GTECH 201 Lecture 05 Storing Spatial Data. Leftovers from Last Session From data models to data structures Chrisman’s spheres ANSI Sparc The role of GIScience.
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Presentation on theme: "GTECH 201 Lecture 05 Storing Spatial Data. Leftovers from Last Session From data models to data structures Chrisman’s spheres ANSI Sparc The role of GIScience."— Presentation transcript:
ANSI-SPARC Model for Software Development GIS are systems to model the world User Model Conceptual Model Operational Model
GIS are Systems to Model the World User Model – how we intuitively think Conceptual Model Operational Model ANSI-SPARC Model for software development
User Model Conceptual Model Operational Model ANSI-SPARC Model for software development how we systematically define ideas GIS are Systems to Model the World
User Model Conceptual Model Operational Model how we fuse systematic thinking into a technologically defined context GIS are Systems to Model the World
The ANSI/SPARC Model and Chrisman’s Spheres computer science geoinformation theory application disciplines context discipline spatial modeling conceptual modeling logical data modeling physical data modeling OPERATIONAL
Digital Maps as Models Representing a complex reality Continuous variation Spatial Data: spatial, temporal and thematic Data Models
What sort of Models are These? Raster Model - The world as regular tessellations defined by areal property Vector Model - The world as points, lines, areas and attributes….. making objects Object Model - The world as interacting entities with spatial dimensions
Vector Data Models Spaghetti model Topological models A file of spatial data that is a just a collection of co- ordinate strings. Each entity (or piece of spaghetti) is represented by one data entry. There is no topology. Topology refers to the spatial relationships between objects. The topological model represents spatial relationships such as: - length - area - connectivity - contiguity
Further Reading ANSI/SPARC model Laurini & Thompson. Fundamentals of GIS, p.357-362 Chrisman’s Spheres Chrisman, N. 1997. Exploring Geographic Information Systems Key Text for Concepts De Mers, M. 2004. Fundamentals of Geographic Information Systems. NY: John Wiley & Sons
Spatial Relationships 1 Distance Which countries contain a lake completely within their borders? Which cities are located within 25 kilometers of a river?
Spatial Relationships 2 Intersection Which countries have a river that intersects their border?
Spatial Relationships 3 Adjacency Which countries share a border with Russia?
Spatial Relationships 4 Containment Which countries contain a lake completely within their borders?
GIS as a Process 1 1.Capture data 2.Store data 3.Query data 4.Analyze data 5.Display data 6.Present data
1.Ask a geographic question 2.Acquire geographic data 3.Explore geographic data 4.Analyze geographic information 5.Act on geographic knowledge GIS as a Process 2
Summary A GIS organizes and stores information about the world as a collection of thematic layers. Each layer contains features with the same shape and attributes, all located within a common geographic area. Each feature is assigned a unique numerical identifier and is characterized by a unique location in space and a corresponding record in a table. Features can be stored in a GIS as three primary shapes: points, lines, or polygons. Features have spatial relationships with other features, and with a GIS you can find features based on their spatial relationships. The geographic inquiry process provides a framework for solving problems with GIS.