Introduction to Geographic
Information Systems for
Science
Peter Fox
GIS for Science
ERTH 4750 (98271)
Week 2, Tuesday, January 31, 2012
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Contents
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Introductions
Course Outline
Application areas
Logistics and resources
Assessment and assignments
Learning objectives, outcomes
Introduction to GIS for Science
Next class(es)
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Introductions
• Name, major, year
• Interests, goals, outcomes
• Have you completed any *suggested*
prerequisites:
– Geography, cartography.
– Other spatial analysis.
– Mathematics background
• Questions
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Course Outline (tentative)
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Week 2 (Jan. 31/Feb 3): Topic 1/2. Introduction to GIS. Map projections and reference
systems. Introduction to MapInfo Professional software. GIS data. Preparing data for
MapInfo (geocoding, reformatting). Making simple maps. Layering. Querying and selecting
data. Producing thematic maps.
Week 3 (Feb. 7/10): Topic 3. Buffering. Registering raster images. Digitizing from screen.
Week 4 (Feb. 14/17): Topic 4. Geocoding with streets/addresses. Simple interpolation
(IDW).
Week 5 (Feb 21/24): Topic 5. Introduction to geostatistics. Interpolation techniques
continued (trend surfaces, Thiesses polygons, inverse distance weighting, splines)
Week 6 (Feb. 28/31): Topic 6. Interpolation continued (variograms, kriging)
Week 7 (Mar. 6/9): Topic 7. Analysis of continuous surfaces (filtering, slopes, shading)
Mar. 13/15: no classes - spring break
Week 8 (Mar. 20/23): Topic 8. Analysis of errors
Week 9 (Mar. 27/30): Topic 9. Analysis of discrete entities
Week 10 (Apr. 3/6): Topic 10. Graphs, grouping, pie charts
Week 11 (Apr. 10/13): Topic 11. Editing attributes, manipulating objects in MapInfo
Week 12 (Apr. 17: no class) - Grand Marshall week (Apr. 30) Topic 12. Making a map from
scratch, field observations
Week 13 (Apr. 24/27): Prepare for class presentations
Week 14 (May 1/4): Topic 13. Class project presentations
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Logistics
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Class: ERTH 4750
Hours: 12pm-1:50pm Tuesday, Friday
Location: SAGE 2704
Instructor: Peter Fox - pfox@cs.rpi.edu or
foxp@rpi.edu , x4862
Contact hours: Tuesdays 2pm-3pm (or by appt)
Contact location: JRSC 1W06 or Winslow 2120
TA: Max Cane, canem@rpi.edu
Web: http://tw.rpi.edu/web/Courses/GIScience/2012
– Schedule, syllabus, reading, assignments, etc.
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Assessment and Assignments
• Via written assignments with specific percentage of
grade allocation provided with each assignment
• Via individual oral presentations with specific
percentage of grade allocation provided
• Via group presentations – depending on class size
• Via participation in class (not to exceed 10% of
total) – this works by ‘losing’ points by not
participating
• Late submission policy: first time with valid reason –
no penalty, otherwise 20% of score deducted each
late day
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Assessment and Assignments
• Reading assignments
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Are given almost every week
Most are background and informational
Some are key to completing assignments
Some are relevant to the current week’s class (i.e. follow
up reading)
– Others are relevant to following week’s class (i.e. prereading)
– Undergraduates - will not be evaluated on but we will
often discuss these in class and participation in these is
taken into account
– Graduates – are likely to be tested as part of
assignments, i.e. an extra question
• You will progress from individual work to group work
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Goals
• To provide students an opportunity to learn
geospatial applications and tools.
• To introduce relational analysis and interpretation of
spatial data and presentation on maps.
• Introduce spatial database concepts and technical
aspects of query languages and geographic
integration of graphic and tabular data.
• To introduce intermediate aspects of geospatial
analysis: map projections, reference frames,
multivariate analysis, correlation analysis,
regression, interpolation, extrapolation, and kriging.
• To gain experience in an end-to-end GIS
application via a term project.
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Learning Objectives
• Through class lectures, practical sessions, written
and oral presentation assignments and projects,
students should:
– Demonstrate proficiency in using geospatial applications
and tools (commercial and open-source).
– Present verbally relational analysis and interpretation of a
variety of spatial data on maps.
– Demonstrate skill in applying database concepts to build
and manipulate a spatial database, SQL, spatial queries,
and integration of graphic and tabular data.
– Demonstrate intermediate knowledge of geospatial
analysis methods and their applications.
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Academic Integrity
• Student-teacher relationships are built on trust. For example, students
must trust that teachers have made appropriate decisions about the
structure and content of the courses they teach, and teachers must trust
that the assignments that students turn in are their own. Acts, which
violate this trust, undermine the educational process. The Rensselaer
Handbook of Student Rights and Responsibilities defines various forms
of Academic Dishonesty and you should make yourself familiar with
these. In this class, all assignments that are turned in for a grade must
represent the student’s own work. In cases where help was received, or
teamwork was allowed, a notation on the assignment should indicate
your collaboration. Submission of any assignment that is in violation of
this policy will result in a penalty. If found in violation of the academic
dishonesty policy, students may be subject to two types of penalties. The
instructor administers an academic (grade) penalty, and the student may
also enter the Institute judicial process and be subject to such additional
sanctions as: warning, probation, suspension, expulsion, and alternative
actions as defined in the current Handbook of Student Rights and
Responsibilities. If you have any question concerning this policy before
submitting an assignment, please ask for clarification.
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Questions so far?
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Skills needed
• Geography?
– Nah, we’ll cover that
• Literacy with computers that can load/ run the
relevant applications
– Yep
• Ability to access internet and retrieve/ acquire
data
– Oh yea
• Presentation of assignments
– Ditto
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What is expected
• Attend class, complete assignments (esp.
reading)
• Participate
• Ask questions
• Work both individually and in a group
• Work constructively in group and class
sessions
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Also on the web
• Reading assignments – are intended to
prepare you for following lectures and may be
considered materials for written assignments
or project
• Assignments will be posted there
– Individual
– Group
• Max is your first contact for assignment
questions
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This course
• GIS – in short: computer-based mapping,
analysis and retrieve of location-based data
• (in) Science, i.e. the process part – but since
not all of you are in science, think of it as your
application area
• Relation to GPS, Remote Sensing
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GIS in Science (e.g.)
• Think about a place (location or feature) or a
topic
• Form your question (Data Science: Goal)
• Find/access/analyze data (most often onto a
map
• Explore the patterns and related information
presented
• Enhance the data, add more data or try an
alternate analysis
• Same question or a new one?
• 'Repeat'
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Introduction to GIS
• The importance of information for GIS:
information is the heart of GIS.
• GIS data: spatial data (mappable data)--referring to space, occupying space, and
having cartographic space; non-spatial data -- attribute data
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Data-Information-Knowledge
Ecosystem
Experience
Data
Creation
Gathering
Information
Presentation
Organization
Knowledge
Integration
Conversation
Context
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As a consequence …
• We’ll need to explore some ‘information’
concepts along the way in this course
• If you ever want more… try Xinformatics
(offered in the spring, 4xxx/6xxx)
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Introduction to GIS
• GIS infrastructure: hardware, software, data,
organization, and people.
• GIS generic questions: location, areal
relationship (measurement and neighborhood
analysis), attributes, patterns, relationships,
and trends.
• Exercise:
http://www.corvallismaps.com/multimap/
Select 18TH and St. and Search, select ‘707’ 20
and look at the returned screen
Introduction to GIS
• GIS and GPS (see reading also)
• Relationships among objects on maps
(‘computerized cartography’ plus a lot more)
• Purpose of GIS – regroup attributes, perform
calculations with built-in functions, edit data,
get new data, parse data, select, query,…
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GIS Objects
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Practical example
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Point: Single coordinate pair (Fire hydrant)
Line: 2 coordinate pairs (Road segment)
Polyline: > 2 points, open figure (Highway)
Region: polygons (State, county)
Groups of regions/points/lines
• GIS is the process of dealing with the
geographical relationships among these
objects
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Questions for a GIS
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What exists at a certain location?
Where are certain conditions satisfied?
What has changed in a place over time?
What spatial patterns exist?
What if this condition occurred at this place?
(modelling, hypothesis testing)
• (from Dawn Wright, OSU/GIS465)
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Where is this?
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So what’s this?
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Map projections
• Representation of the surface of a 3D
spherical or ellipsoidal body on a 2D planar
map
• Who has used
– Google Earth?
– Microsoft Visual Earth?
– NASA WorldWind?
– Another?
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Yes
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3D worlds
• Great circle - path of minimum distance on surface
of sphere, intersection of sphere with plane passing
through center of sphere, radius is that of sphere
• Small circle - intersection of any plane with surface
of sphere, has radius equal to or less than radius of
sphere
• Map projections (reading):
– Always have distortions
– User chooses which characteristics to
be correct
– Distortions depend on scale
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Properties** to conserve
• Area – coin covers the same area anywhere
on map (equal area, equivalent,
homolographic, authalic, equiareal)
• Shape – relative local angles are correct
(conformal, orthomorphic)
• Scale – no projection conserves scale
throughout, equidistant projections give true
distances from one point to all others
• Direction – azimuthal projection conserves
direction from center of map to all other
points
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Projections
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Other projections
• Mercator – lines of constant direction are
straight
• Gnomonic – great circles are straight lines
• Stereographic – great/small circles are circles
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Types of projections
• Cylindrical, conical, planar – can be transformed
(unwrapped) to plane without distortion
– Conical – meridians radiate from point, parallels are
circles
– Cylindrical – meridians, parallels are straight lines (eg
Mercator)
– Planar – meridians radiate from point as straight lines,
parallels are circles
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Types of projections
• Parallels – lines of equal latitude; intersection of
Earth’s surface with planes that parallel the equator;
form small circles
• Meridians – lines of equal longitude; planes
intersect N and S poles, perpendicular to equator,
these are great circles at equally spaced angles,
that get close together as one approaches poles
• Oblique projections – cylinder that is not parallel to
earth’s axis, cone does not intersect earth’s axis,
plane not perpendicular to earth’s axis, results in
distortions of parallels and meridians
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Distances on the Earth
• At equator only, 1° latitude = 1° longitude.
• For sphere (or circle) the total circumference
= 2 pi R (pi = 3.1415926…, R = radius)
For arc of angle a the arc
length is aR.
(a is always in radians,
for sphere a = 2 pi )
R for Earth = 6370 km so
a = 1° = 111.19 km.
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References for Coordinates
• Equator – latitude = 0, positive northward,
negative southward
• Prime meridian (Greenwich UK) longitude =
0, positive eastward, negative westward
• Grids, often made of lon-lat
• Cartesian coordinate systems, usually local,
designate points by perpendicular distances
from axes on a flat map
• Y – meridians, positive North (northings)
• X – parallels, positive East (eastings)
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United States
• In US we use UTM (Universal Transverse
Mercator) and SPCS (State Plane Coordinate
Systems)
Large regions are divided into zones to decrease distortion.
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Oblate spheroid
Earth is flattened by about f » 1/300
f = (a-b)/a » 1/300 » 22 / 6370 km; a – b » 22 km
Earth’s flattening is sufficient to distort maps at
1:100,000 and larger scales.
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In reality – it’s a Geoid
• Earth is not an exact ellipsoid and its real shape is
called the geoid. The geoid is the shape the Earth’s
surface would have if it was entirely covered with
water, in other words, sea level defines the geoid
and is an equipotential surface. Local variations in
the gravity field cause the geoid to stray from the
ellipsoid by ~ ± 100 meters in height.
• The geoid is important in surveying because it
locally defines vertical (by gravity). Elevations
estimated by traditional leveling are relative to the
geoid and not to the ellipsoid. Elevations estimated
by GPS are relative to the ellipsoid.
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Reference ellipsoid
• Reference ellipsoid requires 2 constants be
specified; (1) a and b, (2) a and f, or (3) a and e (e =
eccentricity).
• There are many different global datums in use
today. Satellite-based reference systems e.g.
GRS80 and they largely differ in shape of Earth
used.
• NB. a datum is a reference point or surface against
which position measurements are made, and an
associated model
• Global a and f may be inaccurate for local or even
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continental scale surveying. Local values used to
increase local accuracy.
Reference ellipsoid
• NAD83 (and 27, the North America Datum)
terrestrial and space-based WGS84 (and 72, 64
and 60 of the World Geodetic System) is being
replaced by GPS-based reference system
• Perhaps even a ‘moving’ reference frame like
ITRF96 (International Terrestrial Reference Frame)
in which points are given initial positions and
velocities
• OSGB36 of the Ordnance Survey of Great Britain
• ED50, the European Datum
• Australians, everyone…
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Latitude for an ellipsoid
• A = geographic (geodetic) latitude,
• B = geocentric latitude
• A is slightly greater than B, at poles and
(recall) equator A = B
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Huh? Geodetic/geocentric?
• It is important to note that geodetic latitude is
different from geocentric latitude.
• Geodetic latitude is determined by the angle
between the normal of the spheroid and the
plane of the equator, whereas geocentric
latitude is determined around the center
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Summary
• GIS relies on basic elements (review)
• Information and Science
• Having seen this simple introduction be
thinking of how to use GIS for Science, i.e.
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What exists at a certain location?
Where are certain conditions satisfied?
What has changed in a place over time?
What spatial patterns exist?
What if this condition occurred at this place? (modelling, hypothesis
testing)
– (from Dawn Wright, OSU/GIS465)
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Reading for this week
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GPS
Map projections
Georeference systems
MapInfo User Guide and other docs
• We will discuss (and install, work with) these
on Friday (3rd)
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Next classes
• Fri class was to be install MapInfo / Map Basic
• Start working with it, ask questions…
• In preparation – see the notes that Max put together
(under reading)
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