基于地图载负量的海洋流场欧拉法多尺度表达

Multi-Scale Representation of Ocean Flow Fields Euler Method Based on Map Load

欧拉法是海洋流场常用的制图方法,在电子地图中需要对欧拉法箭头符号进行动态抽稀或加密以满足用户的多尺度表达需求,确定抽稀或加密的关键比例尺是欧拉法多尺度表达的核心问题。文中将地图载负量作为欧拉法多尺度表达的评价指标,首先提出了一种欧拉法地图载负量的计算方法,分析了流场制图中较适宜的载负量区间;并由适宜载负量区间限定载负量的值,进而拟合抽稀区间内地图载负量与比例尺关系曲线,得到欧拉法多尺度表达的关键比例尺。最后,利用模糊数学中的多层次综合评判法建立了评价数学模型,并利用问卷调查法对海洋流场多尺度制图成果进行了可用性评价。

The Euler method is a common drawing method of ocean flow fields. In the electronic map, it is necessary to dynamically simplify or densify the Euler arrow symbols to meet user＇s muhi-scale representation requirements. Determining the key scale of simplifying or densifying is the core problem of muhi-scale representation of the Euler method. This paper takes the map load as the evaluation indicator of muhi-scale representation of the Euler method. Firstly, it calculates the map load of the ocean flow fields and analyzes the suitable map load intervals in flow field mapping, in order to obtain the key scale of muhi-scale representation of ocean flow fields. Then this paper limits the load by appropriate load intervals to fit the relationship between map load and scale. Then this paper establishes the evaluation mathematical model by multilevel comprehensive evaluation in fuzzy mathematics and evaluates the usability of ocean flow fields map by the questionnaire method.