Product catalogue
DEA Geometric Median and Median Absolute Deviation (Landsat)
Background
When deriving information from satellite images it may be beneficial to see how an area usually looks over a given year rather than how it was viewed at a single point in time. Other useful interpretations include how dynamic or variable the Australian landscape is over any given year, especially to help with understanding how the landscape changes, or to discriminateparts of the landscape that stay the same throughout the year (like bare rock), from those areas that go through big changes in cover (such as cropping areas).
By understanding general conditions (which can be thought of as "average" for the year) and the different patterns of variation, we can characterise various types of land cover and land use, and detect changes of significance in the landscape.
The Geometric Median provides information on the general conditions of the landscape for a given year.
The Median Absolute Deviation provides information on how the landscape is changing in the same year.
The DEA GeoMAD product combines the Geometric Median and the Median Absolute Deviation in a single, annually produced package.
What this product offers
This product provides statistical tools to exploit the time series of Earth observation data available in Digital Earth Australia, providing annual images of general conditions and how much an area changes for a given year.
Thegeomedian part of the product provides an "average" cloud-free image over the given year. The geomedian image is calculated with a multi-dimensional median, using all the spectral measurements from the satellite imagery at the same time in order to maintain the relationships among the measurements.
The median absolute deviation part of the product uses three measures of variance, each of whichprovides a "second order" high dimensional statistical compositefor the given year. The three variance measures show how much an area varies from the "average" in terms of "distance" based on factors such as brightness and spectra:
Euclidean distance (EMAD)
Cosine (spectral) distance (SMAD)
Bray Curtis dissimilarity (BCMAD)
Together, they provide information on variance in the landscape over the given year and are useful for change detection applications.
Simple
Identification info
- Date (Creation)
- 2021-06-15T11:33:12
- Date (Publication)
- 2022-02-02T01:54:16
- Date (Revision)
- 2025-03-18
- Edition
-
3.1.0
- Citation identifier
- Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/146261
- Citation identifier
- Digital Object Identifier/https://dx.doi.org/10.26186/146261
- Cited responsible party
-
Role Organisation / Individual Name Details Owner Commonwealth of Australia (Geoscience Australia)
Voice Principal investigator Mueller, N.
PSCD Internal Contact Publisher Commonwealth of Australia (Geoscience Australia)
Voice
- Status
- On going
- Point of contact
-
Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Jorand, C.
Space Division Internal Contact Resource provider Space Division
External Contact
- Topic category
-
- Geoscientific information
Extent
))
Temporal extent
- Time period
- 1986-08-15
- Maintenance and update frequency
- Annually
Resource format
- Title
-
Product data repository: Various Formats
- Protocol
-
FILE:DATA-DIRECTORY
- Name of the resource
-
Data Store directory containing the digital product files
- Description
-
Data Store directory containing one or more files, possibly in a variety of formats, accessible to Geoscience Australia staff only for internal purposes
- theme.ANZRC Fields of Research.rdf
-
-
EARTH SCIENCES
-
- Theme
-
-
satellite images
-
Geomedian
-
Geometric median
-
Median Absolute Deviation
-
- Keywords
-
-
Published_External
-
Resource constraints
- Title
-
Creative Commons Attribution 4.0 International Licence
- Alternate title
-
CC-BY
- Edition
-
4.0
- Access constraints
- License
- Use constraints
- License
- Other constraints
-
CC BY Attribution 4.0 International License
Resource constraints
- Title
-
Australian Government Security ClassificationSystem
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
Associated resource
- Association Type
- Is composed of
- Title
-
DEA GeoMAD (Landsat)
Identifier
- Description
-
CMI record of DEA GeoMAD (Landsat), technical name: DEA Geometric Median and Median Absolute Deviation (Landsat)
- Language
- English
- Character encoding
- UTF8
Distribution Information
- Distributor contact
-
Role Organisation / Individual Name Details Distributor Commonwealth of Australia (Geoscience Australia)
Voice
- OnLine resource
-
DEA GeoMAD data for annual Landsat 5 observations
DEA GeoMAD data for annual Landsat 5 observations
- Distribution format
-
- OnLine resource
-
DEA GeoMAD for annual Landsat 7 observations
DEA GeoMAD for annual Landsat 7 observations
- Distribution format
-
- OnLine resource
-
DEA GeoMAD for annual Landsat 8 observations
DEA GeoMAD for annual Landsat 8 observations
- Distribution format
-
Resource lineage
- Statement
-
When deriving information from satellite images it may be beneficial to see how an area usually looks over a given year rather than how it was viewed at a single point in time. Other useful interpretations include how dynamic or variable the Australian landscape is over any given year, especially to help with understanding how the landscape changes, or to discriminateparts of the landscape that stay the same throughout the year (like bare rock), from those areas that go through big changes in cover (such as cropping areas).
By understanding general conditions (which can be thought of as "average" for the year) and the different patterns of variation, we can characterise various types of land cover and land use, and detect changes of significance in the landscape.
The Geometric Median provides information on the general conditions of the landscape for a given year.
The Median Absolute Deviation provides information on how the landscape is changing in the same year.
The DEA GeoMAD product combines the Geometric Median and the Median Absolute Deviation in a single, annually produced package.
- Hierarchy level
- Dataset
- Description
-
Please refer to the lineage section.
Reference System Information
- Reference system identifier
- EPSG/GDA94 (geocentric) (EPSG:4348)
Metadata constraints
- Title
-
Australian Government Security Classification System
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
Metadata
- Metadata identifier
-
urn:uuid/9eca720c-24fb-49b7-bc2f-42fe2362c162
- Title
-
GeoNetwork UUID
- Language
- English
- Character encoding
- UTF8
- Contact
-
Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Glitsos, B.
Space Division Internal Contact
Type of resource
- Resource scope
- Dataset
Alternative metadata reference
- Title
-
Geoscience Australia - short identifier for metadata record with uuid
- Citation identifier
- eCatId/146261
- Date info (Creation)
- 2025-04-17T02:01:10.256Z
- Date info (Creation)
- 2025-04-17T01:32:54.48Z
- Date info (Creation)
- 2025-04-07T04:38:59.65Z
- Date info (Creation)
- 2025-04-07T04:28:26.443Z
- Date info (Creation)
- 2021-06-15T11:33:12+10:00
- Date info (Revision)
- 2025-04-17T02:12:18.115Z
Metadata standard
- Title
-
AU/NZS ISO 19115-1:2014
Metadata standard
- Title
-
ISO 19115-1:2014
Metadata standard
- Title
-
ISO 19115-3
- Title
-
Geoscience Australia Community Metadata Profile of ISO 19115-1:2014
- Edition
-
Version 2.0, September 2018
- Citation identifier
- https://pid.geoscience.gov.au/dataset/ga/122551