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