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3 second SRTM Derived Digital Surface Model (DSM) version 1.0

Note: This metadata describes the dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2.


Dataset citation

ANZLIC unique identifier: ANZCW0703014216

Title: 3 second SRTM Derived Digital Surface Model (DSM) version 1.0


Custodian

Custodian: Geoscience Australia

Jurisdiction: Australia


Description

Abstract:

The 3 second (~90m) Shuttle Radar Topography Mission (SRTM) derived Digital Surface Model (DSM) Version 1.0 was derived from resampling the 1 arc second (~30m) gridded DSM (ANZCW0703013336) that represents ground surface topography as well as features above the ground such as vegetation and man-made structures. The 1 second DSM was derived from the SRTM data acquired in February 2000, supported by the GEODATA 9 second DEM in void areas and the SRTM Water Body Data. Stripes and voids have been removed from the 1 second SRTM data to provide an enhanced and complete DSM for Australia and near-shore islands. A full description of the methods is in progress (Read et al., in prep). The 3 second DEM was produced for use by government and the public under Creative Commons attribution. Further information can be found in the User Guide.

The 1 second DSM forms the source for the 1 second DEM with vegetation offsets removed (ANZCW0703013355) and the smoothed version (ANZCW0703014016). All 1 second products resampled to 3 seconds are available (DSM; ANZCW0703014216, DEM; ANZCW0703014182, DEM-S; ANZCW0703014217).

These datasets are available freely, with the user being required to agree to the disclaimer at the time of order before the order can be processed. Creative Commons Attribution Australia Licence means data can be shared (copied, distributed, transmitted) or adapted provided you acknowledge the author or licensee. Consult the Creative Commons website for more information. http://creativecommons.org.au

ANZLIC search words:

  • CLIMATE AND WEATHER Climate change
  • ECOLOGY Landscape
  • HAZARDS Flood
  • LAND Topography
  • PHOTOGRAPHY AND IMAGERY Remote Sensing

Spatial domain:

locality map

Geographic extent name: AUSTRALIA EXCLUDING EXTERNAL TERRITORIES - AUS - Australia - Australia

Geographic extent polygon: 113 -10, 154 -10, 154 -44, 113 -44, 113 -10,

Note: The format for each Geographic extent name is: Name - Identifier - Category - Jurisdiction (as appropriate) See GEN Register

Geographic bounding box:
North bounding latitude: -10 °
South bounding latitude: -44 °
East bounding longitude: 154 °
West bounding longitude: 113 °

Data currency

Beginning date: 2000-02-11

Ending date: 2000-02-22


Dataset status

Progress: In Progress

Maintenance and update frequency: Not Known


Access

Stored data format:
DIGITAL - ArcGIS-grid ArcInfo grid Geographic WGS84

Access constraints:

This material is released under the Creative Commons Attribution 3.0 Australia Licence.

Further information on Creative Commons can be found on the website http://creativecommons.org/licenses/by/3.0/au/

Free Data Download

Data quality

Lineage:

Please refer to the User Guide (Geoscience Australia & CSIRO, 2010) for full lineage description.

DSM Ancillary data layers

Four additional data layers were used to make alterations to the raw SRTM data to produce the 1 second DSM:

- A destripe mask indicating which ? x ? degree tiles have been affected by destriping and which have not been destriped

- A striping magnitude layer showing the amplitude of the striping at 0.01 degree (~ 1km) resolution

- A water mask at 1 second resolution showing the cells that are part of the flattened water bodies

- A void mask showing cells that were no-data in the raw SRTM and have been filled using the void filling algorithm

Resampling to 3 seconds

The 1 second SRTM derived Digital Surface Model (DSM) was resampled to 3 seconds of arc (90m) in ArcGIS software using aggregation tool. The 3 second SRTM was converted to integer format for the national mosaic to make the file size more manageable. It does not affect the accuracy of the data at this resolution.

Positional accuracy:

The horizontal positional error is estimated to be three times that of the 1 second products. The 1 second products are the same as the raw SRTM 1 second data, with 90% of tested locations within 7.2 m for Australia. See Rodriguez et al. (2006) for more information on SRTM accuracy.

Attribute accuracy:

Elevation accuracy is essentially three times the raw SRTM 1 second data accuracy, with 90% of tested heights within 9.8m for Australia, which makes the 3 second DSM accuracy about 29m.Errors in height are still mostly due to random variation (noise) that is spatially uncorrelated beyond distances of about 100m (1 second DSM), but there are some broader scale errors. The noise component is typically about +/- 2m (in the 1 second DSM) but in some areas is much larger. See Rodriguez et al. (2006) for more information.

The removal of striping artefacts improves the representation of the landform shape, particularly in low relief areas, but it is not clear whether this also produces an improvement in overall height accuracy. Some striping remains in the data at a much reduced level (mostly less than 0.3m amplitude in the 1 second DSM). Additional artefacts including long-wavelength (~10km) striping have not been corrected (in the 1 second DSM).

Height accuracy is likely to be poorer in areas where voids have been filled using the 9 second DEM, particularly in high relief areas.

Logical Consistency:

The DSM represents elevation. Due to random noise, the relative elevation between adjacent grid cells can be in error by several metres.

All void areas have been filled and there are no discontinuities due to tile boundaries.

The SRTM editing rules relating to water bodies have been respected in the processing: lakes are flat, rivers decline continuously in a downstream direction and sea surfaces are at 0m elevation. Flattened water bodies occupy the same areas as in the original SRTM 1 second data. Grid cells adjacent to water bodies are at least 1cm above the water surface. Void areas within water bodies (small islands not represented in the original SRTM data) are at least 1cm above the water surface over their entire area.

Completeness:

The DSM covers all of continental Australia and near coastal islands land areas including all islands defined by the available SRTM 1 second elevation and SRTM Water Body Data datasets. Some fragments of mainland or pieces of islands may be missing.


Contact information

Contact organisation: Commonwealth of Australia (Geoscience Australia) (GA)
Contact position: Manager Client Services
Mail address: Cnr Jerrabomberra Ave and Hindmarsh Dr
Mail address: GPO Box 378
Locality: Canberra
State: ACT
Country: Australia
Postcode: 2601
Telephone: 02 6249 9966
Facsimile: 02 6249 9960
Electronic mail address: sales@ga.gov.au

Metadata information

Metadata date: 2013-03-08


Additional metadata

Metadata reference XHTML: http://www.ga.gov.au/meta/ANZCW0703014216.html

Metadata reference XML: http://www.ga.gov.au/meta/ANZCW0703014216.xml

Conversion to floating point format

As a by-product of the de-striping process the integer data was converted to floating point format to allow for the continuously varying nature of the striping. Areas where no de-striping was required will contain unaltered integer values, but represented in floating point format for consistency. The three second data was produced as an integer values as the decimal values are well below any affect on the accuracy.

Ancillary data layers distributed with the data

- A water mask at 1 second resolution showing the cells that are part of the flattened water bodies

- JPEG Image of the 3 second DSM

References

Geoscience Australia (2008) GEODATA 9 Second DEM Version 3.

Geoscience Australia and CSIRO Land & Water (2010) 1 Second SRTM Derived Digital Elevation Models User Guide. Version 1.0. Geoscience Australia.

Grohman, G., Kroenung, G., and Strebeck, J. (2006) Filling SRTM voids: The delta surface fill method. Photogrammetric Engineering and Remote Sensing 72 (3), 213-216.

Read, Gallant and Dowling (in prep) Destriping and void filling methods used in SRTM 1 Second processing. See http://www.clw.csiro.au/publications/waterforahealthycountry/index.html for progress.

Rodriguez, E., Morris, C.S., and Belz, J.E. (2006) A global assessment of the SRTM performance. Photogrammetric Engineering and Remote Sensing 72 (3), 249-260.

Sibson, R. (1981) A brief description of natural neighbour interpolation. In V. Barnet, editor, Interpreting Multivariate Data, pages 21-36. John Wiley & Sons, Chichester.

Slater, J.A., Garvey, G., Johnston, C., Haase, J., Heady, B., Kroenung, G., and Little, J. (2006) The SRTM data "finishing" process and products. Photogrammetric Engineering and Remote Sensing 72 (3), 237-247.

Authors:Wilson, N. Tickle, P. Gallant, J. Dowling, T. Read, A.
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