geospatial attribute data

1CS 128/ES 228 - Lecture 8b

Geospatial Attribute Data

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We Lied! Earlier this semester we claimed that data

was either spatial, i.e. said where something was, or attribute, i.e. told you something about an object.

In fact, on the exam, we accepted “non-spatial data” as part of the definition of attribute data.

BUT, it’s not that simple…

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Some attribute data is tied to a location, not an object

Estimate of phytoplankton distribution in the surface ocean: global composite image of surface chlorophyll a concentration (mg m-3) estimated from SeaWiFS data (Source: NASA Goddard Space Flight

Center, Maryland, USA and ORBIMAGE, Virginia, USA).

Estimate of phytoplankton distribution in the surface ocean: global composite image of surface chlorophyll a concentration (mg m-3) estimated from SeaWiFS data (Source: NASA Goddard Space Flight

Center, Maryland, USA and ORBIMAGE, Virginia, USA).

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Spatial Data – A Few Definitions Spatial data: Data that have some form of spatial or

geographical reference that enables them to be located in two or three-dimensional space. -- Heywood, Cornelius & Carver, p. 289

Spatial data: Data that relate to the geometry of spatial features. -- Chang, Introduction to Geographical Information Systems, p. 4

Spatial data: Any information about the location and shape of, and relationships among, geographic features. This includes remotely sensed data as well as map data. -- The GIS Dictionary, http://www.geo.ed.ac.uk/agidict/welcome.html, searched 3/27/2007 (as of 11/11/2008, “temporarily unavailable”)

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A Compromise

Geospatial Attribute Data

Data about a non-spatial entity that is intrinsically tied to a given

location

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Examples of Geospatial Attribute Data• Rainfall • Snow depth• Land use• Crime rates• Average income level• Population statistics

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What is special about this data?

Data sets are generally very large

Turning such data into information (or knowledge) can be tricky (or worse!)

Dimensionality becomes an issue

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Dimensionality Paper maps are

generally two-dimensional

While color can be used as a third dimension, it is more often used for attribute display

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Sometimes 2-D works

Source: U.S. Census Bureau, 2005 American Community Survey (American FactFinder)

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More fine-grained 2-D

Image from: http://www.csc.noaa.gov/products/nchaz/htm/lidtut.htm

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What’s the Weather Like in Merry Old England? Source

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When 2-D tends to work

“Planar” area being mapped

One piece of data for each position

Minimal problem locating data in “space”

No “time” dimension

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What about Time?

Traditionally described as a “fourth” dimension, time adds a “third” dimension to GIS data.

This creates problems converting the data to information and knowledge.

2-D maps usually don’t cut it.

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Solutions to the “Time Dilemma”:1. Graphs

Source: National Weather Servicehttp://newweb.erh.noaa.gov/ahps2/hydrograph.php?wfo=buf&gage=olnn6&view=1,1,1,1,1,1

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More graphing

http://www.pmel.noaa.gov/tao/disdel/disdel.html

Tropical Ocean Array

• Buoys in Pacific Ocean• Monitor Conditions• Monitor El Niňo

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Custom Graphs from TOA Monthly Wind

Speed data for the buoy I selected

1977-2007

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Also available as… Downloadable data file

Formatting can be an issue But if you add it to your GIS, it’s yours!

Location: 8S 165E 16 Aug 1991 to 16 Mar 2007 ( 188 times, 2 blocks) Gen. Date Mar 28 2007 Units: Winds (M/S), W. Dir (DEG), -99.9 = missing, (1,1) is NE at sqrt(2) m/s Time: 1200 16 Aug 1991 to 1200 16 Aug 1996 (index 1 to 61, 61 times) Depth (M): -4 -4 -4 -4 QUALITY YYYYMMDD HHMM UWND VWND WSPD WDIR SD 19910816 1200 -5.0 0.7 5.6 278.1 22 19910916 1200 -2.9 -1.4 4.8 243.7 22 19911016 1200 -2.7 -0.1 3.4 268.2 22 19911116 1200 -0.2 2.1 4.3 354.3 22 19911216 1200 -0.5 1.7 3.3 344.0 22 19920116 1200 1.8 1.3 4.2 53.8 22 19920215 1200 4.4 0.3 5.3 86.2 22 19920316 1200 4.0 1.0 5.3 75.7 22

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Solutions to the “Time Dilemma”:2. Multiple Images Really just a set of 2-D images shown side-by-

side or in sequence

Source:http://commons.wikimedia.org/wiki/Image:ElectoralCollegeYYYY-Large.png

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Items of note • Each of the images here is a separate report (or is it “map”?), no longer directly connected to a GIS

• Each map actually contains summary information as well as traditional map elements

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Solutions to the “Time Dilemma”:3. Animation

http://encarta.msn.com/encyclopedia_761567360_1/Animation.html

Animation: motion pictures created by recording a series of still images—drawings, objects, or people in various positions of incremental movement—that when played back no longer appear individually as static images but combine to produce the illusion of unbroken motion.

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My Daily Habit – Doppler DataAnimation

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More Weather From England

http://www.xcweather.co.uk/

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Watch My Friends Ride Across The Country http://stats.raceacrossamerica.org/2006/animation/

A similar site, with elevation profiles, exists for the Tour de France, but it only animates during the race

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Get Seasick?

http://www.pmel.noaa.gov/tao/jsdisplay/

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What if there is a real third dimension?

Actual images (video) But these can only show “transparent” or

“discrete” attribute data Flyovers/fly-throughs help

Virtual reality But most users don’t have the equipment

to “view” this

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And in the movies…

(Screen snapshot of) Animation of tornado-monitoring “buoys” from the Warner Brothers film Twister

Source: http://www.vfxhq.com/1996/twister.html

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Conclusions about geospatial data

• It’s abundant• It’s important• Display is a challenge• Technologies only get better

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Great Data Sets Abound

• Census bureau• USGS• Weather Service• Scientific labs

(esp. government funded)