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Data Models in Commercial GIS

SystemsE. Hoel, page 215-219

CSCI 5715 – Fall 2014

10/14/2014

Sameera ShahShyam Sundar Somasundaram

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Relevance

Week 2 - Spatial Concepts and Data Models ( Ch. 2)

Categorization

Commercial GIS Data Models

Raster Vector

Spaghetti Topology Network

Directed Undirected

DEM

Raster DEM

TIN (Vector)

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Raster Model

Stores data in matrix form

Useful for data varying continuously e.g. aerial photograph

Single images

Raster Catalog Collection of rasters

Source: https://courses.washington.edu/gis250/lessons/introduction_gis/spatial_data_model.html

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Vector Model (1/4)

Co-ordinate based data model

Useful for storing data that has discrete boundaries

Classified into further subtypes Spaghetti Network Topological

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Spaghetti Model (2/4)

Simple Data Model or Spaghetti Plot

Geometric representations have no explicit relationship

E.g. Hurricane model

Source: https://ecodatarecovery.wordpress.com/tag/data-backup/

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Network Model (3/4)

One dimensional collection of point (junction) and line(edges) features

Directed e.g. water flow modeling Hydrologic networks Utility networks

Undirected e.g. transportation network

Source: http://www.dublintunnel.ie/images/routes/dublin_map.gif

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Topology Models (4/4)

Control geometric relationships

Collection of nodes, arcs, faces and their inter relationships

E.g. United States Census geographic data

Source: http://docs.oracle.com/cd/B19306_01/appdev.102/b14256/sdo_topo_concepts.htm

Point features (traffic signs), shown as dark circles: S1, S2, S3, and S4Linear features (roads or streets), shown as dashed lines: R1, R2, R3, and R4

Area features (land parcels), shown as rectangles: P1, P2, P3, P4, and P5

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Digital Elevation Model (DEM)

Represent the surface topography of the earth

Built from remote sensing data or survey methods

E.g. perform line-of-sight for cell phone

Classified based on type of source data as: Raster DEM TIN DEM

Source: http://www.temis.nl/data/topo/gtopo30tiles.gif

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TIN DEM

A.k.a Vector based surface model

Contiguous non – overlapping triangles

Nodes, edges, triangles

Facilitates surface modeling

Source http://wtlab.iis.u-tokyo.ac.jp/~wataru/lecture/rsgis/rsnote/cp6/6-10-2.gif

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Future Directions

Available data for specific times /dates

Augment existing data models to support temporal data

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References

Data Models in Commercial GIS Systems, E. Hoel, page 215-219

Spatial Databases: A Tour, S. Shekhar and S. Chawla, Prentice Hall, 2003

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