Machine Learning For Detecting Anomalies In SAR Data
- Slides: 16
Machine Learning For Detecting Anomalies In SAR Data Yuval Haitman Itay Berkovich Supervisor: Prof. Stanley Rotman 1
Outline • Introduction • SAR temporal data • Algorithm implementation • Results and validation • Conclusion • Questions 2
Introduction • Research Domain: anomaly detection in remote sensing multi-dimensional imagery • What will be defined as an anomaly? • Difficulties of anomaly detectors: • • Choosing a proper decision threshold • Dealing with noise Our goal: develop an algorithm for anomaly detection that will use data adaptive thresholds and will be less affected by noise 3
SAR Data 4
RX Anomaly Detector • Common anomaly detector for multi-dimensional data • Assumption: • Image background follows multivariate normal distribution • Variations: • Global RX (GRX) • Local RX (LRX) 5
Non-Negative Matrix Factorization (NNMF) Sparse NNMF: 6
Non-Negative Matrix Factorization (NNMF) • The extracted features are trends in data • Each endmembers has unique time signature • The data is spanned using those trends 7
Non-Negative Matrix Factorization (NNMF) Original Data Reduced Data 8
Algorithm Overview 9
Preprocessing 10
Dimension Reduction and RX Detector 12
Thresholding method 13
Results and Validation • We used Google Earth for result validation • Figure (a) – SAR image with marked anomalies • Figure (b)- marked clusters on Google Earth image (a) (b) 14
Palmachim Set – Result Validation Shafdan pools (Red cluster) 17/10/11 29/01/12 Yes Planet –Rishon lesion (Yellow cluster) 11/02/10 30/03/11 17/10/11
Results and Validation – Extended cluster 16
Conclusions • We have implemented a new algorithm that is able to detect anomalies which other algorithms could not • The algorithm should be tested on more data sets in order to explore it’s reliability and sensitivity of detection 18
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