Lecture-3b_Bb_1SlidePerPage

Lecture-3b_Bb_1SlidePerPage - Geographic Data Models Define...

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Geographic Data Models • Define How The Real World Is Represented In GIS – A set of constructs for describing and representing selected objects and processes in the digital environment – Different models represent the earth in different ways • There is no ‘right’ model • No one model can represent the entire earth
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Real World People Interpretation and Explanation Operational GIS Analysis and Presentation GIS Data Model link real world and operational GIS Description and Representation Line Building Pump House Hou se Street Water Line Feature Polygon Models affect what _________ can be done; provides common ground between developers and users
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Data Model Levels • Levels Of Generalization/ Abstraction • Conceptual Model – Human-oriented, conceptual description of the main types of objects and processes relevant to a problem domain • e.g. Discrete Objects vs. Continuous Fields Increasing Abstraction Reality Conceptual Model Logical Model Physical Model Human- oriented Computer -oriented
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Data Model Levels • Logical model – Implementation oriented representation of reality • e.g. Diagrams and lists, Raster vs. Vector Increasing Abstraction Reality Conceptual Model Logical Model Physical Model Human- oriented Computer -oriented
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Data Model Levels • Physical model – The actual application in a GIS upon which analysis may be performed – Describes the exact files or database tables • e.g. A Shapefile is composed of a .shp file for geometry and a .dbf file for attributes Increasing Abstraction Reality Conceptual Model Logical Model Physical Model Human- oriented Computer -oriented
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Data Models & Applications All GISystems are built upon one or more of the following Data Models, – Which, in turn, are based on Discrete/Field conceptual models and Raster/Vector logical models •C A D – Engineering design, no attributes, no topology Graphical (Non-Topological) – Simple mapping, Shapefiles Image – Image processing and analysis Raster/Grid – Spatial analysis/modeling, environmental and natural resources
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Data Models & Applications •T I N – Surface/terrain analysis/modeling •N e t w o r k – Network Analysis for transportation, hydrology, Vector/Geo-relational/Topological – Geoprocessing geometric features for cartography, social- economic and resource analysis, and modeling Object – Geoprocessing features with behavior, all types of entities and applications
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Raster Data Model • Useful for spatial analytical applications or as background maps a nominal-scale field denoting land cover class remotely sensed imagery a raster DEM
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Lecture-3b_Bb_1SlidePerPage - Geographic Data Models Define...

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