| the Christmas Island GIS online
|
|
|
| Dataset | |
| Title | Pinnacle Field Boundaries |
| Custodian | Geoscience Australia |
| Jurisdiction | Australia |
| Description | |
| 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 |
| Search Word(s) | BOUNDARIES Administrative BOUNDARIES Cultural BOUNDARIES Mining BOUNDARIES National Parks HAZARDS Manmade HUMAN ENVIRONMENT Structures and Facilities |
| Geographic Extent Name(s) | Christmas Island Edition 1 2010 1:30000 - Geoscience Australia GEOCAT 70145 |
| Data Currency | |
| Beginning Date | metadata element in progress |
| Ending Date | metadata element in progress |
| Dataset Status | |
| Progress | Complete |
| Maintenance and Update Frequency | As Required |
| Access | |
| Stored Data Format | DIGITAL - ESRI Shapefiles: Polygon. |
| Available Format Type | DIGITAL - ESRI Shapefiles: Polygon. |
| Access Constraint | Restricted, see contact details below. |
| Data Quality | |
| 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. |
| Positional Accuracy | The positional accuracy is of two standards. In the north-east of the island the areas were digitised using classification methods, so the positional accuracy is the same as in the orthophotography. For the rest of the island the accuracy of the outlines has been determined by the digitising methods. Here the method used was "headsup" digitising at a screen scale. By zooming in to a scale of 1:10,000 it is clear to see the blocky texture of the polygons. Once again it has been digitised from the orthophotography and spatially it is quite accurate. |
| Attribute Accuracy | This metadata element is in progress. |
| Logical Consistency | This metadata element is in progress |
| Completeness | This dataset covers the whole of Christmas Island and at the time of digitising was complete. GA recognises that further work could be undertaken to yield a more up to date and error free data set. |
| Contact Information | |
| Contact Organisation | Geoscience Australia |
| Contact Position | - |
| Mail Address | Cnr Jerrabomberra Ave and Hindmarsh Drive |
| Locality | SYMONSTON |
| State | ACT |
| Country | Australia |
| Postcode | 2609 |
| Telephone | (02) 6249 9479 |
| Facsimile | (02) 6249 9983 |
| Electronic Mail Address | keith.porritt@ga.gov.au |
| Metadata Date | 9-12-2003 |
| Additional Metadata | |
| Projection | UTM (WGS84) zone 48s |
| Printed | June 2012 |