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Published byOtávio Guimarães Damásio Modified over 6 years ago
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Introdução to Geoinformatics: vector geometries
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Vector geometries
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Vector geometries Arcs and nodes Polygons
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Vector geometries fonte: Universidade de Melbourne
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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
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Vector Model: Polygons
Polygon #2 is bounded by lines 1 & 2 Line 2 has polygon 1 on left and polygon 2 on right
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Types of topology source: ESRI
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Planar enforcement All the space on a map must be filled
Any point must fall in one polygon alone Polygons must not overlap
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Vector geometries Island Points
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Topology: polygon-polyline
source: ESRI
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Topology: polygon-polyline
Shapefile polygon spatial data model less complex data model polygons do not share bounding lines
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Topology: the OGC model
source: John Elgy
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What’s the use of a polygon?
Census tracts in São José dos Campos
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Topology: arc-node-polygon
source: ESRI
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Topology: arc-node-polygon
source: GIS Basics (Campbell and Chin, 2012)
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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
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Duality Location - Attributes
Praia de Boiçucanga Praia Brava Exemplo de Unidade Territorial Básica - UTB
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Geometrical operations
Point in Polygon = O(n)
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Geometrical operations
Line in Polygon = O(n•m)
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Topological relationships
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Topological relationships
Disjoint Point/Point Line/Line Polygon/Polygon
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Topological relationships
Touches Point/Line Point/Polygon Line/Line Line/Polygon Polygon/Polygon
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Topological relationships
Crosses Point/Line Point/Polygon Line/Line Line/Polygon
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Topological relationships
Overlap Point/Point Line/Line Polygon/Polygon
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Topological relationships
Within/contains Point/Point Point/Line Point/Polygon Line/Line Line/Polygon Polygon/Polygon
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Topological relationships
Equals Point/Point Line/Line Polygon/Polygon
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Topological relations
Interior: A◦ Exterior: A- Boundary: ∂A
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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
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4-intersections disjoint contains inside equal
disjoint contains inside equal meet covers coveredBy overlap
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OpenGIS: 9-intersection dimension-extended topological operations
Relation disjoint meet overlap equal 9-intersection model
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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))
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9-Intersection Matrix of example geometries
I(B) B(B) E(B) I(A) B(A) E(A)
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Specifying topological operations in 9-Intersection Model
Question: Can this model specify topological operation between a polygon and a curve?
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9-Intersection Model
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Examples of functions defined by SFSQL
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DE-9IM: dimensionally extended 9 intersection model
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9-Intersection Matrix of example geometries
I(B) B(B) E(B) I(A) B(A) E(A)
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DE-9IM for the example geometries
I(B) B(B) E(B) I(A) 2 1 B(A) E(A)
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