text
stringlengths 0
820
|
---|
(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
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.