摘要:

The techniques of fuzzy logic and Monte Carlo simulation are combined to address two incompatible types of uncertainty present in most natural resource data: thematic classification uncertainty and variance in unclassified continuously distributed data. The resultant model of uncertainty is applied to an infinite slope stability model using data from Louise Island, British Columbia. Results are summarized so as to answer forestry decision support queries. The proposed model of uncertainty in resource data analysis is found to have utility in combining different types of uncertainty, and efficiently utilizing available metadata. Integration of uncertainty data models with visualization tools is considered a necessary prerequisite to effective implementation in decision support systems.

ISSN:1365-8816    

DOI:10.1080/136588197242239

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Property value is a function of locational, physical, legal and economic factors. The prevalent method of valuation is the comparison technique which involves the analysis of properties similar to the one being valued in order to isolate and quantify individual influences on value. A primary factor that affects real estate value is location (Goodall 1972) yet the quantification of this factor in the valuation process is traditionally accounted for by the valuer's expert knowledge of a locality. This paper demonstrates that a more quantitative approach to the analysis of spatial property information would enhance the real estate valuer's understanding of locational influences on property value. To achieve this a GIS-based property valuation database was developed for a study area that permitted the geographical representation of property information at the individual property level. Network analysis was then used to examine the influence of accessibility on property value and value maps were constructed to illustrate the resultant geographical spread of property values. It is suggested that this aids the valuer in the selection of comparable evidence based on locational criteria.

ISSN:1365-8816    

DOI:10.1080/136588197242248

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Simple but objective criteria for evaluating the quality of DTMs, derived from digital contour lines, are defined. Such criteria are then applied to terrain models, obtained by means of four different procedures, which refer to three sample areas characterized by complex morphological settings. The results of the comparison shows that each DTM is affected by one or more types of error or pitfall; however, one TIN generator and one grid interpolator proved to be capable of effectively producing terrain models which largely reflect the ground morphology as expressed by the input contour lines.

ISSN:1365-8816    

DOI:10.1080/136588197242257

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Clear sky shortwave solar radiation varies in response to altitude and elevation, surface gradient (slope) and orientation (aspect), as well as position relative to neighbouring surfaces. While the measurement of radiation flux on a relatively flat surface is straightforward, it requires a dense network of stations for mountainous terrain. The model presented here uses a digital elevation model to compute potential direct solar radiation and diffuse radiation over a large area, though the model may be modified to include parameters such as cloud cover and precipitable water content of the atmosphere. The purpose of this algorithm is for applied work in forestry, ecology, biology and agriculture where spatial variation of solar radiation is more important than calibrated values. The ability of the model to integrate radiation over long time periods in a computationally inexpensive manner enables it to be used for modelling radiation per se, or input into other hydrological, climatological or biological models. The model has been implemented for commercially available GIS (viz. Arc Info and Genasys) and is available over the Internet.

ISSN:1365-8816    

DOI:10.1080/136588197242266

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The modelling of environmental processes based on catchment elevation surfaces is well-established, but the use of TIN and grid surface models as three-dimensional representations of river channel topography at the reach scale is much less common. In this paper, surface modelling facilities in ARC/INFO GIS have been used to model the geometry of seven short sections of gravel-bed river channels in upland Britain from field surveys taken in 1976 and 1994. The methods used in converting field survey data and implementing bed-topography models as TIN and grid data structures are described. The use of derived surface models to define pool-riffle bedforms, estimate sediment budgets and assess channel change between surfaces of different dates are discussed and evaluated.

ISSN:1365-8816    

DOI:10.1080/136588197242275

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1365-8816    

DOI:10.1080/136588197242284

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor