第4章空间分析概念框架(管理).pdf

Geographic Information System Chap 4. Conceptual Framework for Spatial Analysis April, 2012 Geographic Information System 4.1 Basic Primitives 4.2 Spatial Relationships 4.3 Spatial Statistics • Place eg. A: 1118 W 25TH ST, Los Angeles, 90007 B: Los Angeles Convention Center The basis of rigorous and precise definition of place is a coordinate system: latitude/longitude eg. A: (34.033572,-118.284656) B: (34.043219,-118.269850) • Attributes : A data item associated with an individual object (record) in a spatial database Explicit attributes: elevation; name Implicit attributes: polyline length, polygon centroid. Example Example • Objects Points as pairs of coordinates, in latitude/longitude or some other standard system Lines as ordered sequences of points connected by straight lines Areas or volumes as ordered rings of points, also connected by straight lines to form polygons. How to define the distance between LA and LV??? •Fields denotes a quantity that can be theoretically assigned to any point of space. Two ways of thinking about attributes on the Earth‟s surface: Continuous fields (sometimes discontinuous field) Discrete objects Discrete objects Continuous fields Surface Continuous fields 1 8 4 4 2 5 8 20 4 1 11 2 26 1 6 ContoursContours 1 6 8