Weddell seal reporting grid of the Vestfold Hills, Antarctica
Positional Accuracy 1 m to 10 m There are several sources of error: 1. Inaccuracies in the original map, both in the shape of the coastline and in the geodetic framework. In 1958, the geodetic control for the aerial photography would have been done using astronomical observations. 2. Inaccuracies in...
id |
ftands:oai:ands.org.au::687259 |
---|---|
record_format |
openpolar |
institution |
Open Polar |
collection |
Research Data Australia (Australian National Data Service - ANDS) |
op_collection_id |
ftands |
language |
unknown |
topic |
biota oceans ISLANDS EARTH SCIENCE BIOSPHERE TERRESTRIAL ECOSYSTEMS SEALS/SEA LIONS/WALRUSES BIOLOGICAL CLASSIFICATION ANIMALS/VERTEBRATES MAMMALS CARNIVORES Computer > Computer MAPS AMD/AU CEOS AMD CONTINENT > ANTARCTICA GEOGRAPHIC REGION > POLAR |
spellingShingle |
biota oceans ISLANDS EARTH SCIENCE BIOSPHERE TERRESTRIAL ECOSYSTEMS SEALS/SEA LIONS/WALRUSES BIOLOGICAL CLASSIFICATION ANIMALS/VERTEBRATES MAMMALS CARNIVORES Computer > Computer MAPS AMD/AU CEOS AMD CONTINENT > ANTARCTICA GEOGRAPHIC REGION > POLAR Weddell seal reporting grid of the Vestfold Hills, Antarctica |
topic_facet |
biota oceans ISLANDS EARTH SCIENCE BIOSPHERE TERRESTRIAL ECOSYSTEMS SEALS/SEA LIONS/WALRUSES BIOLOGICAL CLASSIFICATION ANIMALS/VERTEBRATES MAMMALS CARNIVORES Computer > Computer MAPS AMD/AU CEOS AMD CONTINENT > ANTARCTICA GEOGRAPHIC REGION > POLAR |
description |
Positional Accuracy 1 m to 10 m There are several sources of error: 1. Inaccuracies in the original map, both in the shape of the coastline and in the geodetic framework. In 1958, the geodetic control for the aerial photography would have been done using astronomical observations. 2. Inaccuracies in the 'modern' (UTM) coastline. There are known to be inaccuracies in the map from which this was digitised and there are question marks about the quality of the digitising. 3. Inaccuracies in plotting the location data in the field which were presumably done by estimating position from local landmarks rather than by measurement eg compass bearing. 4. The correction of the offset manually is only a 'best fit' for all points. Values provided in temporal coverage are approximate only. This is a digital version of the grid reference map used to plot all sightings of Weddell seals in the Vestfold Hills. The point of origin is the same as the original map and each grid cell is numbered with the same numbering scheme. This can be used to plot any data using the same numbering scheme by joining (ArcInfo) or linking (ArcView) records to this coverage's polygon attribute table (pat) through the item GRIDREF. The original map was a 1:100 000 map of the Vestfolds, provided by Harry Burton, with a grid drawn over it. The grid references were given as either six or four figure values on which field scientists are to plot their data. This map has the following Antarctic Division drawing reference number: M/75/05A Some research with John Cox revealed that this grid was drawn up over a map digitised from another map with the following specifications: Scale 1: 100 000 Date: 1958 (reprinted 1972) Projection: Polyconic Published by: Division of National Mapping, Canberra Reference number: NMP/58/084 Data are referenced to a 'grid' of 1 minute spacing in x axis and 30 second spacing in y axis. The point of origin is apparently 68 20 S 77 48 E. There are 45 rows and 47 columns. The 'grid reference' is in fact in geographic coordinates (but using arbitrary units) so the projection of the original map became irrelevant. The procedure adopted to create a new digital grid was as follows: (Carried out in Arc/Info) 1. Generate a coverage using the original 'grid references'. 2. Tics were also generated using the corners of the 'grid reference' system. 3. A new coverage was created with tics at the same locations but given the true latitude/longitude vales. 4. The original coverage was then transformed to the new coverage based on the new tic values. 5. The new coverage was then projected from geographic coordinates to UTM metres. The data locations were then viewed in Arc/Info using a coverage of the coastline supplied by the Mapping Officer, Antarctic Division. This had previously been determined to be in the UTM projection. An offset was clearly visible between the data locations and the coastline. In order to determine whether the offset was more or less uniform, ten locations were plotted from the original data onto the original map using the 'grid'. Finally a manual corrected was made by moving all the data locations by a uniform distance of 508 metres north and 68 metres west. Information from John van den Hoff, February 2019: The grid cells were originally labelled from 1 to 47 along the x axis and 1 to 45 along the y axis. The four digit values in the GRIDREF field of the attribute table are the x value followed by the y value. To avoid confusion between x and y values, the grid was later revised so that the y values were prefixed with a ‘1’ so for example 01 became 101. The GRIDREF_X and GRIDREF_Y fields have the x and y values of the revised grid. This needs to be kept in mind when data is sourced from field books. The map shows the revised grid. |
author2 |
AADC (originator) AU/AADC > Australian Antarctic Data Centre, Australia (resourceProvider) |
format |
Dataset |
title |
Weddell seal reporting grid of the Vestfold Hills, Antarctica |
title_short |
Weddell seal reporting grid of the Vestfold Hills, Antarctica |
title_full |
Weddell seal reporting grid of the Vestfold Hills, Antarctica |
title_fullStr |
Weddell seal reporting grid of the Vestfold Hills, Antarctica |
title_full_unstemmed |
Weddell seal reporting grid of the Vestfold Hills, Antarctica |
title_sort |
weddell seal reporting grid of the vestfold hills, antarctica |
publisher |
Australian Ocean Data Network |
url |
https://researchdata.ands.org.au/weddell-seal-reporting-hills-antarctica/687259 https://data.aad.gov.au/metadata/records/Wed_map https://data.aad.gov.au/eds/4851/download http://data.aad.gov.au/aadc/mapcat/display_map.cfm?map_id=13292 https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=89 https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=95 http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=Wed_map |
op_coverage |
Spatial: northlimit=-68.3216; southlimit=-68.7231; westlimit=77.7467; eastLimit=78.6245 Temporal: From 1989-09-30 to 1990-03-31 |
long_lat |
ENVELOPE(-112.453,-112.453,57.591,57.591) ENVELOPE(166.733,166.733,-72.550,-72.550) ENVELOPE(77.7467,78.6245,-68.3216,-68.7231) |
geographic |
Antarctic Vestfold Hills Weddell Vestfold The ''Y'' Burton |
geographic_facet |
Antarctic Vestfold Hills Weddell Vestfold The ''Y'' Burton |
genre |
Antarc* Antarctic Antarctica Weddell Seal Weddell Seals walrus* |
genre_facet |
Antarc* Antarctic Antarctica Weddell Seal Weddell Seals walrus* |
op_source |
https://data.aad.gov.au |
op_relation |
https://researchdata.ands.org.au/weddell-seal-reporting-hills-antarctica/687259 ca02315a-f969-40c3-bd1b-a07c3d78000e https://data.aad.gov.au/metadata/records/Wed_map https://data.aad.gov.au/eds/4851/download http://data.aad.gov.au/aadc/mapcat/display_map.cfm?map_id=13292 https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=89 https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=95 http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=Wed_map |
_version_ |
1766245731347202048 |
spelling |
ftands:oai:ands.org.au::687259 2023-05-15T13:46:56+02:00 Weddell seal reporting grid of the Vestfold Hills, Antarctica AADC (originator) AU/AADC > Australian Antarctic Data Centre, Australia (resourceProvider) Spatial: northlimit=-68.3216; southlimit=-68.7231; westlimit=77.7467; eastLimit=78.6245 Temporal: From 1989-09-30 to 1990-03-31 https://researchdata.ands.org.au/weddell-seal-reporting-hills-antarctica/687259 https://data.aad.gov.au/metadata/records/Wed_map https://data.aad.gov.au/eds/4851/download http://data.aad.gov.au/aadc/mapcat/display_map.cfm?map_id=13292 https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=89 https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=95 http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=Wed_map unknown Australian Ocean Data Network https://researchdata.ands.org.au/weddell-seal-reporting-hills-antarctica/687259 ca02315a-f969-40c3-bd1b-a07c3d78000e https://data.aad.gov.au/metadata/records/Wed_map https://data.aad.gov.au/eds/4851/download http://data.aad.gov.au/aadc/mapcat/display_map.cfm?map_id=13292 https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=89 https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=95 http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=Wed_map https://data.aad.gov.au biota oceans ISLANDS EARTH SCIENCE BIOSPHERE TERRESTRIAL ECOSYSTEMS SEALS/SEA LIONS/WALRUSES BIOLOGICAL CLASSIFICATION ANIMALS/VERTEBRATES MAMMALS CARNIVORES Computer > Computer MAPS AMD/AU CEOS AMD CONTINENT > ANTARCTICA GEOGRAPHIC REGION > POLAR dataset ftands 2020-01-05T21:08:27Z Positional Accuracy 1 m to 10 m There are several sources of error: 1. Inaccuracies in the original map, both in the shape of the coastline and in the geodetic framework. In 1958, the geodetic control for the aerial photography would have been done using astronomical observations. 2. Inaccuracies in the 'modern' (UTM) coastline. There are known to be inaccuracies in the map from which this was digitised and there are question marks about the quality of the digitising. 3. Inaccuracies in plotting the location data in the field which were presumably done by estimating position from local landmarks rather than by measurement eg compass bearing. 4. The correction of the offset manually is only a 'best fit' for all points. Values provided in temporal coverage are approximate only. This is a digital version of the grid reference map used to plot all sightings of Weddell seals in the Vestfold Hills. The point of origin is the same as the original map and each grid cell is numbered with the same numbering scheme. This can be used to plot any data using the same numbering scheme by joining (ArcInfo) or linking (ArcView) records to this coverage's polygon attribute table (pat) through the item GRIDREF. The original map was a 1:100 000 map of the Vestfolds, provided by Harry Burton, with a grid drawn over it. The grid references were given as either six or four figure values on which field scientists are to plot their data. This map has the following Antarctic Division drawing reference number: M/75/05A Some research with John Cox revealed that this grid was drawn up over a map digitised from another map with the following specifications: Scale 1: 100 000 Date: 1958 (reprinted 1972) Projection: Polyconic Published by: Division of National Mapping, Canberra Reference number: NMP/58/084 Data are referenced to a 'grid' of 1 minute spacing in x axis and 30 second spacing in y axis. The point of origin is apparently 68 20 S 77 48 E. There are 45 rows and 47 columns. The 'grid reference' is in fact in geographic coordinates (but using arbitrary units) so the projection of the original map became irrelevant. The procedure adopted to create a new digital grid was as follows: (Carried out in Arc/Info) 1. Generate a coverage using the original 'grid references'. 2. Tics were also generated using the corners of the 'grid reference' system. 3. A new coverage was created with tics at the same locations but given the true latitude/longitude vales. 4. The original coverage was then transformed to the new coverage based on the new tic values. 5. The new coverage was then projected from geographic coordinates to UTM metres. The data locations were then viewed in Arc/Info using a coverage of the coastline supplied by the Mapping Officer, Antarctic Division. This had previously been determined to be in the UTM projection. An offset was clearly visible between the data locations and the coastline. In order to determine whether the offset was more or less uniform, ten locations were plotted from the original data onto the original map using the 'grid'. Finally a manual corrected was made by moving all the data locations by a uniform distance of 508 metres north and 68 metres west. Information from John van den Hoff, February 2019: The grid cells were originally labelled from 1 to 47 along the x axis and 1 to 45 along the y axis. The four digit values in the GRIDREF field of the attribute table are the x value followed by the y value. To avoid confusion between x and y values, the grid was later revised so that the y values were prefixed with a ‘1’ so for example 01 became 101. The GRIDREF_X and GRIDREF_Y fields have the x and y values of the revised grid. This needs to be kept in mind when data is sourced from field books. The map shows the revised grid. Dataset Antarc* Antarctic Antarctica Weddell Seal Weddell Seals walrus* Research Data Australia (Australian National Data Service - ANDS) Antarctic Vestfold Hills Weddell Vestfold The ''Y'' ENVELOPE(-112.453,-112.453,57.591,57.591) Burton ENVELOPE(166.733,166.733,-72.550,-72.550) ENVELOPE(77.7467,78.6245,-68.3216,-68.7231) |