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I'm interested in the geospatial component of what people do...

And everything that people do has a geospatial, or Locative, component. Everything we do, think or experience we do, think or experience somewhere. That Locative piece may seem unimportant, but who is to say?

Consider that our primary source on the lives of many people, including in historical time, is their Middens. That is, their garbage dumps. Who are we to belittle the locative component of even the trivial? * What do we leave behind? Google Images

You know we are different breeds though, right? You guys talk 'location', I talk 'GIS' - is that fair to say?

"After reading A Moveable Feast several times, I'd formed the impression that Paris was huge, and Hemingway was always making these great hikes across town to drink or eat or look at pictures. Now that I've walked between the same places as he did, "I'm impressed at how small and walkable Paris truly is." (a visitor to Paris, retracing Hemingway's steps) Everything was very accessable."

 07:10 < shekhar> there's some really amazing stuff happening
 07:10 < shekhar> we've done gps tracks in many slums
 07:10 < shekhar> and discovered the holes in the municipal development plans
 07:10 < shekhar> by which the builders are profiteering

"The study of the specific effects of the geographical environment, conciously organized or not, on the emotions and behavior of individuals."

*** >Discussion *** Pretty picture? *** Tools? *** Ideas? *** Back to the home page? = The GPS System Attention conservation notice: mostly boring background ahead...will be flipped over quickly * Global Positioning Systems (GPS) ** Global positioning triangulates an unknown location on Earth by correlating time signals from multiple satellites in orbit ** NAVSTAR launched by USAF from 1978 to 1994 ** NAVSTAR constellation employs 24 satellites in 12 medium earth orbits staggered such that five to eight are overhead anywhere on Earth at any time ** NAVSTAR operates in the 1.2 and 1.5 GHz microwave bands * GPS in Theory ** Each GPS satellite transmits its orbital location plus a time-seeded pseudorandom sequence ** A receiver can use this plus the mostly constant speed of light to plot its own location along the edge of a sphere with a radius proportional to the transmission time ** When three of these spheres are plotted, the receiver will be found at the point or region of intersection between them ** A fourth sphere is needed to find elevation * GPS in Practice ** Local bias *** Microwave obstructions *** Multipath and RF noise *** Incorrect local time *** Receiver motion ** More general difficulties *** Ephemeris inaccuracies *** Ionospheric delay *** Selective Availability (off since Oct 2000) * Global Positioning in the Real World ** GPS can be a reliable timekeeping source ** GPS must correct for relativistic time dilation -- about 38 microseconds a day ** Enhancements to GPS *** Differential GPS (DGPS) *** Wide-Area Augmentation System (WAAS) *** European Geostationary Navigation Overlay (EGNOS) ** Other global positioning systems *** LORAN-C *** GLONASS *** Gailleo (due in 2007) * GPS Data Protocols ** Plain ASCII text *** Lat, long, (maybe) altitude, and time ** NMEA-0183 *** ASCII "sentences" over RS-232 at 4800 baud, 8N1 *** Published by the National Marine Electronics Association *** Live navigation and ephemeris data *** Write-only ** Proprietary formats *** e.g. Garmin's GRMN format *** Used to fetch and store tracklogs, waypoints, base maps, etc. *** Read/write * Getting data from your GPS ** Command Line utilities *** gpsbabel - the swiss army chainsaw of gps tools *** Garnix *** gpstrans *** gpsutil * Real-time GPS with gpsd ** Reads NMEA-0183 from a serial port ** Republishes via a simple protocol over TCP/IP ** Intended to make free navigation programs hardware independent ** You can map remote objects in real-time over the 'Net! ** Available from http://pygps.org/gpsd/ * What can you with your GPS data? ** Real-time navigation (gpsdrive) ** Plot it on a basemap ** Use it to georeference other stuff ** Give your Great-Great[...]-Grandfather a GPS * Cell Stumbling * Options for plotting your tracklogs on a base map ** Naive graphing methods (discussed earlier) ** Web-based options like PointMapper, worldKit, etc. ** Simple mapping programs like drawmap ** A full-scale GIS, like GRASS * Geotag your photos from a GPS tracklog ** Time: The universal foreign key ** Adjust for bias in clock difference, time zone ** Linear interpolation between tracklog points * Making your own Garmin base maps ** Get existing aerial photos or base maps ** Add features by hands or from GPS data ** Render the new features to Garmin .IMG format ** We arrived at Burning Man at 5am and found our camp within minutes. ** Tools *** GPSmapper: http://gps.chrisb.org/ *** GPSMapEdit: http://kgy.narod.ru/util/mapedit/mapedit_e.htm * Pretty pictures ** Animation Static Moving * Geospatially Enabled Database ** Postgis * Boom zoom * Yet more... ** bar codes ** Annotating Space ** Speaks to the fundamental simplicity of cartography as a story telling medium. ** Also speaks to the tension between precision and ubiquity in geospatial data and applications... ** "Aircraft navigators have a special interest in maintaining a positive height vector above the surface." = Geographic Information Systems and GIS Data Sources * Geographic Information Systems ** Layers ** Scale and extents ** Data elements *** Points *** Lines *** Areas ** Data Models *** Raster data model *** Vector data model *** "Site" and point data ** "Raster is faster, vector is corrector." -- Joe Berry * Common GIS data formats ** USGS Spatial Data Transfer Standard (SDTS) ** GeoTIFF ** Arc/Info formats ** ESRI shapefiles ** US Census TIGER/Line ** Geographic Markup Language * Manipulating GIS data formats ** Geospatial Data Abstraction Library (GDAL) ** OGR Simple Feature Library ** GDAL converts raster data, OGR handles vector ** Both can be found at http://www.remotesensing.org/gdal/ * US Zip Codes ** No official standard for geocoding ** Can be calculated based on the 'centroid' of the zip code ** US Census Gazetteer has reasonable location and population data for ZIP codes, as well as counties, metro areas, and inhabited places ** Find it at http://www.census.gov/geo/www/gazetteer/places.html * British Post Codes ** The more digits, the more precise your location ** In urban areas, post codes can cover areas as small as 20 meters across ** Free UK postal outcode database at http://www.jibble.org/ukpostcodes/ ** See Tom Coates at the break for more info (Thanks Tom!) * Geographic Name Information Service (GNIS) ** GNIS is a freely downloadable gazetteer of places in the USA. ** Includes lat, long, county name, and the following features:

airport, arch, area, arroyo, bar, basin, bay, beach, bench, bend, bridge, building, canal, cape, cemetery, channel, church, civil, cliff, crater, crossing, dam, falls, flat, forest, gap, geyser, glacier, gut, harbor, hospital, island, isthmus, lake, lava, levee, locale, military, mine, oilfield, other, park, pillar, plain, range, rapids, reserve, reservoir, ridge, school, sea, slope, spring, stream, summit, swamp, tower, trail, tunnel, valley, well, woods

"The RDF data model [is] a handy mechanism for mixing independently created data vocabularies... Unlike vanilla XML, RDF vocabularies can be freely mixed together in data without prior agreement. So you often see ad-hoc combinations of Dublin Core, RSS1, MusicBrainz, RDF-calendar, FOAF, Wordnet, thesaurus, Geo-info etc etc..."

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
	xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#">
  <geo:Point>
    <geo:lat>55.701</geo:lat>
    <geo:long>12.552</geo:long>
  </geo:Point>
</rdf:RDF>

"You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat."