41,422 research outputs found
Multi-dimensional modelling for the national mapping agency: a discussion of initial ideas, considerations, and challenges
The Ordnance Survey, the National Mapping Agency (NMA) for Great Britain, has recently
begun to research the possible extension of its 2-dimensional geographic information into a
multi-dimensional environment. Such a move creates a number of data creation and storage
issues which the NMA must consider. Many of these issues are highly relevant to all NMA’s
and their customers alike, and are presented and explored here.
This paper offers a discussion of initial considerations which NMA’s face in the creation of
multi-dimensional datasets. Such issues include assessing which objects should be mapped in
3 dimensions by a National Mapping Agency, what should be sensibly represented
dynamically, and whether resolution of multi-dimensional models should change over space.
This paper also offers some preliminary suggestions for the optimal creation method for any
future enhanced national height model for the Ordnance Survey. This discussion includes
examples of problem areas and issues in both the extraction of 3-D data and in the
topological reconstruction of such. 3-D feature extraction is not a new problem. However, the
degree of automation which may be achieved and the suitability of current techniques for
NMA’s remains a largely unchartered research area, which this research aims to tackle.
The issues presented in this paper require immediate research, and if solved adequately
would mark a cartographic paradigm shift in the communication of geographic information –
and could signify the beginning of the way in which NMA’s both present and interact with
their customers in the future
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Computer assisted mathematical programming
A Computer Assisted Mathematical Programming (Modelling) System (CAMPS) is described in this paper. The system uses program generator techniques for model creation and contrasts with earlier approaches which use a special purpose language to construct models. Thus no programming skill is required to formulate a model. In designing the system we have first analysed the salient components of the mathematical programming activity. A mathematical programming model is usually constructed by progressive definition of dimensions, data tables, model variables, model constraints and the matrix coefficients which connect the last two entities. Computer assistance is provided to structure the data and the resulting model in the above sequence. In addition to this novel feature and the automatic documentation facility, the system is in line with recent developments, and incorporates a friendly and flexible user interface
Spatial interactions in agent-based modeling
Agent Based Modeling (ABM) has become a widespread approach to model complex
interactions. In this chapter after briefly summarizing some features of ABM
the different approaches in modeling spatial interactions are discussed.
It is stressed that agents can interact either indirectly through a shared
environment and/or directly with each other. In such an approach, higher-order
variables such as commodity prices, population dynamics or even institutions,
are not exogenously specified but instead are seen as the results of
interactions. It is highlighted in the chapter that the understanding of
patterns emerging from such spatial interaction between agents is a key problem
as much as their description through analytical or simulation means.
The chapter reviews different approaches for modeling agents' behavior,
taking into account either explicit spatial (lattice based) structures or
networks. Some emphasis is placed on recent ABM as applied to the description
of the dynamics of the geographical distribution of economic activities, - out
of equilibrium. The Eurace@Unibi Model, an agent-based macroeconomic model with
spatial structure, is used to illustrate the potential of such an approach for
spatial policy analysis.Comment: 26 pages, 5 figures, 105 references; a chapter prepared for the book
"Complexity and Geographical Economics - Topics and Tools", P. Commendatore,
S.S. Kayam and I. Kubin, Eds. (Springer, in press, 2014
How about building a transport model of the world?
The paper provides a specification, created by the recently completed BLUEPRINT project, for a world transport network model. The model should be able to make predictions (up to 100 years into the future) of transport flows throughout the world and hence make predictions of global climate-changing emissions arising from transport. Furthermore, the model should: cover both passenger and freight traffic; feature all modes of transport (road, rail, non-motorised, water, air and pipeline); and represent both local traffic and long-distance traffic. The paper describes how the model will be structured as the combination of a global model (distinguishing between approximately 30 different geographic regions of the world) and a number of regional and sub-regional models. Wherever feasible, existing regional models will be used in this system, or at least simplified versions of such models. The overall modelling system should be owned jointly by an international network of world transport modellers, welcoming easy entry to other modellers who subscribe to the underlying spirit of the network. The paper recognises the scientific complexities associated with the uncertainties of predicting 100 years into the future and with difficulties arising from the likely differences in modelling philosophy between the (already existing) regional models that might be used in the modelling system. In order to tackle these complexities, the paper defines a number of philosophy of science reference points. At the core of these reference points is the distinction between objectivity and subjectivity. The paper finishes with a number of suggestions for next steps in building the model
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