Description And Reasoning On Uncertain Direction Relations Based On Dynamic Objects

Direction relation, which is one of the important spatial relations in spatial database, is used widely in many domains, including GIS, multimedia system and image database. But the direction relation is uncertain because of the fuzziness of geographical objects themselves, the imprecision of geographical information processing and the vagueness of mankind cognition about spatial direction relations, uncertainty is inherent property of direction relations. At present, the research on the uncertainty of direction relation is mainly based on static objects, while there is relatively little research on dynamic objects. Based on these, the description and reasoning on uncertain direction relations based on dynamic objects are studied and explored.First of all, the"cone"direction relation model based on static objects is extended, the uncertain direction relation model based on dynamic objects is proposed by analyzing the property of dynamic objects. At the same time, based on this model, the membership of direction relations based on dynamic objects is calculated, the calculation result can represent as the target objects that pertain to each direction, and this kind of calculation result matches people's cognitive habits precisely.Secondly, the property of uncertain direction relations reasoning is researched according to the model which is proposed in this paper. To the questions that the result of direction relations reasoning is not accuracy, the distance was brought into the fuzzy reasoning of direction relations, and then making the reasoning of uncertain direction relations with the quantitative and qualitative distance constraints respectively, the reasoning algorithms of uncertain direction relation are presented, and the theoretical proof for the correctness of this algorithms is performed.Finally, the experiment is designed according to the reasoning algorithms of uncertain direction relations with distance constraints which is proposed in this paper, the main member functions which are needed in experiment are implemented. And this paper introduced how to make the reasoning of uncertain direction relations with the quantitative and qualitative distance constraints by experiment.