Post on 27-Mar-2015
transcript
John WieczorekMuseum of Vertebrate Zoology
University of California, Berkeley
Georeferencing Introduction: Collaboration to Automation
Georeferencing
Collaborations
Automation
Georeferencing
Collaborations
Automation
What is a georeference?
A numerical description of a place that can be mapped.
What is a georeference?
A numerical description of a place that can be mapped.
What is a georeference?
In other words…
ID Species Locality1 Lynx rufus Dawson Rd. N Whitehorse2 Pudu puda cerca de Valdivia3 Canis lupus 20 mi NW Duluth
9 Ursus arctos Bear Flat, Haines Junction
4 Felis concolor Pichi Trafúl5 Lama alpaca near Cuzco6 Panthera leo San Diego Zoo7 Sorex lyelli Lyell Canyon, Yosemite8 Orcinus orca 1 mi W San Juan Island
What we have:Localities we can read
Darwin Core Location Terms
–higherGeography–waterbody, island, islandGroup–continent, country, countryCode, stateProvince, county, municipality
– locality–minimumElevationInMeters, maximumElevationInMeters, minimumDepthInMeters, maximumDepthInMeters
What we want:Localities we can map
Darwin Core Georeference Terms
– decimalLatitude, decimalLongitude– geodeticDatum– coordinateUncertaintyInMeters– coordinatePrecision– pointRadiusSpatialFit– footprintWKT, footprintSRS,
footprintSpatialFit– georeferencedBy, georeferenceProtocol– georeferenceSources – georeferenceVerificationStatus– georeferenceRemarks
What is a georeference?
A numerical description of a place that can be mapped.
“Davis, Yolo County, California”
“point method”
Coordinates: 38.5463 -121.7425Horizontal Geodetic Datum: NAD27
Data Quality
• data have the potential to be used in ways unforeseen when collected.
• the value of the data is directly related to the fitness for a variety of uses.
• “as data become more accessible many more uses become apparent.” – Chapman 2005
• the MaNIS/HerpNET/ORNIS guidelines follow best practices (Chapman and Wieczorek 2006) to enhance data quality and value
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.
“Davis, Yolo County, California”
“bounding-box method”
Coordinates: 38.5486 -121.754238.545 -121.7394
Horizontal Geodetic Datum: NAD27
“Davis, Yolo County, California”
“point-radius method”
Coordinates: 38.5468 -121.7469Horizontal Geodetic Datum: NAD27Maximum Uncertainty: 8325 m
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 uncertaintiesas well as possible.
“Davis, Yolo County, California”
“shape method”
“20 mi E Hayfork, California”
“probability method”
point easy to produce no data quality
bounding-box simple spatial queriesdifficult quality assessment
point-radius easy quality assessmentdifficult spatial queries
shape accurate representationcomplex, uniform
Method Comparison
probability accurate representationcomplex, non-uniform
MaNIS/HerpNET/ORNIS (MHO) Guidelines
http://manisnet.org/GeorefGuide.html
• uses point-radius representation of georeferences
• circle encompasses all sources of uncertainty about the location
• methodology formalizes assumptions, algorithms, and documentation standards that promote reproducible results
• methods are universally applicable
Darwin Core Georeference Terms
– decimalLatitude, decimalLongitude– geodeticDatum– coordinateUncertaintyInMeters– coordinatePrecision– pointRadiusSpatialFit– footprintWKT, footprintSRS,
footprintSpatialFit– georeferencedBy, georeferenceProtocol– georeferenceSources – georeferenceVerificationStatus– georeferenceRemarks
Georeferencing
Collaborations
Automation
Collaborative DistributedDatabases for Vertebrates
Collaborations
MaNIS Localities Georeferenced
n = 326k localities (1.4M specimens)r = 14 localities/hr (point-radius method)
t = 3 yrs (~40 georeferencers)
ORNIS Localities Georeferenced
n = 267k localities (1.4M specimens)r = 30 localities/hr (point-radius method)
t = 2 yrs (~30 georeferencers)
Scope of the Problem for Natural History Collections
~2.5 Giga-records
Scope of the Problem for Natural History Collections
~2.5 Giga-records
~6 records per locality*
~14 localities per hour*
* based on the MaNIS Project
Scope of the Problem for Natural History Collections
~2.5 Giga-records
~6 records per locality*
~14 localities per hour*
~15,500 years
* based on the MaNIS Project
Scope of the Problem for Natural History Collections
~2.5 Giga-records
~6 records per locality*
~14 (30) localities per hour*
~15,500 (7233) years
* based on the MaNIS (ORNIS) Project
Georeferencing
Collaborations
Automation
http://www.biogeomancer.org
Automation
Combining the Best in Georeferencing
GeoLocate
DIVA-GIS
MaNIS Georeferencing Calculator
BioGeomancer Classic
• Geodetic Datum:defines the position of the origin, scale, shape, and orientation of a 3-dimensional model of the earth. Example: WGS84.
• Coordinate System: defines the “units of measure” of position with respect to the datum. Example: latitude, longitude in degrees, minutes, seconds
Geographical Concepts:
Map Projections:• mathematical
transformations of the 3-D model of the surface of the earth onto a 2-D map.
• there are many (e.g., conical, cylindrical, azimuthal) - they all suffer from distortions (area, shape, distance, or direction), but some preserve areas or distances.
• When measuring distances on paper maps, use an equal distance projection, if available, otherwise understand the implications.
Named place: a place of reference in a locality description. Example: “Davis” in “5 mi N of Davis”
Areal extent: the geographic area covered by a named place (feature). Example: the area inside the boundaries of a town.
Linear extent: the distance from the geographic center to the furthest point of the areal extent of a named place.
Georeferencing Concepts
• Offset: the distance from a named place. Example: “5 mi” in “5 mi NE of Beatty”.
• Heading: the direction from a named place. Example: “NE” in “5 mi NE of Beatty”.
Georeferencing Concepts
• coordinateUncertaintyInMeters:“The horizontal distance (in meters) from the given decimalLatitude and decimalLongitude describing the smallest circle containing the whole of the Location. Leave the value empty if the uncertainty is unknown, cannot be estimated, or is not applicable (because there are no coordinates). Zero is not a valid value for this term.” (from Darwin Core)
• Maximum Error Distance: same as coordinateUncertaintyInMeters, except the units are the same is in the locality description, not necessarily meters.
Georeferencing Concepts
Sources of uncertainty:
Coordinate Uncertainty
Map scale
The extent of the locality
GPS accuracy
Unknown datum
Imprecision in direction measurements
Imprecision in distance measurements (1km vs. 1.1 km)
20° 30’ N 112° 36’ WScale 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
Georeferencing Calculator Example
Locality:0.5 km N of Little mermaid, Copenhagen,
DK
Start with original coordinates for the mermaid:
55° 41' 34.18" N 12° 35' 56.73" E
Then use the Georeferencing Error Calculator to determine the final coordinates AND the uncertainty.
Georeferencing Error Calculator:0.5 km N of Little mermaid, Copenhagen, DK
55° 41' 34.18" N 12° 35' 56.73" E
Capture georeferences in database or spreadsheet (we will use an Excel template for examples)
Georeferencing Templates