ISSN:1365-8816    

DOI:10.1080/136588198241978

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Ordering a set of multi-dimensional data is an essential task in modern spatial data processing systems such as raster geographical information systems. This can effectively be carried out by a transformation called spatial ordering. It has been reported that the H ilbert order exhibits desirable performance. However, its encoding or decoding process in the n -dimensional space (n 3) is complicated and would place a considerable computational burden on the application problems. In this paper, we propose a new spatial order with efficient algorithms. The performance evaluation suggests that this new order is competitive with the Hilbert order.

ISSN:1365-8816    

DOI:10.1080/136588198241987

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper we show how a Bayesian network of inference can be used with a GIS to combine information from different sources of data for classification. Data may include satellite sensor images, topographic maps, geological maps etc, each one with its own resolution and accuracy. We show how this uncertainty in the input data can be incorporated in the network and present various methods by which the conditional probability matrices used by the network can be constructed. We demonstrate our approach within the framework of the problem of assessing the risk of desertification of some burned forests in the Mediterranean region.

ISSN:1365-8816    

DOI:10.1080/136588198241996

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We study the accuracy of data on some local topographic attributes derived from digital elevation models (DEMs). First, we carry out a test for the precision of four methods for calculation of partial derivatives of elevations. We find that the Evans method is the most precision algorithm of this kind. Second, we produce formulae for root mean square errors of four local topographic variables (gradient, aspect, horizontal and vertical landsurface curvatures), provided that these variables are evaluated with the Evans method. Third, we demonstrate that mapping is the most convenient and pictorial way for the practical implementation of the formulae derived. A DEM of a part of the Kursk Region (Russia) is used as an example. We find that high errors of data on local topographic variables are typical for flat areas. Results of the study can be used to improve landscape investigations with digital terrain models.

ISSN:1365-8816    

DOI:10.1080/136588198242003

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper presents a prototype of a simulation model based on cellular automata (CA), and multicriteria evaluation (MCE) and integrated with GIS. Specifically, a method, analytical hierarchy process (AHP), of MCE is used here to derive behaviour-oriented rules of transition in CA. A ‘tight' integration strategy is adopted, which means that the modules of MCE and CA are written in the C programming language and built within ARC/INFO GIS. Designed to run on a workstation Unix SimL and fully utilizes the graphical user interface (GUI),which allows the modelto be driven by menusand automate the simulation of land conversion in the urban-rural fringe. The combination of three elements, GIS, CA, and MCE, has several advantages: visualization of decision-making, easier access to spatial information, and the more realistic definition of transition rules in CA.

ISSN:1365-8816    

DOI:10.1080/136588198242012

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A method is proposed for the generation, from multi-variate data, of classes with a spatially coherent distribution. The procedure is more appropriate for large data sets than is spatially constrained clustering based on modification of a similarity matrix. It is based on fuzzy clustering of the data, followed by spatially weighted averaging of the class memberships within a local neighbourhood. A coherence index is proposed which may be used to select an appropriate neighbourhood for this smoothing procedure. The effects of smoothing on the uniformity of the classes with respect to the variables used to define them may be measured by Wilks's criterion,and examination of the class means. The method is demonstrated on a multi-variate data set.

ISSN:1365-8816    

DOI:10.1080/136588198242021

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:1365-8816    

DOI:10.1080/136588198242030

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:1365-8816    

DOI:10.1080/136588198242049

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor