Orthogonal Subspace Projection (OSP) has been shown a successful technique for hyperspectral image analysis. It requires a linear mixture model with complete target knowledge to per-form subpixel detection and mixed c...
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ISBN:
(纸本)0819444758
Orthogonal Subspace Projection (OSP) has been shown a successful technique for hyperspectral image analysis. It requires a linear mixture model with complete target knowledge to per-form subpixel detection and mixed classification. Constrained energy minimization (CEM) has been also shown to be effective in subpixel detection and mixed pixel classification which only needs the knowledge of targets of interest. rx-algorithm which has been widely used for anomaly detection in signal processing does not require any prior target information. Interestingly, these three techniques are closely related from an aspect of information being used in these three techniques. They all perform some sort of matched filter with different levels of information used in the filter. This paper investigates and explores their relationship that sheds light on their algorithm design.
We present a TensorFlow implementation of the rx-algorithm for anomaly detection in multi-spectral and hyperspectral imagery. In this paper, we perform a runtime performance comparison of the algorithm, implemented us...
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ISBN:
(纸本)9781510666955;9781510666962
We present a TensorFlow implementation of the rx-algorithm for anomaly detection in multi-spectral and hyperspectral imagery. In this paper, we perform a runtime performance comparison of the algorithm, implemented using: NumPy, SciPy and TensorFlow libraries on a CPU, a GPU (where applicable) as well as on edge hardware (Jetson TX2). The rx detection algorithm makes use of either local or global background statistics, such as the mean and covariance, to find anomalous pixels. In the approach examined here, the statistics are estimated using local background samples from the area neighbouring the pixel under test. Such algorithms are typically implemented in Python using the NumPy library for numerical operations;however, a preliminary literature review found no formal investigations have been made into the suitability of alternative frameworks to optimise the performance on edge hardware. Our TensorFlow (and SciPy) implementations involve the use of a convolutional operations to calculate the required statistics. The use of these libraries significantly reduces the algorithm's run time. We evaluate the implementation using a range of hardware, in order to get a diverse set of results and to highlight the differences in run times on each. We also show a comparative set of implementations of a Matched Filter algorithm for target detection. This algorithm uses a very similar approach to the rxalgorithm, but is provided with a template target spectrum to detect within the image. Notable improvements (similar to 98% reduction in run time) in performance can be seen through the use of a TensorFlow implementation on GPU. Results are demonstrated by trialing on multispectral imagery for ship detection.
A common anomaly detection algorithm for hyperspectral imagery is the rxalgorithm based on the Mahalanobis distance of each pixel from the image mean. This is a benchmark algorithm which can be applied either directl...
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ISBN:
(数字)9781510635623
ISBN:
(纸本)9781510635623
A common anomaly detection algorithm for hyperspectral imagery is the rxalgorithm based on the Mahalanobis distance of each pixel from the image mean. This is a benchmark algorithm which can be applied either directly on a hyperspectral image or on a dimensionality-reduced hyperspectral image. Recent work on Non-Negative Matrix Factorization (NNMF) provides a fast-iterative algorithm for decomposing a hyperspectral cube and achieving dimensionality reduction. In this paper, we study the implementation of the NNMF algorithm on a hyperspectral data cube and propose two new anomaly detection algorithms, based on combining the NNMF and the rxalgorithms. In the first version, we apply the NNMF algorithm on a hyperspectral image reducing the dimensionality;we then apply the rxalgorithm. In the second version, we segment and cluster the dataset after applying the NNMF algorithm. Anomaly detection is then performed on this dataset. Using either of these algorithms overcomes a weakness of the rxalgorithm in handling background clusters which are close to each other. The algorithm was tested on the RIT blind test dataset. From our results, we conclude that the two versions of the algorithm are sensitive to different types of anomalies;a two-dimensional scatterplot of the data comparing the rx values to either of the NNMF algorithms enables us to distinguish between the anomaly types. The ground truth shows that we have achieved high accuracy and less false alarms.
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