Supporting Resources

for Lecture 03: Components of GI and Reference Systems

Index of Resources:

• Citations to literature
• Components of GI
• Reference Systems
  • Time
  • Space
  • Attribute

Citations to literature implied in lecture

The division of maps into general and thematic dates back to the first half of twentieth century.

• Raisz, E. 1948: General Cartography. New York: McGraw­Hill.
• Raisz, E. 1962: Principles of Cartography. New York: John Wiley.

The division continues in the basic texts on cartography (such as:)

• Robinson, A. H. 1953: Elements of Cartography. New York: John Wiley, first edition.
• Robinson, A. H., Morrison, J. L., Muehrcke, P. C., Guptill, S. C. and Kimerling, J. 1995: Elements of Cartography. New York: John Wiley, sixth edition.
• Dent, Borden, Thematic Cartography (three editions...)

John K. Wright (originator of "dasymetric" mapping) had a much more creative view than the rest of the folks at the time...

• Wright, J. K. 1936: A method of mapping densities of population with Cape Cod as an example. Geographical Review 26: 103-110.
• Wright, J. K. 1955: "Crossbreeding" geographical quantities. Geographical Review 45: 52-65.

Recognition of Fixed, Controlled and Measured, David Sinton:

• Sinton, D. F. 1978: The inherent structure of information as a constraint to analysis: Mapped thematic data as a case study. In Harvard Papers on Geographic Information Systems, 6 , ed. G. Dutton, p. 1-17. Reading MA: Addison Wesley.

Treating Time and Space together:

• Hägerstrand, Torsten 1970: What about people in regional science? Papers of the Regional Science Association 14(7): 7-21.
  

Components of Geographic Information

Time, Space and Attribute:

fairly common division in geography; lots of controversy about "absolute" versus "relative" spaces

Space-time diagrams have remained a textbook exercise, largely. One artist has created a neat set that represent her week in Minneapolis.

Divisions between time, space and attribute are practically more complicated: attributes are often about time, clocks are used to measure space (astronomically); we use time to describe distance (assuming that everyone has a motor vehicle)...

Resources on Reference Systems

Reminder: A reference system incorporates a package of decisions about measurement of some property; it provides a means to compare things (at the simplest level).

Temporal Reference Systems

• Clocks
  The number system: Egyptian? Babylonian? heritage (base 12 and base 60) hours, minutes, seconds [a very old technology, linked to astronomy]
  Technology of time-keeping:

  Books:

  Crosby on time in middle ages

  Latitude by Sobel: chronometer in 18th century
  Network Time Protocol clocks (mean versus siderial times relate to astronomical basis of observations):

  Universal Time from US Naval Observatory

  right now at UW
  Distinction between "mean" time and siderial time, a calculator, to confuse you completely) One explanation of the differences between them. Another description of the Equation of Time (relation of solar time to mean time)
• Calendars (see a more exhaustive description of types)
  Solar (eg. Gregorian 365 days, leap year rules, etc. )

  Roman origins: base dates: "ab urbs condita" (founding of Rome); 1 AD = 754 AUC (set by Dionysius Exiguus in 547 AD)

  Julian calendar (Julius Caesar) had basic leap years every 4

  Gregorian (Pope Gregory) refined leap years 97 in 400 years; originated in 1582

  required dropping 10 days, so 15 October followed 4 October.

  BUT not adopted uniformly - Geography of calendar conversion

  Countries converting later had to drop more days

  (eg. "November Revolution" in 1918 Russia)

  Then the age-old problem of formatting dates

  "American" mm/dd/yy

  "European" dd/mm/yy

  "international" ISO 8601 CCYY-mm-dd
  Revolutionary France started a new origin (Year 1 retroactively the adoption of the Convention in 1792), uniform 40 day months, 10 day "weeks"... Napoleon reinstituted the conventional calendar after a few years (1806). Another resource on the revolutionary calendar.
  And when did the Millenium start?

  The Greenwich case...
  Lunar

  Islamic calendar is purely lunar 12 months (moon cycles) of 29.53 days = 354.36 days per year. Year 1: Flight of Mohammed to Medina (Hijra), 1 AH (622 AD). 2000 (gregorian) was AH 1421 (though 622 is only 1378 solar years); the year is of different length...

  or a lunar calendar with 17 months and leap year every 50 years...
  mixture of lunar and solar

  Hebrew calendar (with leap months)

  Israel officially uses the religious calendar, but operates on Gregorian.

  Chinese calendar (predates the Romans)
  Scientific calendars

  Gregorian calendar basically counts DAYS, based on "universal day" (Julian)

  So did the Mayans' Long Count

  Geological dating (BP: Before Present): 1950 established as "Present"

  Groups advocating calendar reform.

Spatial Reference Systems

• "Geographic" Latititude-Longitude
  • Based in Equator (astronomical), axis of rotation (at right angles to Equator) plus an arbitrary Zero for Longitude (Greenwich Meridian) [based on astronomical observations at Royal Observatory in Greenwich]. Due to astronomical origins, time and longitude are defined basically on a common reference system.
  • (NOT absolute, but relative to a Datum, an earth model and positions for other places); a NIMA description of precise positioning;
  • Thus, Greenwich is no longer actually at 0! Datums matter...

A spatial reference system includes:

These decisions are often packaged up into a conventional coordinate system (spatial reference system) such as UTM or State Plane (in the USA) [Including the Washington Coordinate System established by state statute], or various national grids elsewhere (UK National Grid, France Grille Lambert, Germany Gauss-Krueger, Finland etc.). Many maps (such as USGS topographic quadrangles SHOW multiple coordinate reference systems: they are only constructed in one of these...). Australia has a number of spatial reference systems AND some neat tools to convert between them

A full coverage of issues of geodetic datums {Geographer's Craft Project]; Geodesy for the Layman (NIMA) other NIMA Geodesy publications; the current accepted world standard WGS 84

Resolution of coordinates not entirely identical to scale (in traditional sense) - but this is an issue of representation (covered in Chapter 3)

This topic becomes a much more central component of Geography 465 (winter 2005)

Attribute Reference Systems:

Systeme Internationale d'Unitiés (SI):

codified by international agreement in 1875. Colloquially referred to as the "metric system" in the USA (it is actually official, despite our day-to-day lack of metric units).

Defines seven base units:

meter	length
kilogram	mass
second	time
kelvin	temperature
ampere	electrical current
mole	chemical quantity
candela	intensity of light

More on SI, base units, conversion between units, etc.

Using these base units, many physical quantities are expressed in "derived" scales explicitly (as in meters per second (velocity), meters per second squared (acceleration), or in units like feet, hours, hectares, acres, watts, newtons or joules that are defined by some formula based on the base units.

US Office of Weights and Measures (National Institutes of Standards and Technology (NIST) was called Bureau of Weights and Measures)

Historical note

Civilization (meaning organized human activity including as commerce, science, political authority) has depended on sharing systems of measurement. Standardized weights and measures are found in some of the oldest city excavations. Emperor Qin unified China in 210 BC and one element of his administration involved standardizing measurement across his empire. This may seem totally obvious in our modern life, but measurement is technology...

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Version of 24 October 2003