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Presented by Dino Ienco, Researcher @Irstea (UMR-TETIS) at the Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
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DETECTING SPATIOTEMPORAL DYNAMICS IN SATELLITE REMOTE SENSING TIME SERIES: METHODOLOGICAL APPROACH COMBINING OBIA AND DATA MINING TECHNIQUES
Dino Ienco
dino.ienco@irstea.fr
Researcher @Irstea (UMR-TETIS)
Fabio N. Güttler
Jordi Nin,
Pascal Poncelet,
Maguelonne Teisseire
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
I. Climate Change & Remote Sensing
II. Introduction
III. Study Area
IV. Methods
V. Results
VI. Conclusions / Perspectives
OUTLINE
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
I. CLIMATE CHANGES & REMOTE SENSING
Climate changes :
• Important Issue at global/local scale
• Impacts on various sectors: agriculture, fishery,
forestry, water management, health, coastal
environment, natural habitats, etc…
Study what happens in the past to
understand how to act in the future
Remote Sensing analysis constitutes an important tool to
study what happens:
- Capture area characterisitcs (spectral/radiometric)
- Huge quantity of images available soon
- Acquisition of time series over the same area
I. CLIMATE CHANGES & REMOTE SENSING
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
Series of satellite images can help to understand long term behaviors
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
I. CLIMATE CHANGES & REMOTE SENSING
Mining series of satellite images can help to:
Automatically analyse huge data
Study long term behaviour
Extract evolutions of natural/artificial habitats
Methodology to Mine Evolutions/Changes on
Remote Sensing time series data
II. INTRODUCTION
• Spectral response of natural vegetation
• Vegetation types
• Textural response
• Vegetation structure (mapping physiognomic
classes, e.g. shrubland and grassland)
• Temporal response
• Vegetation phenology
and dynamics
MOTIVATIONS – REMOTE SENSING POSSIBILITIES
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
II. INTRODUCTION
• Detect spatiotemporal evolutions on satellite time series automatically
• Provided useful information for natural habitats monitoring and mapping
• Propose a new and adapted method for future high repetitivity RS time series
(i.e. Sentinel-2) that can be employed to understand Climate Changes
OBJECTIVES
Methods describing multi-temporal behaviour are among open
challenges in OBIA (Blaschke et al. 2014 ; Chen et al. 2012)
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
[Blaschke et al 2014] Blaschke et al. Geographic object-based image analysis towards a new paradigm. ISPRS Journal of
Photogrammetry and Remote Sensing 87 (0), 180–191.
[Chen et al. 2012] Chen, G., Hay, G. J., Carvalho, L. M. T., Wulder, M. A., 2012. Object- based change detection.
International Journal of Remote Sensing 33 (14), 4434–4457.
III. STUDY AREAS AND TIME SERIES
Low Aude Valley
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
Area: 4,842 ha
Dominated by
natural habitat
types of
Community
interest (19 in
total)
III. STUDY AREAS AND TIME SERIES
Low Aude Valley
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
MOTIVATIONS
- Approach coupling OBIA (Object-based Image
Analysis) and Data Mining
- Method ables to track object evolution along the time
- Main assumption - Maximal Spatial Extent: For each complex habitat there will be a
timestamp, in the time series, in which we can
observe its maximum extent
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
GENERAL SCHEMA
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
MAIN STEPS
Step 1 •Preprocessing
Step 2
Step 3
Step 4
Step 5
Step 6
- data standardization
- fine geometrical registration
- spatial subset
- spectral indices
- …
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
Step 1 •Preprocessing
Step 2 •Segmentation
Step 3
Step 4
Step 5
Step 6
T0
T1
Tn
…
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
MAIN STEPS
Step 1 •Preprocessing
Step 2 •Segmentation
Step 3 •BB selection
Step 4
Step 5
Step 6
- Retrieve the Maximal Spatial Extents - On the whole study area
- Through the 6 timestamp
- The output is a list of objects
candidateBB
T0
T1
Tn
…
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
MAIN STEPS
Step 1 •Preprocessing
Step 2 •Segmentation
Step 3 •BB selection
Step 4
Step 5
Step 6
- Filtering of candidateBB - Obtain a global cover of the
study area
- Decrease the overlapping
among the BB (redundancy)
- Retrieve the Maximal Spatial Extents - On the whole study area
- Through the 6 timestamp
- The output is a list of objects
candidateBB
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
MAIN STEPS
Step 1 •Preprocessing
Step 2 •Segmentation
Step 3 •BB selection
Step 4 •Graph construction
Step 5
Step 6
- Each BB is exploited to build an
evolution graph
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
MAIN STEPS
Step 1 •Preprocessing
Step 2 •Segmentation
Step 3 •BB selection
Step 4 •Graph construction
Step 5
Step 6
T0
T1
T2
T3
T4
object ID
timestamp
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
MAIN STEPS
Step 1 •Preprocessing
Step 2 •Segmentation
Step 3 •BB selection
Step 4 •Graph construction
Step 5
Step 6
T0
T1
T2
T3
T4
object ID
timestamp
overlap between objects
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
MAIN STEPS
Step 1 •Preprocessing
Step 2 •Segmentation
Step 3 •BB selection
Step 4 •Graph construction
Step 5
•Measuring evolutions and similarity
- Evaluate the temporal evolution of a
natural habitat
- Evaluate the global intensity of
evolution of a graph
- graph ranking for each set of
chosen attributes
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
IV. PROPOSED METHODOLOGY
MAIN STEPS
V. RESULTS
- Total Number of Objects)
3 373 (~ 562 per timestamp)
- Total Number of generated graphs
BPA = 340
Landsat 2009
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
- Each node contains a set of
attributes
- Band1
- Band2
- …
- NDVI
- NDWI
- VSDI
- …
- The graphs are also described
by some features
- N. of nodes
- N. of edges
- N. of sequences
- … Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
V. RESULTS
EVOLUTION GRAPHS
EVOLUTION GRAPHS
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
V. RESULTS
INTENSITY OF EVOLUTION
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
V. RESULTS
VI. CONCLUSIONS
• The proposed methodology :
• Connects objects along the time series monitoring the same phenomenon over time
• Combines OBIA & Data Mining to extract spatiotemporal evolutions
• Can be easily applied to longer time series, no assumption on the number of images is made
• Can be used to generate a ranking of the habitats considering their changes during the time (and the
ranking can be exploited by expert to focus their attention on particular portion of the study area)
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
Tri-National Scientific Workshop, 29 October 2015, Bogor, Indonesia
Thank you for your attention
ANY QUESTION
NDVI and NDWI evolutions
22-Feb
NDVI and NDWI evolutions
27-Feb
NDVI and NDWI evolutions
03-Apr
NDVI and NDWI evolutions
13-Apr
NDVI and NDWI evolutions
18-Apr
NDVI and NDWI evolutions
23-Apr
NDVI and NDWI evolutions
13-May
NDVI and NDWI evolutions
02-Jun
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