Authors / CoAuthors
Unknown
Abstract
This dataset has been digitised from the 1:25000 vegetation map of Christmas Island (accompanying Mitchells 1985 report). The vector version was completed on behalf of Parks Australia Christmas Island. Geoscience Australia used ArcInfo to heads-up digitise a scanned version of the map. Once digitised the arcs were built into polygons and the map was attributed based on the Geoscience Australia data dictionary guidelines. All information relating to vegetation boundaries was extracted from the map and incorporated in the table. The fields that were used follow: Alias Type Width Decimal -----------------------------------------------Shape FIELD_SHAPEPOLY 80Ufi FIELD_DECIMAL 6 0 - unique numberArea FIELD_DECIMAL 18 5Perimeter FIELD_DECIMAL 18 5Code FIELD_CHAR 80 0 - Vegetation unit (map symbol)Descript FIELD_CHAR 64 0 - Description of unitCategories FIELD_CHAR 50 0 - vegetation categoriesFeature FIELD_CHAR 12 0 - (GA field)Plotrank FIELD_DECIMAL 1 0 - (GA field)
Product Type
dataset
eCat Id
81823
Contact for the resource
Custodian
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GIS Dataset
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2003-01-01T00:00:00
Creation Date
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Purpose
Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
Lineage
The map originally accompanied Mitchells 1985 report, and was based on the geology and topography map of Christmas Island by J. Barrie in 1966. This map was scanned and translated to the CIG85 projection. The scanned map was included in the Christmas Island GIS. It was digitised by Geoscience Australia in mid October 2001 on behalf of Parks Australia North Christmas Island. Newveg.shp is the revised version of Vegetation.shp. Dr. Pete Green a Research Fellow from EA created this .shp file by taking the original vegetation file, making all the vegetation types semi-transparent, and superimposing this theme over a composite aerial photograph of the island (Christmas.ers, generated from the 1987 aerial photos). Dr. Green then adjusted the position of the clearing boundaries (category SV) around all previously mined fields, expanded these polygons to include all major roads, and added and subtracted polygons as required. In all cases Dr. Green tried to pick the original boundary of the clearing - there has been substantial regrowth around the borders of some mined fields, but this regrowth can be distinguished from the adjacent forest by its more regular canopy. Dr. Green made a concerted effort to ONLY adjust the position of forest/clearing boundaries, and NOT forest/forest boundaries. The aerial photos are excellent for judging the position of the former, but we have no prior evidence for adjusting the latter - as far as Dr. Green knows, the positions of forest/forest boundaries have never been ground-truthed. Where boundaries were indistinct on Christmas.ers, Dr. Green occasionally made reference to two sets of black and white aerial photographs of the island taken in 1976 and 1981. In September 2003 this dataset was converted to the MGA(GDA94) projection using an x y shift (550015 = x, 8780001 = y) on the CIG85 projection.
Parent Information
Extents
[-10.5667, -10.4167, 105.5333, 105.7167]
Reference System
Spatial Resolution
Service Information
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