversion of GPS heights, and some practicable conclusions are received.

The Research of 3D Reconstruction from Uncalibrated Image Sequences Combined with 3D Models

3D reconstruction from uncalibrated image sequences is very important technology in computer vision. However, we only get 3D point cloud reconstructed from the image sequence, so the paper puts forward a kind of 3D reconstruction method considering of image sequences combined with 3D models taking advantages of parallel lines and vertical lines in features extracting. The experiment shows that the combined method is much validated.

Binocular Stereo Vision Measuring System Based on Structured Light Extraction Algorithm

With the rapid development of computer technology and photogrammetry, the binocular 3D measurement has been widely used in many fields such as quality inspection and reverse engineering. Depending on the application, there are different requirements for 3D measurement systems. Structured light image feature extraction is an important part of the binocular measurement system to achieve three-dimensional reconstruction. So, the paper puts forward a kind of approach for edge detection and edge tracking, using the edge tracking algorithm proposed by the paper to extract structured light stripes, and the method using chain code track record of the extracted features, and something useful is obtained.

Conversion and Information System Management of GPS Heights Based on MapObjects

Conversion of GPS heights into normal heights has become a hotspot in survey engineering, the Quasi-geoid surface can be very complicated especially in a large survey area or in complicated terrain, just adopting several GPS/leveling points to construct quadric surface model to fit the Quasi-geoid surface has some limitations, precision could not be guaranteed. So, such demand us that we should partition large survey area into several small one as possible especial in complicated area, and then fit the Quasi-geoid surface. Dense and distribution of GPS/leveling points determines the precision of the interpolation points. We should construct each sub-area mathematical model to interpolate other points, choosing GPS/leveling points by the position of interpolation points in order to obtain higher precision. For calculators, choosing GPS/leveling points for each interpolation point and constructing errors formula is complicated and has much work and time. So the paper design an information system for conversion GPS height and GPS points management based on MapObjects instead of fussy operation, the merit of the designed system could be described in terms of efficiency, flexibility and practicability, and something useful is obtained.