Georeferencing:Collaboration and Automation
John Wieczorek1
Reed Beaman2
1Museum of Vertebrate ZoologyUniversity of California, Berkeley
2Center for Biodiversity ResearchUniversity of Kansas
Caveat:I’m going to over-simplify
everything.
Warning:Apertem os Cintos
Fasten your seat belts
What is georeferencing?
Georeferencing is the expression of a
terrestrial spatial description in
coordinates within a
frame of reference
Terrestrial Spatial Descriptions:
• Bakersfield• 10 mi E (by air) Bakersfield• 5 mi from Bakersfield• 2 mi E and 1.5 mi N of Bakersfield• 13 mi E (by road) Bakersfield• 10.2 mi E of Bakersfield• E of Bakersfield T29S R29E
Sec.34
Coordinates
• Points (have no spatial footprint)
• Shapes (have bounded footprint)
Polygons
Multipolygons
Coordinate Systems
• decimal degrees35.3733 -119.0178
• degrees minutes seconds35 22 23.88 N, 119 1 4.08 W
• degrees, decimal minutes 35 22.398 N, 119 1.068 W
• UTM Zone 11S 316695E 3916111N
• Innumerable other grid-based systems
Frames of Reference
• Australian Geodetic 1984
• Japanese Geodetic Datum 2000
• North American Datum 1983
• South American 1969
• World Geodetic System 1984
Geodetic Datums
• … over 100 others
Why is the datum important?
What is an ideal georeference?
I propose that it is a shape, with a frame of reference, which exactly describes the spatial extent of a terrestrial location.
The answer depends on the questions you want to address.
“The Shape Method”
“Davis, Yolo County, California”
“Davis, Yolo County, California”
Is this method currently practical?
• Requires sophisticated software to capture these data.
• Requires database capabilities beyond the scope of many collections
• Requires baseline digital data that are neither freely, nor globally available.
The remedy is costly.
What is practical?
Describe spatial extent using elements that can be captured and stored by anyone using current technology.
One possible solution
Describe the locality using one set of coordinates, the datum, and a bounding radius.
“The Point-Radius Method”
“Davis, Yolo County, California”
“Davis, Yolo County, California”
Coordinates: 35.32443 -119.32343Horizontal Geodetic Datum: NAD27Maximum Error Distance: 8325 m
Advantages
This remedy is relatively inexpensive.
• Describes the locality in a minimal element set.
• Obviates the need for investment in new technology.
• Establishes a maximum spatial scale of the locality.
• Does enable spatial visualization and a broad range of analytical applications
Disadvantages
The remedy will remain just as costly as before.
• This solution does not contribute toward the ideal solution.
• There may be future applications for spatial footprints that cannot be met by the data produced by the Point-Radius Method.
Who is georeferencing?
Who isn’t, and why not?
Who is georeferencing?
• MaNIS – 17 mammal collections; institutions in Canada, Mexico and the United States; global holdings; 1.4M specimens; 284k localities; 3 years; started Sep 2001.
http://elib.cs.berkeley.edu/manis
• HerpNet – 37 North American herpetological collections; global holdings; ca. 3M specimens; 5 years; first georeferencing North and Central American localities; starts 2003.
How are we georeferencing?
How are we georeferencing?
Collaboration
http://elib.cs.berkeley.edu/manis/search.shtml
Advantages
• Reduces overall cost of supplies – no duplication• Expands the pool of resources – geographic
expertise and reference material• Increases georeferencing rates – economy of
scale• Promotes standardization – methods• Increases skills in a community• Increases exposure and awareness inside and
outside of a community
Disadvantages
• Vulnerable to procrastinators, cheaters, and numbskulls.
• Can distance georeferencing process from useful primary resources (e.g., field notes).
• Introduces time sensitivity to the georeferencing process
• Requires project-level management
One way to improve upon the georeferencing process will be
to collaborate with a distributed query mechanism
already in place.
Reed will talk about another way we hope to improve the
georeferencing process.
Special Thanks
CONABIOBell Museum
Kansas State UniversitySan Diego Natural History
MuseumA. Townsend Peterson1
1University of Kansas Natural History Museum