UP Geographic Information System Discussion Questions

1) What is the difference between GIS and CAD? Why GIS and CAD both exist?

2) Imagine you are looking at a geodatabase that contains 50 states, 500 cities, and 100 rivers. How many feature classes are there? How many features? How many attribute tables? How many total records in all the attribute tables?

References

Kang-Tsung Chang (2016) Introduction to Geographic Information Systems, 9th edition, NY: McGraw-Hill ISBN19: 978-1-259-92964-9

Additional Reading Materials:

Wilpen Gorr, Kristen Kurland (2017) GIS Tutorial 1 for ArcGIS PRO, ESRI Press,

Michael Law, Amy Collins (2018) Getting to Know ArcGIS Desktop, 5th edition for ArcGIS 10.6, ESRI Press

GIS 580:
GeoSpatial Intelligence
LECTURE 2:
What and Why GIS
and Geospatial Intelligence?
Professor, Dr. Sergei Andronikov
Spatial Awareness
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Lecture outline:
Taxonomy of Information Systems
Where to begin?
Graphic & Numerical Environment
Special about Spatial
Spatial Elements
Spatial Measurement Levels
Spatial Location
Spatial Patterns
Spatial Dependancy
GIS Layers
A Taxonomy of Information Systems
Information
Spatial
Nonspatial
Non-geographic
Management
systems
(not generally geocoded)
Other GIS
AutoCAD
Market analysis
Geographic Info
System (GIS)
LIS
Socioeconomic
Non-parcel based
Census, political,
transportation
Parcel based
(cadastre, owner)
Where to BEGIN…..
• GIS software is not like the PC MSWord
• GIS assumes you are familiar with the
vocabluary of maps
• THINK ABOUT:
• representing spherical surface onto a flat piece
of paper;
• generalization and map scale;
• that a map is a MODEL of reality. Limitations;
• identification problems;
• classification problems.
Nature of Geographic Data
• In GIS we travel the environments that are GRAPHIC
and NUMERICAL representation of the real world.
• The nature of the data often dictates not only HOW we
will represent the earth inside a GIS database, but
HOW EFFECTIVELY we will analyze and interpret the
results of the analysis
• The points, lines, and areas are all different.
• We must consider : temporal scale; physical size of
objects stored in GIS database; the measurement level.
• You have to think SPATIALLY.
Special thoughts about
Spatial Data
• “STOP AND SMELL ROSES…”
Nature of Geographic Data
• Notice the spatial arrangements of plants & animals;
Notice the difference in your own path as you travel up & down the hill
• Recognize the patterns of agriculture;
• Take note of water, air pollution;
• Become aware of the differences in urban and suburban neighborhoods;
• BECOME MORE SENSITIVE TO THE OBJECTS !!!
Spatial Geographic Data
• THE FOCUS OF GEOGRAPHY & GIS • The SEARCH for SPATIAL ORDER
Spatial Geographic Data
San Francisco Bay. Landsat Image.
Better at interpreting space in general and at using GIS in particular
Spatial Elements
• SPATIAL, real-world, objects inside the
GIS will be represented by THREE types:
• a. Points;
• b. Lines;
• c. Areas.
Spatial Elements
• POINT FEATURES
• Trees, houses, road intersections….
• Spatial phenomena that occurs at ONLY ONE
location in space.
• Each feature is DISCRETE. It can occupy ONLY
a given point in space at any time.
• Have NO spatial dimension (length/width).
• Can be referenced by its location coordinates.
Spatial Elements
• LINEAR (LINE) OBJECTS
• Roads, rivers, regional boundaries, fences,….
• Occupy ONLY a SINGLE dimension in coordinate
space.
• You can measure the spatial extent, shapes, and
orientation of linear objects.
• No width. Skinny.
• Can be thought of as explicitly spatial because
separates two portions of geographic space.
Spatial Elements
• AREAS
• A continent, a city, a yard,….
• Occupy BOTH length and width.
• You can describe their shapes, orientation, and
AMOUNT OF TERRITORY they occupy.
• A 3-dimensional object. Adding the dimension of
height.
• Hills, valleys, ridges, cliffs, …….
• Surface features are CONTINUOUS .
• The possible values are distributed without
interruption continuously across the surface.
Building complex features
• Simple geographic features can be used to
build more complex ones.
• Areas are made up of lines which are made
up of points represented by their
coordinates.
• Areas = {Lines} = {Points}
Areas are lines are points are
coordinates…
Properties of Spatial Entities
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ENTITY – the spatial object (feature).
PROPERTIES:
Size
Distribution
Pattern
Contiguity
Neighborhood
Shape
Scale
Orientation.
Basic
properties
of
geographic
features
Spatial Measurement Levels
• The additional non-spatial information associated with a
geographic entity is the entity’s ATTRIBUTE.
• Different levels of measurement the attributes.
• 1 level. The Nominal Scale. Named data (a maple, an oak)
• 2 level. An Ordinal Scale. Ranked on the basis of
quantitative measure.
• 3 level. The Interval Level. Info is arranged using a
standard scale (temperature,…).
• 4 level. Ratio (elevation above sea level, precipitation,
population, ….).
Spatial Measurement Levels
• Nominal
Points
Lines
Areas
Ordinal
Ratio
A Fundamental Model of
Geographic Data
• The fundamental language of Geography is
THE MAP.
• It is a graphic abstraction of reality, a
MODEL of spatial phenomena.
• NOT a miniature version of reality.
• Understanding the way maps are encoded to
be used in GIS requires knowledge of
cartography.
A Fundamental Model of
Geographic Data
A Fundamental Model of
Geographic Data
• The MAP is composed of:
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different GRID systems;
projections;
symbol libraries;
methods of generalization;
scales.
Models of the Earth
• The earth can be modeled as a
– sphere,
– an oblate ellipsoid, or a
– geoid.
THE SHAPE OF THE EARTH
SPHERE
ELLIPSOID (SPHEROID)
THE SHAPE OF THE EARTH
DISTANCES:
• around the Earth pole to pole = 39,939,593.9 meters;
• around the equator = 40, 075,452.7 meters.
• a flattering of the ellipsoid = 1/298.257
Earth Models and Datums
Height
Terrain
Geoid
Sea Level
Ellipsoid
Sphere
Figure 2.4 Elevations defined with reference to a sphere, ellipsoid, geoid, or local sea level will all
be different. Even location as latitude and longitude will vary somewhat. When linking field data
such as GPS with a GIS, the user must know what base to use.
The Datum
• An ellipsoid gives the base elevation for
mapping, called a datum.
• Examples are NAD27 and NAD83.
• The geoid is a figure that adjusts the best
ellipsoid and the variation of gravity locally.
• It is the most accurate, and is used more in
geodesy than GIS and cartography.
TYPES OF PROJECTIONS

• Projections
TYPES OF PROJECTIONS
• Projections
MAP PROJECTIONS
• PROJECTION designates the method of representing a curved surface
on a flat map.
• MAIN MAP PROPERTIES & PROJECTIONS:
1. AREA:
• Equal-area or equivalent projections
2. SHAPE:
• Conformal projections.
• A map can not be both equivalent and conformal !
3. DISTANCE:
• Equiditsant projections
A map can not be both equivalent and equidistant !
4. DIRECTION
• Azimuthal projections
An azimuthal projection may also be equivalent, conformal or equidistant
TYPES OF PROJECTIONS
• Projections
TYPES OF PROJECTIONS
• Projections
TYPES OF PROJECTIONS
• Goode’s Homolosine.
• A combination of 2 projections: equal-area and shapes.
TYPES OF PROJECTIONS
• Projections
Coordinates
• The Cartographic System
for
the
Earth
90N
– Lines of Latitude (running east-west; app.Meridian
69 miles)
(Line of Longitude)
– Lines of Longitude (running north-south)
0
Equator
Parellel
(Line of Latitude)
Prime Meridian
90S
Mercator Projections
Atlas GIS
The Information Mapping System for Windows
Miles
0
2000
4000
Robinson
Atlas GIS
The Information Mapping System for Windows
Miles
0
2000
4000
Scale
• Scale is the ratio of the distances of objects
represented on the map to the actual distances of
these objects on the earth’s surface
• 1:1.000.000
Map Scale
• Map scale is based on the representative fraction (RF), the
ratio of a distance on the map to the same distance on the
ground.
• Most maps in GIS fall between 1:1 million and 1:1000.
• A GIS is scaleless because maps can be enlarged and
reduced and plotted at many scales other than that of the
original data.
• To compare or edge-match maps in a GIS, both maps
MUST be at the same scale and have the same extent.
• The metric system is far easier to use for GIS work.
Small scale
• Smaller scale maps represent the map
objects with a larger ratio (1:1,250,000)
Large Scale
• Large scale maps represent the map objects
with a smaller ratio (e.g., 1:10,000)
LMI GIS Training
Economic Data for North Carolina
Summer, 1995
D
Miles
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