Pro Spatial with SQL Server 2012

Pro Spatial with SQL Server 2012 Alastair Aitchison ULB Darmstadt Illllllill 17711989 Apress*

Contents Contents at a Glance Foreword About the Author About the Technical Reviewer Acknowledgments Introduction v xxi xxii xxiii xxiv...xxv II Chapter 1: Spatial Reference System 1 What Is a Spatial Reference System?,...1 Modeling the Earth 2 Approximating the Geoid, 3 Regional Variations in Ellipsoids 4 Realizing a Reference Ellipsoid Model with a Reference Frame 5 Geographic Coordinate Systems...6 Geographic Units of Measurement.7 Defining the Origin of a Geographic Coordinate System 7 Projected Coordinate Systems 8 Creating Map Projections 8 Hammer-Aitoff Projection 9 Mercator Projection : 10 Equirectangular Projection 11 Universal Transverse Mercator Projection 12 Projection Parameters 13 Projected Units of Measurement 14 Putting It All Together: Components of a Spatial Reference System 15 Spatial Reference Identifiers (SRIDs) 16 Weil-Known Text of a Spatial Reference System 17 Contrasting a Geographic and a Projected Spatial Reference 18 Summary 19 Vll

CONTENTS Chapter 2: Spatial Features 21 Geometry Hierarchy 21 Interiors, Exteriors, and Boundaries 23 Points 24 Example Point Usage 24 Defining a Point 25 Defining Points in 3- and 4-Dimensional Space 26 Characteristics of Points 27 LineStrings 27 Example LineString Usage 27 Defining a LineString 28 Characteristics of LineStrings 29 LineStrings and Self-Intersection 30 CircularStrings 30 Example CircularString Usage ;rr....30 Defining a CircularString 31 Characteristics of CircularStrings 33 Drawing Complete Circles 33 Choosing Between LineString and CircularString.34 CompoundCurves 34 Example CompundCurve Usage 35 Defining a CompoundCurve 35 Characteristics of CompoundCurves 36 Polygons... 36 Example Polygon Usage 36 Exterior and Interior Rings 37 Defining a Polygon 38 Characteristics of Polygons 38 CurvePolygons 39 Example CurvePolygon Usage 39 Defining a CurvePolygon 40 Characteristics of CurvePolygons 41 Vlll

icontents MultiPoints 41 Example Multipoint Usage 41 Defining A Multipoint 42 Characteristics of MultiPoints 43 Many Single Points, or One Multipoint? 43 MultiLineStrings 43 Example MultiLineString Usage 43 Defining a MultiLineString 44 Characteristics of MultiLineStrings 45 MultiPolygons 45 Example MultiPolygon Usage 45 Defining a MultiPolygon 46 Characteristics of MultiPolygons 46 GeometryCollections, 46 Example GeometryCollection Usage...^ 46 Defining a GeometryCollection 46 Characteristics of Geometry Collections ".. 47 FullGlobe 47 Defining a FullGlobe 47 Characteristics of the FullGlobe geometry are as follows 47 Empty Geometries 48 Defining an Empty Geometry 48 Characteristics of Empty Geometries 49 Choosing the Correct Geometry 49 Summary 49 II Chapter 3: Spatial Datatypes 51 SQLCLR Foundations 52 Methods and Properties 53 Static Methods 54 Instance Methods 54 Properties 55 Spatial Libraries 56 IX

I CONTENTS The geography Datatype 57 Spatial Reference Systems for the geography Datatype 58 Correct Ring Orientation for geography Polygons 60 The geometry Datatype 62 Spatial Reference Systems for the geometry Datatype 64 Storing Nongeodetic Data...65 The Insignificance of Ring Orientation in a geometry Polygon 65 Comparing geography and geometry Datatypes 66 Consistency 66 Accuracy 67 The End(s) of the World 67 Presentation 69 Performance 70 OGC Standards Compliance... 70 General Rules.-.... 71 Storage Requirements 71 Internal Data Structure : 72 Converting Between Datatypes 73 Creating Spatially Enabled Tables 74 Enforcing a Common SRID...75 Summary 76 if Chapter 4: Creating Spatial Data 77 Creating Spatial Data from Well-Known Text 77 Choosing a WKT Static Method 78 Passing WKT to the Method 78 Retrieving the WKT Representation of an Instance 81 Creating Spatial Data from Well-Known Binary 81 Choosing a WKB Static Method 82 Representing an Existing Geometry as WKB 84 Creating Spatial Data from Geometry Markup Language 85 GeomFromGmlO The Only GML Static Method 86 The GML Namespace 86 Representing an Existing Geometry as GML 87

S CONTENTS Creating Spatial Data from Dynamically Generated WKT 88 Creating Spatial Data Using the Builder Classes 91 Configuring a.net Console Application for Spatial Data 91 Constructing a Simple Point 93 Building Polygons with Multiple Rings 96 Creating Geometry Collections 97 Building Curved Geometries 98 Programmatically Defining Three- and Four-Dimensional Geometries 99 Summary...99 i Chapter 5: Importing Spatial Data 101 Sources of Spatial Data 101 Importing Tabular Spatial Data 102 Importing the Text File : 105 Creating a Computed Column 106 Populating a Noncomputed Column 107 Comparing Computed, Noncomputed, and Persisted Columns 108 Importing Data Using 0GR20GR 109 Obtaining and Installing the GDAL/OGR Library... 109 0GR20GR Basic Syntax 110 Importing ESRI Shapefile Data 110 Obtaining Sample Shapefile Data 111 Loading the Data 112 Assigning an Output SRID 113 Another Example: Specifying Layer Creation Options 116 Importing Maplnfo Data 118 Obtaining Sample Maplnfo Data 118 Determining the SRID 119 Loading the Data 120 Reprojecting Data During Import 121 Exporting Spatial Data from SQL Server 122 Keyhole Markup Language 122 Exporting from SQL Server to KML with 0GR20GR 123 XI

!CONTENTS Spatial ETL Using SQL Server Integration Services 125 Importing Point Data Using a Custom Script Component 125 Creating a New SSIS Project 125 Creating the Text File Connection 125 Creating the SQL Server Connection 127 Adding a New Dataflow Task and Specifying the Data Source 128 Creating the Script Component 128 Specifying the Destination 132 Running the SSIS package 134 Using Third-Party Source Components 135 CodePlex SSIS Shapefile Source 135 SafeFME 135 Summary 136 Chapter 6: Geocoding 139 The Bing Maps Geocoding Service....139 Obtaining a Bing Maps Key..T. 140 Calling the Bing Maps REST Locations API.-. 141 Creating a.net Geocoding Assembly 143 Creating a New Project 143 Configuring the Project 144 Adding a Reference to Microsoft.SqlServer.Types.dll 145 Adding a Simple Geocoding Function 146 Creating a Geocoding UDF Wrapper 148 Compiling the Assembly 149 Configuring the Database 150 Enabling CLR Support 150 Setting Security Permissions 150 Importing the Assembly 151 Creating the Geocode Function 152 Using the Geocode Function 153 Creating a Geocoding TVF Wrapper 154 Asynchronous and Batch Geocoding 158 Reverse Geocoding 159 Summary 161 Xll

CONTENTS il Chapter 7: Precision, Validity, and Errors 163 Precision 163 Storage Precision 164 Practical Implications of Fixed Binary Precision 165 geometry Precision 165 geography Precision 165 Balancing Precision Against Transmission Size 168 Calculation Precision 171 Precision and Equality 174 Validity 175 Testing Whether a Geometry Is Valid 177 Finding Out Why a Geometry Is Invalid 177 Making an Object Valid 178 Handling Errors 181 Dissecting a SQLCLR Exception 181 Error-Handling Mechanisms :Z 183 Summary 185 II Chapter 8: Transformation and Reprojection 187 Datum Transformation 187 Transformation Algorithms 190 Coordinate Offsets (Two Parameters) 190 Molodensky Transformation (Five Parameters) 191 Helmert Transformation (Seven Parameters) 192 Transforming to and from WGS84 193 Projection, Unprojection, and Reprojection 194 Performing Manual Calculations 197 Creating a Reusable Spatial Conversion Library 198 Storing Transformation Parameters 198 Compiling the Proj.NET Assembly for SQL Server 200 Creating Transformation Sinks 202 Registering the Transformation Assembly and Functions 207 Transforming Spatial Data in T-SQL 208 Architecture and Design Considerations 209 Summary 210 Xlll

i CONTENTS Chapter 9: Examining Spatial Properties...211 Property and Method Syntax A Reminder 211 Examining the Type of Geometry Used to Represent a Feature 212 Returning the Type of Geometry 212 Testing the Type of Geometry 213 Determining the Number of Dimensions Occupied by a Geometry 214 Testing for OGC Properties 217 Testing for Simplicity 217 Testing if a Geometry Is Closed 219 Testing Whether a LineString or Curve Is a Ring 221 Counting the Number of Points in a Geometry 221 Returning the Number of Points in a Geometry 222 Testing Whether a Geometry Is Empty 223 Returning Individual Points from a Geometry 224 Retrieving a Point by Index C. 224 Returning the Start and End Point of a Geometry 226 Determining the Center of a Geometry 227 Calculating the Centroid of a geometry Instance 227 Calculating the Envelope Center of a geography Instance 228 Returning an Arbitrary Point from a Geometry 230 Returning Coordinate Values 231 Returning geometry Coordinates 231 Returning geography Coordinates 232 Returning Extended Coordinate Values 232 Properties Describing the Extent of a Geometry 233 Calculating the Boundary of a Geometry 233 Calculating the Envelope of a Geometry 235 Calculating the Bounding Circle of a geography Instance 237 Properties Related to Surfaces..239 Isolating the Exterior Ring of a Geometry Polygon 239 Counting the Interior Rings of a geometry 241 Isolating an Interior Ring from a geometry Polygon 242 Counting the Rings in a geography Polygon 243 XIV

CONTENTS Isolating a Ring from a geography Polygon 244 Properties Related to GeometryCollections 245 Counting the Number of Geometries in a Collection 246 Retrieving an Individual Geometry from a Collection 247 Calculating Metrics 248 Measuring the Length of a Geometry 248 Calculating the Area Contained by a Geometry 249 Setting or Retrieving the Spatial Reference Identifier (SRID) 251 Summary 252 I I Chapter 10: Modification and Simplification 253 Simplifying a Geometry 253 The Douglas-Peucker Algorithm 254 The ReduceO Method 255 Converting Curves to Lines 256 Linearization with STCurveToLineO 256 Approximate Linearization r. 257 Reorienting a geography Polygon 258 Densification... 260 Buffering 264 Creating a Buffer 264 Creating a Simpler Buffer 266 Creating a Curved Buffer 267 Creating the Convex Hull of a Geometry 269 Summary 271 C Chapter 11: Aggregation and Combination 273 Creating a Union of Two Items of Spatial Data 273 Appending One Geometry onto Another 276 Subtracting One Geometry from Another 277 Determining the Unique Parts of Two Geometries 281 Defining the Intersection Between Two Geometries 282 Aggregating Columns of Spatial Data 284 UnionAggregate 286 XV

II CONTENTS EnvelopeAggregate 287 CollectionAggregate 287 ConvexHullAggregate 288 Combining Spatial Result Sets 288 Joining Tables Using a Spatial Column 291 Summary 292 Chapter 12: Testing Spatial Relationships 293 Calculating the Distance Between Two Geometries 293 Finding Nearest Neighbors: Basic Approach 295 Finding Nearest Neighbors Using a Spatial Index 296 Finding Nearest Neighbors Within a Fixed Search Zone 298 Finding Nearest Neighbors with an Expanding Search Zone 299 Nearest Neighbor Query Plan Comparison 301 Calculating the Shortest Path Between Two Geometries 304 Testing for Intersection 308 Accurate Testing for Intersection.-. 308 Approximate Testing for Intersection 310 Testing for Disjointness 313 Identifying Specific Types of Intersection.314 Determining Whether One Geometry Crosses Another 314 Finding Out Whether Two Geometries Touch 317 Testing for Overlap 318 Testing Whether One Geometry Is Contained Within Another 320 Testing Whether One Geometry Contains Another 321 Defining Custom Relationships Between Geometries 322 Summary. 325 Chapter 13: Clustering and Distribution Analysis 327 SQL Server's Spatial Histogram Procedures 328 sp_help_spatial_geometry_histogram 328 sp_help_spatial_geography_histogram 331 Creating a Customized Distribution Analysis 335 Creating a Regular Grid 336 XVI

CONTENTS Creating a Bullseye Grid 340 Defining a Custom Pattern of Cells 342 k-means Clustering 344 Summary 352 ii Chapter 14: Route Finding 353 Graph Theory 353 Modeling a Street Network 354 Defining the Street Names 355 Defining Street Segments (Edges) 356 Viewing the Network 356 Brute-Force Routing int-sql 357 Tracing The Route 361 Avoiding Cycles 362 Allowing for Direction 364 A*: A More Efficient Routing Algorithm? 365 Heuristics.'..365 Restructuring the Data 367 Traversing Across the Network 369 Putting It All Together 373 Testing It Out 377 Optimizing the Code and Further Enhancements 378 The Traveling Salesman Problem...379 Harnessing the Bing Maps Routing Service 382 Summary 386 ii Chapter 15: Triangulation and Tesselation 387 The Importance of Triangles...387 Triangulation 388 The Delaunay Triangulation 389 Calculating the Delaunay Triangulation 390 An SQLCLR Triangulation Procedure 392 Data Structures 392 Setting Up the Points 394 xvn

3 CONTENTS Creating the Supertriangle 395 Adding Points to the Triangulated Mesh 396 Outputting the Results 398 Registering and Testing the Function 399 Creating 3D Surface Models.401 Adapting the Triangulation Code into 3D 401 A Practical Example: Creating a 3D Surface from LIDAR Data 402 Visualizing a 3D Mesh in WPF 404 Creating Alpha Shapes (Concave Hulls).. 407 Adapting the Triangulation Code to Create Alpha Shapes 408 A Practical Example: Calculating the Outline of Massachusetts 408 Small Alpha Values 409 Large Alpha Values 410 Getting the Alpha Value "Just Right" 410 Voronoi Tessellations 412 Adapting the Triangulation Code to Create a Voronoi Tesselation 413 A Practical Example: Outbreaks of Cholera in Victorian London 414 Summary 418 Chapter 16: Visualization and User Interface..419 The SSMS Spatial Results Tab... 419 Add a Buffer to Points 421 Create a Base Layer Against Which to Display Your Data 421 Customize the Display 423 Thematic Mapping with Google Earth. 425 Getting the Data 426 Creating a Color Range 427 Exporting to KML 428 Styling the KML File 428 Taking It Further 431 Limitations 432 Creating a Web Map Interface with Bing Maps 433 Create the SQL Server Table and Stored Procedure 433 XV1U

! CONTENTS Creating the Web Application 434 Defining the HTML/Javascript 435 Retrieving JSON Data from SQL Server to the Webpage 440 Taking It Further 443 Summary 444 Chapter 17: Reporting Services 445 Creating a Simple Report Map 445 Creating the Report Project 446 Defining the SQL Connection 447 Creating a New Report 448 Adding a Map to the Report 448 Specify a Data Source 449 Design the Query 452 Previewing the Report ; 455 Customizing the Map Viewport.C 455 General Options 456 Center and Zoom 457 Optimization 458 Fill, Border, and Shadow 458 Adding an Analytic Dataset...459 Applying a Styling Rule 462 General Settings 463 Distribution Options 463 Legend 465 Adding a Bing Maps Tile Layer 466 Assigning Actions to Map Elements 467 Limitations of the SSRS Map Control 469 Summary 470 Ii Chapter 18: Indexing 471 The Need for a Spatial Index...471 How Does a Spatial Index Work? 472 The Primary and Secondary Filter 472 XIX

CONTENTS The Grid Structure of a Spatial Index 472 Refining the Grid 476 The Auto Grid 479 Optimization Rules in a Multilevel Grid Index 479 Covering Rule 480 Deepest-Cell Rule 481 Cells-Per-Object Rule 481 Creating a Spatial Index in T-SQL 481 Analysing How the Index Is Used 483 Tesselation Information 486 Primary Filter Selectivity 486 Internal Filtering 487 Secondary Filtering and Output 487 Efficiency Measures 487 Creating a geography Index 488 Designing Queries to Use a Spatial Index. 489 Supported Methods.'. 489 Correct Syntax and Query Form 490 Checking if a Spatial Index Is Being Used 491 Adding an Index Hint.493 Optimizing an Index 493 Grid Resolution 493 Bounding Box 494 Cells per Object 495 Performance Comparison... 496 Summary 497 Appendix 499 Index 519 XX