复旦大学：《数据库新技术》PPT教学课件_时空数据管理技术基础 Spatial Data Management

Spatial Data Management 2021/8/25

2021/8/25 1 Spatial Data Management

Outline Introduction of Spatial data Spatial Query Language Spatial Index structures Spatial Query Process and Optimization 2021/8/25

2021/8/25 2 Outline ◼ Introduction of Spatial data ◼ Spatial Query Language ◼ Spatial Index Structures ◼ Spatial Query Process and Optimization

Introduction of St atial data 2021/8/25

2021/8/25 3 Introduction of Spatial data

Types of spatial data Point data a Points in a multidimensional space Used when shape is not relevant (eg to represent location of detector when scale is small o E.g., Raster data such as satellite imagery, where each pixel stores a measured value o E.g., Feature vectors extracted from text 2021/8/25

2021/8/25 4 Types of Spatial Data ◼ Point Data ❑ Points in a multidimensional space ◼ Used when shape is not relevant (eg to represent location of detector) ◼ when scale is small ❑ E.g., Raster data such as satellite imagery, where each pixel stores a measured value ❑ E.g., Feature vectors extracted from text

Types of spatial data Polyline Data o A finite set of straight line segments such that each segment endpoint (called a vertex) is shared by exactly two segments, except that it may optionally have two endpoints(called the extreme points), which belong to only one segment a Polylines are classed as simple, non-simple or closed a) Simple polyline b)non-simple polyline c)closed polyline 2021/8/25

2021/8/25 5 Types of Spatial Data ◼ Polyline Data ❑ A finite set of straight line segments such that each segment endpoint (called a vertex) is shared by exactly two segments, except that it may optionally have two endpoints (called the extreme points), which belong to only one segment. ❑ Polylines are classed as simple, non-simple or closed. a) Simple polyline b) non-simple polyline c) closed polyline

Types of spatial data TWo-dimensional (polygons) o region of the plane bounded by a closed polyline a Objects have spatial extent with location and boundary Used whenever shape and/or size is also important o E.g., Buildings, roads, cities, admin districts a E.g., DB typically uses geometric approximations constructed using line segments, polygons, etc a)simple polygon b)convex polygon c)non-simple polygon d)region 2021/8/25

2021/8/25 6 Types of Spatial Data ◼ Two-dimensional (polygons) ❑ A region of the plane bounded by a closed polyline. ❑ Objects have spatial extent with location and boundary ◼ Used whenever shape and/or size is also important. ❑ E.g., Buildings, roads, cities, admin_districts ❑ E.g., DB typically uses geometric approximations constructed using line segments, polygons, etc.. a) simple polygon b) convex polygon c) non-simple polygon d) region

Types of spatial oi Spatial Range Queries o find all cities within 50 miles of madison a Query has associated region(location, boundary) a Answer includes overlapping or contained data regions Nearest-Neighbor Queries a Find the 10 cities nearest to madison a Results must be ordered by proximity Spatial Join Queries a find all cities near a lake a Expensive, join condition involves regions and proximity 2021/8/25

2021/8/25 7 Types of Spatial Queries ◼ Spatial Range Queries ❑ Find all cities within 50 miles of Madison ❑ Query has associated region (location, boundary) ❑ Answer includes overlapping or contained data regions ◼ Nearest-Neighbor Queries ❑ Find the 10 cities nearest to Madison ❑ Results must be ordered by proximity ◼ Spatial Join Queries ❑ Find all cities near a lake ❑ Expensive, join condition involves regions and proximity

Applications of Spatial data Geographic Information Systems(GIS) a E.g., ESRIS ArcInfo; OpenGIS Consortium a Geospatial information o all classes of spatial queries and data are common Computer-Aided Design/Manufacturing a Store spatial objects such as surface of airplane fuselage a Range queries and spatial join queries are common Multimedia Databases a Images video text etc. stored and retrieved by content a First converted to feature vector form high dimensionality a Nearest-neighbor queries are the most common 2021/8/25

2021/8/25 8 Applications of Spatial Data ◼ Geographic Information Systems (GIS) ❑ E.g., ESRI’s ArcInfo; OpenGIS Consortium ❑ Geospatial information ❑ All classes of spatial queries and data are common ◼ Computer-Aided Design/Manufacturing ❑ Store spatial objects such as surface of airplane fuselage ❑ Range queries and spatial join queries are common ◼ Multimedia Databases ❑ Images, video, text, etc. stored and retrieved by content ❑ First converted to feature vector form high dimensionality ❑ Nearest-neighbor queries are the most common

Operators on spatial components Operators similar to the Allen operators for time are required these must be overloaded to cope with different dimensions of spatial objects o Eg, touches(objectl, object2) Must be defined for all combinations of polyline/ polygon arguments b a C d a touches(a,b)=true touches(a, c)=false touches (c,d=true 2021/8/25

2021/8/25 9 Operators on spatial components ◼ Operators similar to the Allen operators for time are required; these must be overloaded to cope with different dimensions of spatial objects: ❑ Eg, touches(object1, object2) Must be defined for all combinations of polyline/ polygon arguments: a b a c c d touches(a,b)=true touches(a,c)=false touches(c,d)=true

Operators on spatial components As with temporal intervals the overlaps operator is particularly important a C overlaps(a,b)=true overlaps(a, c)=true 2021/8/25 10

2021/8/25 10 ◼ As with temporal intervals, the ‘overlaps’ operator is particularly important.. Operators on spatial components a b c a overlaps(a,b)=true overlaps(a,c)=true