Authors / CoAuthors
Unknown
Abstract
The pinnacle field boundaries dataset covers the whole of Christmas Island. It contains polygons that have been digitised around areas or fields of pinnacles. The polygons were digitised in two goes. The first was a animated process initiated by Geoscience Australia using Erdas software, this resulted in high resolution polygons located over the north east portion of Christmas Island. This turned out to be a slow process so the task was then taken up by manual digitising off the screen using orthphotography as a back drop. This method was used in digitising the rest of the island. The lack resolution for these polygons can be seen by their blocky appearance, these are visible at scales of 1:10,000. The pinnacle boundaries shapefile is pinclbnd.shp and contains the following fields: Field Type Width Decimal ---------------------------------------------------Shape FIELD_SHAPEPOLY 8 0 Area FIELD_DECIMAL 12 3 Perimeter FIELD_DECIMAL 12 3 Altpinn_cn FIELD_DECIMAL 11 0 Altpinn_cn FIELD_DECIMAL 11 0 Single_tre FIELD_CHAR 16 0 Dxf_color FIELD_DECIMAL 2 0 Dxf_thickn FIELD_DECIMAL 12 3 Dxf_type FIELD_CHAR 10 0 Dxf_elevat FIELD_DECIMAL 12 3 Dxf_angle FIELD_DECIMAL 12 3 Dxf_size FIELD_DECIMAL 12 3 Dxf_text FIELD_CHAR 80 0 Dxf_attrib FIELD_CHAR 16 0 Dxf_iid FIELD_DECIMAL 11 0 Hectares FIELD_DECIMAL 16 3
Product Type
dataset
eCat Id
81805
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
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- AU-ACT
- 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 production of pinnacle boundaries was first initiated by AGSO in 1996. These boundaries were constructed around the pinnacle fields by use of an automated classification utility associated with the Erdas program. The process of classifying regions of pinnacles was very time consuming and so was taken over by the mines surveyors assistant (James Keogh). GA completed digitising the NE part of Christmas Island using Erdas software. The resolution obtained by this method allows polygon outlines to appear smooth to a scale of at least 1:500. The rest of the Island was completed by way of headsup digitising (on screen digitising) using the orthophotography as the background. James Keogh completed the task of digitising around the pinnacle fields. The typical scale that provides a smooth outline is no better than 1:10,000. As part of the Christmas Island airport extention project in November 2002, GA added eight previously undigitised pinnacle fields to the original shapefile. Six fields north and two to the south of the airport. Upon reviewing the field closest to the southern section of the runway with the 2000 Airborne Laser Scanning, it was expanded by 17,000m squared. 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
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