What you don¢â‚¬â„¢t know can hurt you: uncertainties in georeferencing 2009-04-08¢  What you don¢â‚¬â„¢t know

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  • What you don’t know can hurt you: uncertainties in georeferencing

    John Wieczorek Museum of Vertebrate Zoology

    University of California, Berkeley

  • Uncertainties

    What comes out of a system depends on:

    a)

    what goes into it b)

    what you ask of it

    c)

    what happens in between

  • What species occur where?

    Basis for:

    conservation bio-prospecting entertainment survival?

  • What species

    occur where?

    species identification

  • What species occur where?

    occurrence location

  • Problem: most original data are in textual form

    Problem: collection resources are scarce and can’t support large-scale digitization

    What species occur where? occurrence location

  • What species

    occur where?

    What can Biodiversity Informatics do?

    Taxonomic Resolution Services

  • What can Biodiversity Informatics do?

    Taxonomic Resolution Services

    What species occur where?

    Georeferencing Services

  • ID Species Locality 1 Lynx rufus Dawson Rd. N Whitehorse 2 Pudu

    puda cerca

    de Valdivia

    3 Canis

    lupus 20 mi NW Duluth

    9 Ursus

    arctos Bear Flat, Haines Junction

    4 Felis

    concolor Pichi

    Trafúl 5 Lama alpaca near Cuzco 6 Panthera

    leo San Diego Zoo

    7 Sorex

    lyelli Lyell Canyon, Yosemite 8 Orcinus

    orca 1 mi W San Juan Island

    What we have: Localities we can read

  • What we want: Localities we can map

  • Integration –

    Species Pages

  • What is a georeference?

    A numerical description of a place that can be mapped.

    Presenter Presentation Notes testing slide 2

  • “Davis, Yolo County, California”

    “point method”

    Coordinates: 38.5463 -121.7425 Horizontal Geodetic Datum: NAD27

    Presenter Presentation Notes testing slide 2

  • What is an acceptable georeference?

    A numerical description of a place that can be mapped

    and that describes the spatial extent of a locality

    and its associated uncertainties.

    Presenter Presentation Notes testing slide 2

  • 1) Map inaccuracy

    2) Extent of the reference

    3) Coordinate imprecision

    4) Undocumented datum

    5) Distance imprecision

    6) Direction imprecision

    Scale Uncertainty (ft) Uncertainty (m)

    1:1,200 3.3 ft 1.0 m

    1:2,400 6.7 ft 2.0 m

    1:4,800 13.3 ft 4.1 m

    1:10,000 27.8 ft 8.5 m

    1:12,000 33.3 ft 10.2 m

    1:24,000 40.0 ft 12.2 m

    1:25,000 41.8 ft 12.8 m

    1:63,360 106 ft 32.2 m

    1:100,000 167 ft 50.9 m

    1:250,000 417 ft 127 m

    Sources of uncertainty

  • “Davis, Yolo County, California”

    “bounding-box method”

    Coordinates: 38.5486 -121.7542 38.5450 -121.7394

    Horizontal Geodetic Datum: NAD27

    Presenter Presentation Notes testing slide 2

  • “Davis, Yolo County, California”

    “point-radius method”

    Coordinates: 38.5468 -121.7469 Horizontal Geodetic Datum: NAD27 Maximum Uncertainty: 8325 m

    Presenter Presentation Notes testing slide 2

  • What is an ideal georeference?

    A numerical description of a place that can be mapped

    and that describes the spatial extent of a locality

    and its associated uncertainties as well as possible.

    Presenter Presentation Notes testing slide 2

  • “Davis, Yolo County, California”

    “shape method”

    Presenter Presentation Notes testing slide 2

  • “20 mi E Hayfork, California”

    “probability method”

  • point easy to produce no data quality

    bounding-box simple spatial queries difficult quality assessment

    point-radius easy quality assessment difficult spatial queries

    shape accurate representation complex, uniform

    Method Comparison

    probability accurate representation complex, non-uniform

  • Global Biodiversity Information Facility (GBIF)

    Point-radius Method

  • “Manual”

    Georeferencing Tools

    http://manisnet.org/gci2.html

  • Semi-automated Georeferencing Tools

    http://bg.berkeley.edu/latest

  • (a)

    (d)(c)

    (b)

    Rowe, 2005. Elevational

    gradient analysis of

    historical museum specimens: a cautionary tale

  • Rowe, 2005. Elevational

    gradient analysis of

    historical museum specimens: a cautionary tale

  • What species occur where? Conclusions:

    1)

    We can help users find relevant records

    2) We can help users assess data quality and fitness for use

    3) In the end, users must exercise due diligence. Without 1) and 2), they can’t.

  • Slide Number 1 Slide Number 2 Slide Number 3 Slide Number 4 Slide Number 5 Slide Number 6 Slide Number 7 Slide Number 8 What we have:�Localities we can read Slide Number 10 Slide Number 11 What is a georeference? Slide Number 13 What is an acceptable georeference? Slide Number 15 Slide Number 16 Slide Number 17 What is an ideal georeference? Slide Number 19 Slide Number 20 Method Comparison Slide Number 22 Slide Number 23 Slide Number 24 Slide Number 25 Slide Number 26 Slide Number 27 Slide Number 28

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