DEA Geometric Median and Median Absolute Deviation - Landsat 7 3.1.0

info

This dataset is part of a Publisher Catalog, and not managed by Google. Contact Geoscience Australia for bugs or view more datasets from the Geoscience Australia Catalog. Learn more about Publisher datasets.

Catalog Owner

Geoscience Australia

Dataset Availability

2000-01-01T00:00:00Z–2021-01-01T00:00:00Z

Dataset Provider

Geoscience Australia NGIS

Contact

https://www.ga.gov.au/contact-us

Earth Engine Snippet

ee.ImageCollection("projects/geoscience-aus-cat/assets/ga_ls7e_nbart_gm_cyear_3")

Tags

australia ga geoscience-aus-cat landsat-derived publisher-dataset

Description

This product provides statistical tools to exploit the time series of Landsat 7 data available in Digital Earth Australia, providing annual images of general conditions and how much an area changes for a given year.

The geomedian 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 which provides a "second order" high dimensional statistical composite for 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.

For more information, please see the DEA Geometric Median and Median Absolute Deviation Landsat

This product is part of the Digital Earth Australia Program

Bands

Resolution
25 meters

Bands

Name	Min	Max	Wavelength	Description
blue	0*	10000*	0.450-0.515 μm	Band blue surface reflectance geometric median.
green	0*	10000*	0.525-0.605 μm	Band green surface reflectance geometric median.
red	0*	10000*	0.630-0.690 μm	Band red surface reflectance geometric median.
near_infrared	0*	10000*	0.775-0.900 μm	Band near infrared surface reflectance geometric median.
shortwave_infrared_1	0*	10000*	1.550-1.750 μm	Band shortwave infrared 1 surface reflectance geometric median.
shortwave_infrared_2	0*	10000*	2.080-2.350 μm	Band shortwave infrared 2 surface reflectance geometric median.
Euclidean_distance_median_absolute_deviation	0*	10000*		The Median Absolute Deviation using Euclidean distance (EMAD). EMAD is more sensitive to changes in target brightness.
spectral_distance_median_absolute_deviation	0*	10000*		The Median Absolute Deviation using Cosine (spectral) distance (SMAD). SMAD is more sensitive to change in target spectral response.
Bray_Curtis_dissimilarity_median_absolute_deviation	0*	10000*		The Median Absolute Deviation using Bray Curtis dissimilarity (BCMAD). BCMAD is more sensitive to the distribution of the observation values through time.
count	0*	400*		The number of the available pixels used for calculation per calendar year.

* estimated min or max value

Terms of Use

Terms of Use

CC-BY-4.0

Citations

Citations:

• Roberts, D., Mueller, N., & Mcintyre, A. (2017). High-dimensional pixel composites from earth observation time series. IEEE Transactions on Geoscience and Remote Sensing, 55(11), 6254-6264. doi:10.1109/TGRS.2017.2723896. Roberts, D., Dunn, B., & Mueller, N. (2018). Open data cube products using high-dimensional statistics of time series. IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 8647-8650. doi:10.1109/IGARSS.2018.8518312.

DOIs

• https://doi.org/10.1109/IGARSS.2018.8518312
• https://doi.org/10.1109/TGRS.2017.2723896

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Code Editor (JavaScript)

var geomedian_ls7 = ee.ImageCollection('projects/geoscience-aus-cat/assets/ga_ls7e_nbart_gm_cyear_3');

var geometry = 
    /* color: #98ff00 */
    /* displayProperties: [
      {
        "type": "rectangle"
      }
    ] */
    ee.Geometry.Polygon(
      [[[121.15880998755823, -15.010654451073695],
        [121.15880998755823, -18.377531570740548],
        [125.81701311255823, -18.377531570740548],
        [125.81701311255823, -15.010654451073695]]], null, false);
          
var composite = geomedian_ls7.filterBounds(geometry)
                             .filterDate('2008-01-01', '2009-01-01')
                             .mosaic();
                             
var visualization = {
  bands: ['red', 'green', 'blue'],
  min: 0,
  max: 3000
};

Map.centerObject(geometry, 10);
Map.addLayer(composite, visualization, '2008 True Color Composite');

Open in Code Editor

DEA Geometric Median and Median Absolute Deviation - Landsat 7 3.1.0

This product provides statistical tools to exploit the time series of Landsat 7 data available in Digital Earth Australia, providing annual images of general conditions and how much an area changes for a given year. The geomedian part of the product provides an "average" cloud-free image over the given year. …

projects/geoscience-aus-cat/assets/ga_ls7e_nbart_gm_cyear_3, australia,ga,geoscience-aus-cat,landsat-derived,publisher-dataset

2000-01-01T00:00:00Z/2021-01-01T00:00:00Z

-44.41 108.81 -9.13 157.82

Google Earth Engine

https://developers.google.com/earth-engine/datasets

• https://doi.org/10.1109/TGRS.2017.2723896
• https://doi.org/10.1109/TGRS.2017.2723896
• https://doi.org/10.1109/TGRS.2017.2723896