| the Christmas Island GIS online
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Index |
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| Dataset | |||||||||||
| Title | 1987 Orthophotography of Christmas Island | ||||||||||
| Custodian | Christmas Island Administration | ||||||||||
| Jurisdiction | Australia | ||||||||||
| Description | |||||||||||
| Abstract | An orthophotograph is a computer image of an aerial photograph in which various distortions due to the landscape and camera lens have been removed. This data is based on the aerial photography of Christmas Island flown in August and September 1987. This has been converted to detailed colour orthophotography (at a 30cm ground resolution) presented as one hundred and fifty-seven 1km tiles for the whole of the Island. On most systems not all the orthophotography will be in this directory, due to limitations of disk size. Most orthophotography of disturbed areas (mining or township) is on the "core" CD-ROM. | ||||||||||
| Search Word(s) | PHOTOGRAPHY AND IMAGERY Aerial PHOTOGRAPHY AND IMAGERY Orthophotography PHOTOGRAPHY AND IMAGERY Raster PHOTOGRAPHY AND IMAGERY Grid |
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| Geographic Extent Name(s) | Christmas Island Edition 2 1995 1:25000 for the Australian Nature Conservation Agency - AUSLIG Mapsheet 94/068 | ||||||||||
| Data Currency | |||||||||||
| Beginning Date | 16AUG1987 | ||||||||||
| Ending Date | 01SEP1987 | ||||||||||
| Dataset Status | |||||||||||
| Progress | Complete | ||||||||||
| Maintenance and Update Frequency | Parks Australia North Christmas Island (PANCI) are endevoring to refly the aerial photography. So far, over two dry seasons in the last few years half of the island has been reflown. Processing to orthophotography has been held off until the flying is complete. See 1997 Orthophotography metadata sheet | ||||||||||
| Access | |||||||||||
| Stored Data Format | DIGITAL - TIFF/TFW. | ||||||||||
| Available Format Type | DIGITAL - TIFF/TFW. | ||||||||||
| Access Constraint | Restricted, see contact details below. | ||||||||||
| Data Quality | |||||||||||
| Lineage | Colour orthophotography for Christmas Island,
with 30cm ground resolution, was achieved by scanning fullsize colour
transparencies of aerial photography. The orthophotography was then
colour balanced and cut into 1km tiles. The quality of the
orthophotographs is impressive, with acceptable resolution down to
1:500 scale.
The following table shows the dates of the flights and their corresponding flight run numbers:
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. |
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| Positional Accuracy | As a general rule the orthophotography is accurate to between 0.3 metres and 0.5 metres in the north east area of the Island. For other disturbed areas of the Island the accuracy ranges from 0.5 metres to 4 metres depending largely on the proximity of, and enclosure by, the aerial photography survey control points ('PP points'). Worst accuracy is in the distant and more inaccessible areas of primary rainforest and these accuracies range from 4 metres to 6 metres with the south west point being an area of lowest accuracy. Also in the orthphto directory are the digitised outer boundaries of some pinnacle fields. | ||||||||||
| Attribute Accuracy | Not Relevant. | ||||||||||
| Logical Consistency | Not Relevant. | ||||||||||
| Completeness | Orthophotos are complete and form a full set of tiles of which only a few may fit onto a CD-ROM. They are based on the aerial photography flown in August - September of 1987. | ||||||||||
| 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 | CIG85 | ||||||||||
| Printed | December 2003 | ||||||||||