1. Something basic about GIS
Ming-Chun Lee

2. What is GIS ? GIS = Geographic Information System Three components:
Geography – the real world
Information – data and information
Systems – technologies
So what is GIS?
we should first look at what the words themselves mean:
Geography: the real world, spatial realities, GIS is about representing, understanding, and analyzing our world,
Information: data and information, their meaning and use, GIS is about measuring the real world (data) and then gaining useful information from the measurements.
Systems: computer technology and its support infrastructure, GIS is a methodology, a system of techniques and principles, helping us deal with the data and derive the information

3. A Definition of GIS GIS = Geographic Information System Worboys, 1995:
A Geographic Information System (GIS) is a computer-based information system that enables one to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information.
GIS is a a computer-based technology and methodology for collecting, managing, analyzing, modeling, and presenting geographic data for a wide range of applications and uses.
What we mean by geographically referenced information:
Anything can be located on our world, physical objects, or a event,
and any description or accompanying information along with those things being described..

4. Functions of GIS Data Collection Storage & Management Retrieval
Conversion
Analysis
Display
Collection: from different data sources, allow different data formats
Storage & Management:
Retrieval: allow us to select data and view the data in a variety of ways, depending on what we want from the data, what kind of information we need
Conversion: change data format
Analysis: process data in order to gain useful information
Modeling: GIS allows us to understand how things work in the real world by only looking at the data. You have to be aware that data is only a small set of measurements about the reality, it is only a small window allows us to view the reality, we want to understand what is going on in the world, we have to look at the data, and base on the analysis of the data, we model the reality, and try to gain insight about our world.
Display: presenting data in different ways for easy understanding

5. Applications of GIS How GIS can be used: Infrastructure Management
Transportation Network Routing
Floodplain Management
Emergency Response Planning
Noise Pollution Analysis
Participatory Planning Processes
Jobs/Housing Spatial Balance
and more …
We have talked about what GIS means, what are GIS components, now let’s look at what GIS can do for us, or for the planners:
Infrastructure Management: like where need or can be put in a new wastewater treatment facility or plant, where we can put a new park
Transportation Network Routing: where a light rail or mono rail can go through, it would depend on where population are, where has high population density
Floodplain Management:
Emergency Response Planning: where are the current emergency response facilities, where we need to put in a new facility, how we can define emergency response districts based on the distribution of the emergency response facilities
Noise Pollution Analysis: based on available data, we can understand how bad the pollution or noise is,
Participatory Planning Processes: GIS capability to produce a variety of visual representations can really help laypeople the public to better understand what’s going on in their neighborhood, or in their city, help promote public participation
Jobs/Housing Spatial Balance: based on Census data, we can understand the distribution of income, housing, and some other social-economic characteristics about our city, so we can try to find what the problem could be and then try to find the treatment for it.

6. The GIS Data Model Data Organized by Layers/Themes Administrative
Digital Orthophoto
Streets
Hydrography
Parcels
Buildings
Zoning
Utilities
Administrative
Boundaries
As I pointed out before, data is the heart of GIS.
Now, let’s go understand how data is organized in GIS:
Data is Organized by different Layers/Themes, each layer or theme contains a certain type of data with a particular topic (or purpose). For example, (look at the graph)
Layers Integrated Using Explicit Location on the Earth’s Surface or say referencing to a certain geographic coordinate system, we will address the issue of coordinate system later in other lecture..
Data Organized by Layers/Themes

7. GIS Database GIS data is organized by Layers/Themes
A Theme is a collection of geographic features (usually a separate file), such as boundaries, roads, together with the attributes (may stored in other files) of those features
A set of Themes for a geographic area makes up a GIS Database (a group of files)

8. The GIS Data Model
Layers Integrate Using Explicit Location on the Earth’s Surface
Themes have to be georeferenced.

9. Georeferencing
Identifying Locations on the Earth Using Locations on a Map or GIS
Aspects of Georeferencing
Coordinate Systems
Geographic Coordinate System
Projected Coordinate System
Projections
Identifying Locations on the Earth Using Locations on a Map or GIS
You connect a location on a map to a location in the real world
Aspects of Georeferencing, what you need to do georeferecning:
Coordinate Systems
Geographic Coordinate System
Projected Coordinate System
Projections

10. Coordinate Systems A Method of Locating Objects on the Earth’s Surface
Examples:
Geographic (Global) Coordinate System
Projected (Cartesian) Coordinate System
A Method of Locating Objects on the Earth’s Surface
Examples:
Geographic (Global) Coordinate System
Projected (Cartesian) Coordinate System
Even though we said, projected CS, allow you to locate a feature on a map, but you still need to reference this point to a location in the real world, so your ultimate goal is still to Locating Objects on the Earth’s Surface

11. Geographic Coordinate System
Geographic Coordinate System (GCS) uses a three dimensional spherical surface to define locations on the earth.
Geographic Coordinate System (GCS) uses a three dimensional spherical surface to define locations on the earth.
A GCS includes an angular unit of measure, a prime meridian, equator, and a datum (based on a spheroid).

12. Geographic Coordinate System
In the spherical system, horizontal lines are lines of equal latitude, or parallels
Vertical lines are lines of equal longitude, or meridians.
These lines encompass the globe and form a gridded network called a graticule
In the spherical system, horizontal lines are lines of equal latitude, or parallels
Vertical lines are lines of equal longitude, or meridians.
These lines encompass the globe and form a gridded network called a graticule

13. Geographic Coordinate System
A point is referenced by its longitude and latitude values. Longitude and latitude are angles measured from the earth’s center to a point on the earth’s
surface. The angles often are measured in degrees (or in grads).
A point is referenced by its longitude and latitude values. Longitude and latitude are angles measured from the earth’s center to a point on the earth’s
surface. The angles often are measured in degrees (or in grads).

14. Measuring Latitude
North Pole (90 º N)
60 º N
Latitude Measures the Angular Distance from the Equator
60 º
Equator
South Pole (90 º S)
Side View

15. Measuring Longitude
135 º E
Longitude Measures the Angular Distance from the Prime Meridian (Greenwich, UK)
North Pole
Equator
135 º
70 º
70 º W
Prime Meridian (0 º)
Top View

16. Projected Coordinate Systems
A projected coordinate system is defined on a flat, two-dimensional surface.
A projected coordinate system is always based on a geographic coordinate system that is based on a sphere or spheroid.
In a projected coordinate system, locations are identified by x,y coordinates on a grid
A projected coordinate system is defined on a flat, two-dimensional surface.
A projected coordinate system is always based on a geographic coordinate system that is based on a sphere or spheroid.
In a projected coordinate system, locations are identified by x,y coordinates on a grid

17. Projection
Whether you treat the earth as a sphere or a spheroid, you must transform its three-dimensional surface to create a flat map sheet.
The Process of Systematically Transforming Positions on the Earth’s Spherical Surface to a Flat Map While Maintaining Spatial Relationships
Whether you treat the earth as a sphere or a spheroid, you must transform its three- dimensional surface to create a flat map sheet.
The Process of Systematically Transforming Positions on the Earth’s Spherical Surface to a Flat Map While Maintaining Spatial Relationships

18. Geometric Models for Projection
Conical
Tangent along a Specific Latitude
Screen is a conic surface. Lamp at the center of the earth
Cylindrical
Tangent along Equator or a Longitude
Screen is a cylindrical surface. Lamp at the center of the earth
Planar/Azimuthal/Zenithal
Tangent at a Single Point
Screen is a flat surface tangent to the earth. Lamp at various positions
Conical
Tangent along a Specific Latitude
Screen is a conic surface. Lamp at the center of the earth
Cylindrical
Tangent along Equator or a Longitude
Screen is a cylindrical surface. Lamp at the center of the earth
Planar/Azimuthal/Zenithal
Tangent at a Single Point
Screen is a flat surface tangent to the earth. Lamp at various positions

19. Map Projection and Distortion
For Geometric Properties Affected by Projection:
Shape or Angle
Area
Distance
Direction
All projections produce some distortion

20. Common Projection Systems
Universal Transverse Mercator (UTM)
State Plane (SP)

21. Universal Transverse Mercator
Series of Cylindrical Projections, Tangential to a Longitude Line
60 Zones, One Every 6 Degrees Longitude
Each Zone:
Width is 6º in Longitude
Height is from 80º S to 84º N in Latitude

22. State Plane Planar Projection Most States Have Two or More Zones
Tangent at Different Points for Each State
Most States Have Two or More Zones

23. Types of GIS Data Describes Objects In Terms Of: Spatial Data
Absolute X,Y Coordinates – Locations
Size, and Shape
Attributes
Characteristics associated with Geography
We can categorize GIS data into three different types:
First type is Spatial Data, include location, size, and shape,
Absolute X,Y Coordinates – Locations
Size, and Shape
For example, like land parcels, cone with locations, different sizes and shapes
Second one is non-spatial attributes:
Non-spatial Attributes
Characteristics Unrelated to Geography
For example, the owners’ names of those parcels, an owner can own multiple properties, the name is one of the attribute associate with parcels, but no really location specific
Topology
Spatial Relationships Between Features
How each feature relate with each other, like which one is connected to which one, which one is on the left of which one, those kinds of relations

24. GIS Associates Spatial and Attribute Data in a Geo-Referenced Database
ARC
INFO 1 3 5
ID AREA PERIM CLASS LANDUSE
Single Family
Multi Family
Commercial
Forest
Water 2 4
GIS Associates Spatial and Attribute Data in a Geo-Referenced Database

25. Data models
Data models: Formats in which geographic data is stored and managed.
Vector Data Models (Features)
Points
Lines
Polygons
Raster Data Models (Surfaces)

26. Raster and Vector Data Models
Raster Representation
Vector Representation
line
polygon
point
Let get started
Quick comparison between two different data models
Raster is represented by a grid of cells,
Vector is represented by point and line and polygon features
Point,

27. Raster Data Models Raster Data Model
Location is referenced by a grid cell in a rectangular array or matrix
Attribute is represented as a single value for that grid cell
Let’s take a closer look at the two data models:
First look at Raster:
the map on the bottom shows the reality
In raster data the entire area of the map is subdivided into a grid of tiny cells. A value is stored in each of these cells to represent the nature of whatever is present at the corresponding location on the ground.

28. Raster Data Models

29. Raster Data Models Raster Data Model Typical data sources:
Images from remote sensing (LANDSAT, SPOT)
Elevation data from USGS
Best for continuous data:
Elevation
Temperature

30. Raster Data Model Uses Elevation Temperature Noise Levels Air Quality
Distance or Accessibility Surfaces
Probabilities (e.g. flooding, liquefaction)
Photographic Images

31. Vector Data Models Vector Data Model
Location is referenced by x,y coordinates, which can be linked to form lines and polygons
Attributes referenced through unique ID number to tables
In vector data the features are recorded one by one, with shape being defined by the numerical values of the pairs of xy coordinates.
A point is defined by a single pair of coordinate values.
A line is defined by a sequence of coordinate pairs defining the points through which the line is drawn.
An area is defined in a similar way, only with the first and last points joined to make a complete enclosure.

32. Features
Geographic objects that have different shapes are represented as features
Geographic objects that have different shapes are represented as features

33. Features Points are a pair of x,y coordinates

34. Features Lines are sets of coordinates that define a shape

35. Features
Polygons are sets of coordinates defining boundaries that enclose areas.
Polygons are sets of coordinates defining boundaries that enclose areas.

36. Vector Data Models Vector Data Model Typical data sources:
DIME (Dual Independent Map Encoding) and TIGER (Topologically Integrated Geographic Encoding and Referencing file) files from US Census
DLG (Digital Line Graph) from USGS for streams, roads, etc.
Best for features with discrete boundaries:
Soil Type
Land Use
DIME file (Dual Independent Map Encoding)
introduced for the 1970 US Census and used again in 1980; replaced by TIGER in 1990
TIGER File (Topologically Integrated Geographic Encoding and Referencing file)
introduced for 1990 Census to eliminate inconsistencies between census products
USGS DLG (Digital Line Graph) file showing roads, streets, rivers,

37. Vector Data Model Uses Land Use or Zoning Classifications Polygons
Transportation Networks
Points and Polylines
Hydrology
Polylines for Rivers, Polygons for Water Bodies
Utilities
Points for Facilities, Polylines for Pipelines & Wires

38. Raster Advantages & Disadvantages
Easy to Understand the Data Model
Easy to Analyze
Low Computing Requirements
Compatible with Remote Sensing Sources
Efficient for Continuous Data
Easy to Use in Modeling
Raster Disadvantages
Spatial Inaccuracies Common
Low Resolution, Relative to Vector Data
Imprecise Locational Data
Requires All Cells to be Coded
Not As Efficient for Discrete Data or Features

39. Vector Advantages & Disadvantages
More Readable as a Map
Higher Resolution than Raster Data
Can Have High Spatial Accuracy
Can Have Storage Advantages
Can Be Topological
Efficient for Discrete Data or Features
Vector Disadvantages
Difficult to Manage Data Storage
High Computing Requirements
Complex to Perform Overlay and Modeling Operations
Inefficient for Continuous Data

40. Introduction to ArcGIS
ArcGIS is a software program , used to create, display and analyze geospatial data , developed by Environmental Systems Research Institute (ESRI) of Redlands, California.
OK, now we turn to our second topic:
Introduction to ArcGIS:
ArcGIS is a software program , used to create, display and analyze geospatial data , developed by Environmental Systems Research Institute (ESRI).

41. ESRI’s ArcGIS Platform
Suite of Three Integrated Applications:
ArcCatalog
ArcMap
ArcToolbox
As mentioned before, this class tries to make you all feel comfortable using GIS computer software. Speaking software, the package we are about to use is ArcGIS, and it is a whole package, come with a number of applications: the three most important applications are:
ArcCatalog
ArcMap
ArcToolbox
They support each other, we will have more about the package of software when we go through our first exercise, also on next lecture, I will be introducing me to some basic things about those three applications.

42. Components of ArcGIS
ArcCatalog is used for browsing for maps and spatial data and managing spatial data, viewing and creating metadata.
ArcMap is used for visualizing spatial data, performing spatial analysis and creating maps to show the results.
ArcToolbox is an interface for accessing the data conversion and analysis function that come with ArcGIS.
All three ArcGIS versions, come with three basic components:
ArcCatalog is used for browsing for maps and spatial data and managing spatial data, viewing and creating metadata.
ArcMap is used for visualizing spatial data, performing spatial analysis and creating maps to show the results.
ArcToolbox is an interface for accessing the data conversion and analysis function that come with ArcGIS.