text
stringlengths 0
820
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(ETM+)Landsat 6 |
(ETM)Landsat 4–5 |
(TM)Landsat 1–5 |
(MSS)Landsat 3 |
(RBV)Landsat 1–2 |
(RBV) |
89 |
7 65 4 |
32187 5 432187 5 43217 5 432143211321 |
11 121530100153060153012030120804080 |
Resolution (m) |
11 10666 |
Figure 6: Spectral wavelengths and spatial resolutions of each band captured by all Landsat sensors. |
On Landsats 1–3, MSS bands were actually numbered 4–7. Landsat 9 introduced new and improved |
OLI-2/TIRS-2 sensors, but the bands are identical, so the sensors were combined in this figure. |
A.7 Data visualization |
(a) Spring (2021-03-22) |
(b) Summer (2022-06-13) |
(c) Fall (2022-10-19) |
(d) Winter (2022-12-22) |
Figure 7: Example location showing the time-series nature of SSL4EO-L. Each location has imagery |
from 4 different seasons. Images are selected from a 60-day window centered about the vernal and |
autumnal equinoxes and the summer and winter solstices in order to maximize seasonal changes. |
Images are limited to a 2-year window to minimize man-made changes. Image location is Ci County, |
Handan, Heibei, China. |
20 |
A.8 Model complexity |
Table 6: Complexity of backbone models used in this paper. Includes the number of parameters, |
memory requirements, floating point operations per second (FLOPS), and multiply-accumulate op- |
erations (MACs) of each model. All experiments were performed on an NVIDIA A100 GPU. |
Model # Params (M) Memory (MB) FLOPS (G/s) MACs (G) |
ResNet-18 11.21 44.87 622.49 136.21 |
ResNet-50 23.56 94.46 366.32 281.72 |
ViT-S16 22.46 89.83 423.61 281.28 |
A.9 Sampling algorithm |
Procedure DownloadSSL4EO( N= 250 ,000, S= 4, σ= 50 km) |
Data: M={µ}centroids of 10K most populous cities in the world |
Result: Downloads non-overlapping, cloud-free, nodata-free images from Nlocations during |
Sseasons |
X← {} |
while len( X)< N : |
µ∼ U(M) |
x∼ N(µ, σ) |
# Ensure x does not overlap with existing sampled patches |
ifOverlaps (x,X):# 264 px buffer |
continue |
# Look for S cloud-free, nodata-free images at location x |
T← {} |
t←0 |
fortinrange( S):# 60-day and 2-year window around equinoxes/solstices |
ifCloudCover( x, t):# 20% threshold |
continue |
ifNoData( x, t): |
continue |
T←T∪ {t} |
iflen( T)< S: |
continue |
# Download from Google Earth Engine |
Download( x,T) |
X←X∪ {x} |
21 |
Detecting trend and seasonal changes in satellite image time series |
Jan Verbesselta,⁎, Rob Hyndmanb, Glenn Newnhama, Darius Culvenora |
aRemote Sensing Team, CSIRO Sustainable Ecosystems, Private Bag 10, Melbourne VIC 3169, Australia |
bDepartment of Econometrics and Business Statistics, Monash University, Melbourne VIC 3800, Australia |
abstract article info |
Article history: |
Received 24 June 2009Received in revised form 13 August 2009Accepted 18 August 2009 |
Keywords:Change detectionNDVI |
Time series |
Trend analysisMODISPiecewise linear regressionVegetation dynamicsPhenologyA wealth of remotely sensed image time series covering large areas is now available to the earth science |
community. Change detection methods are often not capable of detecting land cover changes within time |
series that are heavily in fluenced by seasonal climatic variations. Detecting change within the trend and |
seasonal components of time series enables the classi fication of different types of changes. Changes occurring |
in the trend component often indicate disturbances (e.g. fires, insect attacks), while changes occurring in the |
seasonal component indicate phenological changes (e.g. change in land cover type). A generic changedetection approach is proposed for time series by detecting and characterizing Breaks For Additive Seasonal |
and Trend (BFAST). BFAST integrates the decomposition of time series into trend, seasonal, and remainder |
components with methods for detecting change within time series. BFAST iteratively estimates the time andnumber of changes, and characterizes change by its magnitude and direction. We tested BFAST by simulating16-day Normalized Difference Vegetation Index (NDVI) time series with varying amounts of seasonality and |
noise, and by adding abrupt changes at different times and magnitudes. This revealed that BFAST can |
robustly detect change with different magnitudes (>0.1 NDVI) within time series with different noise levels(0.01 –0.07σ) and seasonal amplitudes (0.1 –0.5 NDVI). Additionally, BFAST was applied to 16-day NDVI |
Moderate Resolution Imaging Spectroradiometer (MODIS) composites for a forested study area in south |
eastern Australia. This showed that BFAST is able to detect and characterize spatial and temporal changes in aforested landscape. BFAST is not speci fic to a particular data type and can be applied to time series without |
the need to normalize for land cover types, select a reference period, or change trajectory. The method can be |
integrated within monitoring frameworks and used as an alarm system to flag when and where changes |
occur. |
Crown Copyright © 2009 Published by Elsevier Inc. All rights reserved. |
1. Introduction |
Natural resource managers, policy makers and researchers de- |
mand knowledge of land cover changes over increasingly large spatial |
and temporal extents for addressing many pressing issues such as |
global climate change, carbon budgets, and biodiversity ( DeFries et al., |
1999; Dixon et al., 1994 ). Detecting and characterizing change over |
time is the natural first step toward identifying the driver of the |
change and understanding the change mechanism. Satellite remote |
sensing has long been used as a means of detecting and classifying |
changes in the condition of the land surface over time ( Coppin et al., |
2004; Lu et al., 2004 ). Satellite sensors are well-suited to this task |
because they provide consistent and repeatable measurements at a |
spatial scale which is appropriate for capturing the effects of many |
processes that cause change, including natural (e.g. fires, insect |