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# GIS Information Models III.

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Vector Data Model: Spaghetti. From Fundamentals of Geographic Information Systems, Demers ... Shapefile in the middle of spaghetti & topological information structures ...
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﻿GIS Data Models III GEOG 370 Instructor: Christine Erlien

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Representing Geographic Space: Vector Data Structures Represent spatial areas expressly Relationships between substances certain Space between geographic elements not put away

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Vector Data Models Multiple information models Examination of connections Between variables in 1 map Among variables in different maps Data models Spaghetti models Topological models Vector chain codes

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Vector Data Model: Spaghetti Simplest information structure One-to-one interpretation of graphical picture Doesn\'t record topology  connections inferred instead of encoded Each element is a solitary bit of spaghetti Point Line Area short longer accumulation of line fragments Each element is a solitary record, coded as variable-length strings of (X,Y) direction sets Boundaries shared by two polygons  put away twice

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Vector Data Model: Spaghetti From Fundamentals of Geographic Information Systems , Demers (2005)

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Vector Data Model: Spaghetti Measurement & investigation troublesome All connections among items must be ascertained freely Relatively productive for cartographic showcase CAC Plotting: quick www.gis.niu.edu/Cart_Lab_03.htm

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Vector Data Model: Topological Topology: Spatial connections between focuses, lines & polygons Topological models record nearness data into information structure Line sections have starting & finishing Link: Line portion Node: Point that connections two or more lines Identifies that point as the starting or consummation of line Left & right polygons put away unequivocally

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Vector Data Model: Topological From An Introduction to Geographic Information Systems , Heywood et al. (2002)

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Topological Data Models Multiple models GBF/DIME (geographic base record/double autonomous guide encoding) TIGER (topologically coordinated geographic encoding and reference framework) POLYVRT (POLYgon conVERTer)

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Topological Data Models: GBF/DIME Created by U.S. Statistics Bureau Both road addresses & UTM arranges characterized for every connection Topology + heading Left/right From/to From Fundamentals of Geographic Information Systems , Demers (2005)

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Topological Data Models: TIGER Point Area Designed for use with the 1990 U.S. Statistics Block-level maps Points, lines & zones unequivocally tended to Census squares can be recovered straightforwardly by piece number Coordinates Line From Fundamentals of Geographic Information Systems , Demers (2005)

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Topological Data Models: POLYVRT Entities put away independently yet connected to each other through pointers Chains: Collections of line fragments with directional data (from-to, left/right) From Fundamentals of Geographic Information Systems , Demers (2005)

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ArcGIS/Arcview\'s Shapefile Comprised of 3 record sorts *.shp contains organizes *.shx is a file document *.dbf is a trait document in dbase design Where is topology? Not expressly put away Created on-the-fly Shapefile  in the middle of spaghetti & topological information structures

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Compacting Vector Data Models Compact information to decrease stockpiling Freeman-Hoffman chain codes Each line portion Directional vector Length Non-topological Analytically constrained  limits convenience to capacity, recovery, yield works Good for separation & shape counts, plotting

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Vector Model to Represent Surfaces: TIN permits us to record topographic information as focuses in a standard or unpredictable lattice.

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Vector Model to Represent Surfaces: TIN From Geographic Information Systems & Science , Longley et al. (2005)

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Vector GIS: Hybrid & Integrated Systems Hybrid framework Links realistic information structures with DBMS Efficiently oversee both representation & quality information Allows raster & vector information sorts From Fundamentals of Geographic Information Systems , Demers (2005)

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Vector GIS: Hybrid & Integrated Systems Integrated framework Entities\' direction information put away as social table Topological information put away as independent table in same database Attributes can be Stored in same tables as realistic elements Stored as discrete tables & connected socially GIS more firmly coordinated with DBMS than in cross breed framework

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Vector GIS: Object-Oriented Database Management Systems Emerging as a contrasting option to half and half or incorporated models Extends the coordinated model by fusing a spatial question dialect Objects acquire properties from the class of items that they have a place with Variable sorts & operations specific to that class Example: ArcGIS\' geodatabase Shift from past crossover introduction

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