Introdução to Geoinformatics: vector geometries

Vector geometries

Vector geometries Arcs and nodes Polygons

Vector geometries fonte: Universidade de Melbourne

Vector Model: Lines vertex node Lines start and end at nodes line #1 goes from node #2 to node #1 Vertices determine shape of line Nodes and vertices are stored as coordinate pairs

Vector Model: Polygons Polygon #2 is bounded by lines 1 & 2 Line 2 has polygon 1 on left and polygon 2 on right

Types of topology source: ESRI

Planar enforcement All the space on a map must be filled Any point must fall in one polygon alone Polygons must not overlap

Vector geometries Island Points

Topology: polygon-polyline source: ESRI

Topology: polygon-polyline Shapefile polygon spatial data model less complex data model polygons do not share bounding lines

Topology: the OGC model source: John Elgy

What’s the use of a polygon? Census tracts in São José dos Campos

Topology: arc-node-polygon source: ESRI

Topology: arc-node-polygon source: GIS Basics (Campbell and Chin, 2012)

Vectors and table Duality between entre location and atributes Lots geoid owner address cadastral ID 22 Guimarães Caetés 768 250186 23 22 23 Bevilácqua São João 456 110427 24 271055 Ribeiro Caetés 790

Duality Location - Attributes Praia de Boiçucanga Praia Brava Exemplo de Unidade Territorial Básica - UTB

Geometrical operations Point in Polygon = O(n)

Geometrical operations Line in Polygon = O(n•m)

Topological relationships

Topological relationships Disjoint Point/Point Line/Line Polygon/Polygon

Topological relationships Touches Point/Line Point/Polygon Line/Line Line/Polygon Polygon/Polygon

Topological relationships Crosses Point/Line Point/Polygon Line/Line Line/Polygon

Topological relationships Overlap Point/Point Line/Line Polygon/Polygon

Topological relationships Within/contains Point/Point Point/Line Point/Polygon Line/Line Line/Polygon Polygon/Polygon

Topological relationships Equals Point/Point Line/Line Polygon/Polygon

Topological relations Interior: A◦ Exterior: A- Boundary: ∂A

Topological Concepts Interior, boundary, exterior Green is A interior Let A be an object in a “Universe” U. Green is A interior Red is boundary of A Blue –(Green + Red) is A exterior U A

4-intersections disjoint contains inside equal             disjoint contains inside equal               meet covers coveredBy overlap

OpenGIS: 9-intersection dimension-extended topological operations Relation disjoint meet overlap equal 9-intersection model

Example Consider two polygons A - POLYGON ((10 10, 15 0, 25 0, 30 10, 25 20, 15 20, 10 10)) B - POLYGON ((20 10, 30 0, 40 10, 30 20, 20 10))

9-Intersection Matrix of example geometries I(B) B(B) E(B) I(A) B(A) E(A)

Specifying topological operations in 9-Intersection Model Question: Can this model specify topological operation between a polygon and a curve?

9-Intersection Model

Examples of functions defined by SFSQL

DE-9IM: dimensionally extended 9 intersection model

9-Intersection Matrix of example geometries I(B) B(B) E(B) I(A) B(A) E(A)

DE-9IM for the example geometries I(B) B(B) E(B) I(A) 2 1 B(A) E(A)