Download - Georeferencing of RMCA data
Georeferencing of RMCA data
An TombeurHerpNET workshopRoyal Museum for Central AfricaDecember 2006
Overview
RMCA data GIS processing
– Resources for georeferencing– Visualization of localities– Case identification– Object digitization– Error and extent calculation– Connection with specimens
Conclusion
RMCA data for HerpNET
RMCA will contribute its entire registered amphibian collection (ca. 200,000 specimens) to GBIF and HerpNET
ca. 3000 unique localities mainly from DRC, Burundi, Cameroon, Ivory Coast
and Togo stored in DataPerfect specimen records, linked with locality names
(stations) (collector’s coordinates)
RMCA data: processing
exported to spreadsheet georeferencing according to HerpNET
protocol:– checking of coordinates– addition of radius (maximum error distance)
GIS processing
use of GIS for georeferencing localities and calculation of extent and error
GIS processingStep 1: Resources
maps of DRC, Burundi, Rwanda (mostly 1:200,000)
scanned at 300 dpi detailed recording of map properties:
– scale– projection– datum
GIS processingStep 2: Visualization of localities
Georeferencing of the maps (ca. 5 reference points) with GIS
Use map as background layer Plotting of the (working) localities
Visualization of localitiesExample
GIS processingStep 3: Case identification
HerpNET locality types:– urban area– remote named place– near a named place– river– ...
different calculation of extent & error
each locality: identification of case
GIS processingStep 4: Object digitization
digitization of necessary objects according to case:– case code– station (locality) ID
GIS processing – object digitizationExample
GIS processingStep 5: Extent and error calculation
digitized objects coordinates & extent map specifications error programming of algorithms & output table
point and radius
Example extent calculation (1)Named place (I)
Named place on map
different types
different calculation of extent
Example extent calculation (1)Named place (II)
Example extent calculation (2)Voronoi approach (I)
Voronoi approach
GIS processingStep 6: Connection specimen records
connecting locality ID (with point and radius) with specimen data
export in desired format
Used software
georeferencing of maps, digitizing of objects: MapInfo Pro 7.8
programming error calculation: MapBasic 4 compatible with:
– QGIS– PostGIS
Conclusion
Advantages of GIS processing:– alternative extent & error calculations possible– more precise– in term: faster– easy correction of errors– geographic analysis
Thanks to:
Funding: HerpNET/MVZ Promotor (RMCA): Danny Meirte Co-promotor (RMCA): Patricia Mergen Technical support:
– MVZ: Carol Spencer, Aaron Steele– RMCA: Garin Cael, Bart Meganck, Frank Theeten