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Peter Fox

GIS for Science

ERTH 4750 (98271)

Week 2b, Friday, February 3, 2012

GIS data. Preparing data for MapInfo. Making simple maps.

Layering. Querying and selecting data. Producing

thematic maps.

Logistics• 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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Contents• GIS data.

• Preparing data for MapInfo (geocoding, reformatting).

• Making simple maps.

• Layering.

• Querying and selecting data.

• Producing thematic maps.

• Next class(es)

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Reading• GPS

• Projections

• Reference systems

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GIS data• Spatial data - properties distributed over

geographical regions• Entities (geographical primitives, vector approach)

– Points – single point specified by coordinate pair (geodetic control points, fire hydrants, cities, observation point)

– Lines – single straight line specified by 2 endpoints (road segments, pipes)

– Polylines – line specified by multiple pairs if points, not closed loop (roads, powerlines, rivers, contours)

– Polygons – closed series of straight lines (political boundaries, house lots, parks, rivers, oceans, soil boundaries) 5

Example 1 - discuss

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Example of map comprising •raster base map, •point entities (survey marks), •polyline entities (roads), and •polygon entities (states).

Example 2

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Example 3

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Entities and Relationships*• Each of these entities can be given an array

of attributes (properties)

Examples: Density, soil type, number of occupants, income, speed limit

• Relationships among entities is called their topology (connectivity)

Examples: Distance to other entities, change in elevation, travel time between cities

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Huh, what about location?• Geographical location is specified by a

centroid (coordinates of the 'center of mass’)

• Centroids are important in spatial searches

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Continuous data?• Tesselation, rasterization

• Properties are assigned to a regular or irregular, smooth grid in geographical space (Topography, air pressure, water table)

• Regular grid points known as pixels (or voxels in 3D)

• Representation of the image with pixels is the raster data model

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Derived entities• New entities can be produced by union or

intersection of existing entities (road intersections as points)

• New attributes can be produced as logical or mathematical combinations of existing attributes; A’ = f (A1, A2, A3, …An)

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Preparing GIS data• Spatially enable data

– Where in geographical space is the entity– Geocoding - getting coordinates from another,

associated database, such as street addresses or zip codes

– Create points - coordinates already in database– Registration - where a raster image is located in

space

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Preparing GIS data (2)• Layering

– Information can be added/removed/edited/formatted in ‘layers’

– Order of plotting on maps can be changed– Layers can be merged/split/cross-referenced– 'Cosmetic' layer to add information on top of map

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Preparing GIS data (3)• Query and Select

– Select subsets of data based on specified conditions

– Conditions can be on attributes (e.g. states with population > 1 million) or spatial ( e.g. cities north of 45N)

– SQL (Structured Query Language)

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Preparing GIS data (4)• Thematic Mapping

– Map based on some theme, selection, relationship, etc.

– Vary map colors/grayscales according to selection or range of attributes

– Map attributes that are mathematical or logical combinations of other attributes

– Smooth data to create raster thematic map

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Preparing MapInfo data • MapInfo tables (.tab, .dat, .ind, .id, .map)• Workspace files (.wor)• ArcInfo files via Tools• Other input formats• Excel (.xls)• Delimited ASCII file (.txt)• dBase DBF (.dbf)• Microsoft Access (.mdb)• Lotus 1-2-3 (.wks)• Raster image files (.tif, .bmp, .jpg, .gif, …)• Grid image (.mig, .grd)

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MIF (Interchange Format)• MapInfo Data Interchange Format

(.mid, .mif files) see http://ees2.geo.rpi.edu/gis/mapinfo_mif.pdf

• The .mid and .mif files allow us to enter entity and attribute data into MapInfo via a text (ASCII) file. For full documentation click here. A printed copy is also on reserve in the Huntington Room.

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• The .mid file contains the attribute data (remember d for data) in a 2-dimensional list table. This file is optional.

• The number and types of attributes and number of entities must agree with the .mif file as described below.

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Example• This .mid file contains 3 attributes (columns)

and 4 entities (rows).

• The attributes here are the island name, the population, and the primary source of income.

http://escience.rpi.edu/gis/data/example.mid

Island A 20100 Coconuts

Island B 50000 Tourism

Island C 5000 Shoes

Road A 0 Driving

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More on mif• The .mif file contains the description of the

attribute types listed in the .mid file and the spatial data (coordinates) for the entities.

• The COLUMNS line tells how many columns there are in the .mid file.

• The next lines give the column header (description of attribute) and the data type (character, integer, floating point, etc.).

• The DATA section gives the types of entities and their coordinates.

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Read into MapInfo with Table > ImportVERSION 650

Charset "WindowsLatin1"

COLUMNS 3

Name char (15)

Pop_2000 integer

Income_source char (15)

DATA

REGION 1

5

150.15 5.18

150.18 5.21

150.24 5.41

150.11 5.32

150.12 5.25

REGION 1

3

147.97 4.49

148.12 4.22

148.19 4.47

REGION 1

4

149.4 4.49

149.32 5.61

149.0 5.58

149.22 5.32

PLINE

3

150.18 5.21

150.15 5.27

150.11 5.32 22

http://escience.rpi.edu/gis/data/example.mif

It should ~ look like:

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Details of some commands• POINT x y• LINE x1 y1 x2 y2• PLINE Numpts X1 y1 X2 y2 X3 y3 . . REGION n (n= # of

polygons) Numpts X1 y1 X2 y2 X3 y3

.

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Try some for yourself• Commands that is…

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Summary of commands• POINT – draws a point• LINE – draws a line• PLINE – draws a polyline• REGION – draws a region• ARC – draws an arc• CENTER - specify object’s centrid• TEXT – text string controls• RECT – rectangle• ROUNDRECT – rounded rectangle• ELLIPSE – ellipse• PEN – width, pattern, and color of pen strokes• BRUSH – pattern, foreground color, and background color of fill patterns• SYMBOL – shape, color, size, font, font-style, and rotation of symbols• FONT – font name, style, size, forecolor, backcolor

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More data to work with• http://escience.rpi.edu/gis/data/PRESSURE.

{mid,mif}

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Simple maps• Let’s load some maps into MapInfo

• http://escience.rpi.edu/gis/data/

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Layers• And now let’s put some layers on them

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Query• And query them…

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Selecting data• And select some data

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Thematic maps• A thematic map is a type of map or chart

especially designed to show a particular theme connected with a specific geographic area.

• These maps "can portray physical, social, political, cultural, economic, sociological, agricultural, or any other aspects of a city, state, region, nation , or continent”.

• (Wikipedia)

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Thematic Maps• And think about themes for a map

– Places to eat– Places of crime by type– Usual average temperature/ rainfall

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Summary• Preparing GIS data!

• Interacting with the data…

• What about themes?

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Reading for this week• None. Relax.

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Next classes• Week 3 - Buffering. Registering raster images.

Digitizing from the screen. Lecture Tue, hands on Fri.

• Ensure that you are getting a working knowledge of MapInfo / Map Basic

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