The document provides an overview of GIS data models, focusing on vector and raster data models, their structures, and implications for data abstraction. It discusses key concepts such as points, lines, and polygons, as well as topology and the importance of understanding relationships in spatial data. Additionally, the document covers file formats, examples of GIS applications, and references for further reading.

1. Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

2. GIS Data Models
GIS Data Models
Vector Data Models
Vector Data Models
Vector File Formats
Vector File Formats
Raster Data Models
Raster Data Models
Raster File Formats
Raster File Formats
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

3. Data Abstraction
Data Abstraction
• To use GIS the real world must be
abstracted into points, lines, polygons,
raster cells, and attribute values
• Class examples may use common object
that most people will understand. If you
understand how to abstract common
objects you will be able to apply the same
method to object in your field
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

4. What is Vector Data
What is Vector Data
• Vector Data uses Points and their (X,Y)
coordinates to represent spatial features
• Points, Lines and Polygons
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

5. Points
Points
• A point is a 0 dimensional object and has
only the property of location (x,y)
• Points can be used to Model features such
as a well, building, power, pole, sample
location ect.
• Other name for a point are vertex, node, 0-
cell
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

6. Lines
Lines
• A line is a one-dimensional object that has the
property of length
• Lines can be used to represent road, streams,
faults, dikes, maker beds, boundary, contacts
etc.
• Lines are also called an edge, link, chain, arc, 1-
cell
• In an ArcInfo coverage an arc starts with a node,
has zero or more vertices, and ends with a node
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

7. Figure 4.3 p58 Bernhardsen
Figure 4.3 p58 Bernhardsen
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

8. Polygons
Polygons
• A polygon is a two-dimensional object with
properties of area and perimeter
• A polygon can represent a city, geologic
formation, dike, lake, river, ect.
• Other name for polygons face, zone 2-cell
• Scale matters
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

9. Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

10. Data Abstraction Discussion
Data Abstraction Discussion
• If you do not understand this the rest of
GIS will not make sense
• Scale Matters
• Intended use Matters
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

11. Examples
Examples
• Trees
• Dikes
• Roads
• Rivers
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

12. Topology
Topology
• A set of rules on how objects relate to
each other
• Major difference in file formats
• Higher level objects have special topology
rules
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

13. Topology Definition
Topology Definition
• The Science of mathematics of relationships
used to validate the geometry of vector entities,
and for operations such as network tracing and
tests of polygon adjacency.
• The study of geometric properties that do not
change when the forms are bent, stretched or
under go similar geometric transformations.
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

14. Figure 2-9 GIS Fundamentals, Bolstad
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

15. Planar Enforcement
Planar Enforcement
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

16. Why Topology Matters
Why Topology Matters
• Error Detection
open polygons
unlabeled polygons
slivers
polygons that cannot exist next to each
other
• Network Modeling
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

17. Show Placitas
Show Placitas
• Arc Node Topology
– Cover#
– Lpoly# and Rpoly#
– Tnode fnode
• Label errors
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

18. Higher Level Object
Higher Level Object
• Regions
• Networks
• TIN – Triangulated irregular network
• Dynamic Segmentation
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

19. Regions
Regions
Overlapping areas with different attributes
e.g.Fire history
Disconnected areas with the same attributes
e.g. Hawaii
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

20. Networks
Networks
• Road systems, power grids, water supply
sewerage systems, drainage network
• Continuous connected networks
• Rules for displacement in a network
• Attribute value accumulations due to
displacements
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

21. TIN
TIN
• Vector Surface Model
• Triangulated Irregular Network
• A set of nonoverlapping triangles each
with a constant gradient
• A TIN can honor original input elevations
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

22. Dynamic Segmentation
Dynamic Segmentation
• Combines a line coverage with a linear
reference system
• Has event tables for point events and
linear events
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

23. Fig 3.13 p52 Chang
Fig 3.13 p52 Chang
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

24. Examples and Demo
Examples and Demo
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

25. Shape Files
Shape Files
• Nontopological
• Advantages no overhead to process
topology
• Disadvantages polygons are double
digitized, no topologic data checking
• 3 files .shp .shx .dbf
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

26. Coverages
Coverages
• Original ArcInfo Format
• Directory With Several Files
• Database Files are stored in the Info
Directory
• Uses Arc Node Topology
– Planer Enforcement
– Connectivity
– Adjacency
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

27. GeoDatabase
GeoDatabase
• New GIS Format at ArcGIS 8.0
• Two Types
– Personal Geodatabase
– Microsoft access 2000 database
– SDE GeoDatabase
– Multi-user
– Can connect to many RDBMS
• Oracle, SQL server, Informix
• File are stored in the format native to the RDBMS
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

28. Box 3.5 Geographic Information
Box 3.5 Geographic Information
Systems, Chang 04 p. 55
Systems, Chang 04 p. 55
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

29. GeoDatabase
GeoDatabase
• Shapes are similar to shape files
• Object-oriented model not a Geo-relational
• There are 25 topology rules that can be
used to relate different layers
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

30. Raster Data Model
Raster Data Model
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

31. Figure 3:1 Getting Started with
Figure 3:1 Getting Started with
Geographic Information Systems,
Geographic Information Systems,
Clarke (2003) p. 91
Clarke (2003) p. 91
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

32. Grid Properties
Grid Properties
• Each Grid Cell holds one value even if it is empty.
• A cell can hold an index standing for an attribute.
• Cell resolution is given as its size on the ground.
• Point and Lines move to the center of the cell.
• Minimum line width is one cell.
• Rasters are easy to read and write, and easy to
draw on the screen.
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

33. Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

34. Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

35. Raster Pyramids
Raster Pyramids
• With out pyramids the entire raster must
be read for each screen draw
• Pyramids store reduced resolution dataset
files .rrd to increase the speed of screen
draws
• When you add a raster to ArcMap if
pyramids do not exist you can create them
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

36. Raster Resampling
Raster Resampling
• Nearest Neighbor
– Closest cell
– Continuous and Discrete data
• Bilinear interpolation
– Average of nearest 4 cells
– Continuous data only
• Cubic Convolution
– Average of nearest 16 cells
– Continuous data only
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

37. Quad Tree Compression
Quad Tree Compression
• May be use to get variable resolution for
imagery in the National Map
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

38. Figure 4.35 Geographic Information Systems and Introduction,
Bernhardsen (2001), p. 87
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

39. C. Dana Tomlin, Geographic Information Systems and Cartographic
C. Dana Tomlin, Geographic Information Systems and Cartographic
Modeling (1990), P. 44
Modeling (1990), P. 44
• “Yes raster is faster, but raster is vaster,
and vector just seems more corrector”
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

40. Images are a form of raster data
Images are a form of raster data
• ArcGIS can use many common image
formats
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

41. Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

42. Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

43. Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

44. Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

45. Industry Standard Data Models
Industry Standard Data Models
• Some Industries have created standard
data models
• It is a good idea to use a standard model
to promote sharing of data
• Some data models can be very complex
• Complex models require custom tools to
be useful
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

46. Dr. Rapanwad S. R.
Dr. Rapanwad S. R.

47. References
References
• Getting Started with Geographic Information
Systems 4th
Edition, Clark (2003)
• Geographic Information Systems an Introduction
3rd
Edition, Bernhardsen (2002)
• Introduction to Geographic Information Systems
2nd
Edition, Chang (2004)
• GIS Fundamentals, Bolstad (2002)
• ArcGIS 8.3 Desktop Help
• Using GRID with ArcInfo version 7 ESRI
Dr. Rapanwad S. R.
Dr. Rapanwad S. R.