Ailong Ma

An Adaptive Memetic Fuzzy Clustering Algorithm With Spatial Information for Remote Sensing Imagery

Due to its inherent complexity, remote sensing image clustering is a challenging task. Recently, some spatial-based clustering approaches have been proposed; however, one crucial factor with regard to their clustering quality is that there is usually one parameter that controls their spatial information weight, which is difficult to determine. Meanwhile, the traditional optimization methods of the objective functions for these clustering approaches often cannot function well because they cannot simultaneously possess both a local search capability and a global search capability. Furthermore, these methods only use a single optimization method rather than hybridizing and combining the existing algorithmic structures. In this paper, an adaptive fuzzy clustering algorithm with spatial information for remote sensing imagery (AFCM_S1) is proposed, which defines a new objective function with an adaptive spatial information weight by using the concept of entropy. In order to further enhance the capability of the optimization, an adaptive memetic fuzzy clustering algorithm with spatial information for remote sensing imagery (AMASFC) is also proposed. In AMASFC, the clustering problem is transformed into an optimization problem. A memetic algorithm is then utilized to optimize the proposed objective function, combining the global search ability of a differential evolution algorithm with a local search method using Gaussian local search (GLS). The optimal value of the specific parameter in GLS, which determines the local search efficiency, can be obtained by comparing the objective function increment for different values of the parameter. The experimental results using three remote sensing images show that the two proposed algorithms are effective when compared with the traditional clustering algorithms.

Adaptive Multiobjective Memetic Fuzzy Clustering Algorithm for Remote Sensing Imagery

Due to the intrinsic complexity of remote sensing images and the lack of prior knowledge, clustering for remote sensing images has always been one of the most challenging tasks in remote sensing image processing. Recently, clustering methods for remote sensing images have often been transformed into multiobjective optimization problems, making them more suitable for complex remote sensing image clustering. However, the performance of the multiobjective clustering methods is often influenced by their optimization capability. To resolve this problem, this paper proposes an adaptive multiobjective memetic fuzzy clustering algorithm (AFCMOMA) for remote sensing imagery. In AFCMOMA, a multiobjective memetic clustering framework is devised to optimize the two objective functions, i.e., Jm and the Xie-Beni (XB) index. One challenging task for memetic algorithms is how to balance the local and global search capabilities. In AFCMOMA, an adaptive strategy is used, which can adaptively achieve a balance between them, based on the statistical characteristic of the objective function values. In addition, in the multiobjective memetic framework, in order to acquire more individuals with high quality, a new population update strategy is devised, in which the updated population is composed of individuals generated in both the local and global searches. Finally, to evaluate the proposed AFCMOMA algorithm, experiments using three remote sensing images were conducted, which confirmed the effectiveness of the proposed algorithm.

Computational intelligence in optical remote sensing image processing

Abstract With the ongoing development of Earth observation techniques, huge amounts of remote sensing images with a high spectral-spatial-temporal resolution are now available, and have been successfully applied in a variety of fields. In the process, they bring about great challenges, such as high-dimensional datasets (the high spatial resolution and hyperspectral features), complex data structures (nonlinear and overlapping distributions), and the nonlinear optimization problem (high computational complexity). Computational intelligence techniques, which are inspired by biological systems, can provide possible solutions to the above-mentioned problems. In this paper, we provide an overview of the application of computational intelligence technologies in optical remote sensing image processing, including: 1) feature representation and selection; 2) classification and clustering; and 3) change detection. Subsequently, the core potentials of computational intelligence for optical remote sensing image processing are delineated and discussed.

Semisupervised Subspace-Based DNA Encoding and Matching Classifier for Hyperspectral Remote Sensing Imagery

Hyperspectral remote sensing images, which are characterized by their high dimensionality, provide us with the capability to accurately identify objects on the ground. They can also be used to identify subclasses of objects. However, these subclasses are usually embedded in different subspaces due to the complex distribution of pixels in the feature space. In the literature, few hyperspectral image classification methods can take both the subclass and subspace into consideration at the same time. Motivated by the fact that natural DNA can distinguish biological subspecies (subclasses in hyperspectral images) using critical DNA fragments (subspaces in hyperspectral images), a semisupervised subspace-based DNA encoding and matching classifier for hyperspectral remote sensing imagery (SSDNA) is proposed in this paper. First, in the process of DNA encoding, the hyperspectral remote sensing image is transformed into a DNA cube, in which the first-order spectral curve of the hyperspectral remote sensing image is utilized in order to take the gradient information of the spectral curve into consideration. Second, in the process of DNA optimization, evolutionary algorithms are used to obtain the best DNA library of the typical objects, which includes the following: 1) A multicenter individual representation is designed in order to consider the existence of subclasses in the hyperspectral remote sensing image; 2) the unlabeled samples are utilized in the process of population initialization and fitness calculation to enhance the diversity of the population and the generalization of the classification performance; and 3) the different classes are embedded in different subspaces. A semisupervised technique is used to extract the subspaces, including the global subspace for all the classes and the local subspace for each class. Three hyperspectral data sets were tested and confirm that SSDNA performs better than the other supervised or semisupervised classifiers.

Spectral-Spatial Clustering with a Local Weight Parameter Determination Method for Remote Sensing Imagery

Remote sensing image clustering is a challenging task considering its intrinsic complexity. Recently, by combining the spectral and spatial information of the remote sensing data, the clustering performance can be dramatically enhanced, termed as Spectral-Spatial Clustering (SSC). However, it has always been difficult to determine the weight parameter for balancing the spectral term and spatial term of the clustering objective function. In this paper, spectral-spatial clustering with a local weight parameter determination method for remote sensing image was proposed, i.e., L-SSC. In L-SSC, considering the large scale of remote sensing images, the weight parameter can be determined locally in a patch image instead of the whole image. Afterwards, the local weight parameter was used in constructing the objective function of L-SSC. Thus, the remote sensing image clustering problem was transformed into an optimization problem. Finally, in order to achieve a better optimization performance, a variant of differential evolution (i.e., jDE) was used as the optimizer due to its powerful optimization capability. Experimental results on three remote sensing images, including a Wuhan TM image, a Fancun Quickbird image, and an Indian Pine AVIRIS image, demonstrated that the proposed L-SSC can acquire higher clustering accuracy in comparison to other spectral-spatial clustering methods.

Optimal Decision Fusion for Urban Land-Use/Land-Cover Classification Based on Adaptive Differential Evolution Using Hyperspectral and LiDAR Data

Hyperspectral images and light detection and ranging (LiDAR) data have, respectively, the high spectral resolution and accurate elevation information required for urban land-use/land-cover (LULC) classification. To combine the respective advantages of hyperspectral and LiDAR data, this paper proposes an optimal decision fusion method based on adaptive differential evolution, namely ODF-ADE, for urban LULC classification. In the ODF-ADE framework the normalized difference vegetation index (NDVI), gray-level co-occurrence matrix (GLCM) and digital surface model (DSM) are extracted to form the feature map. The three different classifiers of the maximum likelihood classifier (MLC), support vector machine (SVM) and multinomial logistic regression (MLR) are used to classify the extracted features. To find the optimal weights for the different classification maps, weighted voting is used to obtain the classification result and the weights of each classification map are optimized by the differential evolution algorithm which uses a self-adaptive strategy to obtain the parameter adaptively. The final classification map is obtained after post-processing based on conditional random fields (CRF). The experimental results confirm that the proposed algorithm is very effective in urban LULC classification.

A Spatial Gaussian Mixture Model for Optical Remote Sensing Image Clustering

Clustering has always been one of the most challenging tasks in optical remote-sensing image (ORSI) processing, as a result of the intrinsic complexity of the distribution of the ground objects. The Gaussian mixture model (GMM), as a traditional, effective clustering method, has been widely applied. However, the traditional model does not take the spatial information into consideration. To solve the problem, a new model named the spatial Gaussian mixture model (SGMM) is proposed for ORSI clustering. The SGMM can incorporate the spatial information by generating spatial windows around pixels. An estimation algorithm based on expectation-maximization (EM) is also developed to estimate the parameters of the SGMM. The relationships between the SGMM/GMM and the SGMM/probabilistic latent semantic analysis (PLSA) are analyzed theoretically. The proposed SGMM can be considered to be an extension of the GMM and a continuous version of PLSA. In addition, two methods based on the SGMM are proposed to infer the cluster labels of the pixels. One method is based on the maximum likelihood rule, and is called SGMM-MLR, while the other method combines the SGMM and conditional random fields (CRF), and is called SGMM-CRF. The experimental results with three remote-sensing images show that the proposed clustering method based on the SGMM can improve the performance of clustering for ORSIs, compared to k-means, fuzzy c-means (FCM), and the GMM. It is also able to acquire a better performance than the latest cluster methods with spatial information, such as kernel weighted fuzzy local information c-means (KWFLICM), and the GMM coupled with CRF.

Adaptive Differential Evolution Fuzzy Clustering Algorithm with Spatial Information and Kernel Metric for Remote Sensing Imagery

In this paper, an adaptive differential evolution fuzzy clustering algorithm with spatial information and kernel metric for remote sensing imagery, namely KADESFC, is proposed. In KADESFC, the clustering problem is transformed into an optimization problem, which minimizes a proposed kernelized objective function with an adaptive spatial constraint term. Differential evolution algorithm is utilized to optimize the kernelized objective function, which uses several differential evolution operators. Experimental results on two remote sensing images show that the proposed algorithm is promising compared with several traditional clustering algorithms.

Spectral-spatial DNA encoding discriminative classifier for hyperspectral remote sensing imagery

Hyperspectral remote sensing image classification is one of the most challenging tasks. In our previous work, motivated by the similarity between the structures of DNA and hyperspectral remote sensing images, a DNA matching mechanism was used to transform the hyperspectral remote sensing image into a DNA cube for classification. However, the above DNA encoding strategy lacks the process of encoding accurate spectral and spatial feature into the DNA cube, resulting in unsatisfying classification performance. In this paper, a spectral-spatial DNA encoding strategy for encoding accurate spectral and spatial feature of hyperspectral remote sensing image is proposed. In the spectral dimension, the first-order spectral curve is encoded into the DNA cube, while in the spatial dimension, the principal components or their corresponding texture feature (GLCM) are encoded into the DNA cube. Finally, different with the previous DNA encoding classifier using genetic algorithm (GA), the paper combines the discriminative classifier (i.e. SVM) with spectral-spatial DNA encoding to improve classification performance for hyperspectral remote sensing imagery. The experimental results confirmed the effectiveness of the newly devised DNA encoding strategy and the discriminative classifier in classifying the DNA cube.

Change Detection Based on Multi-Feature Clustering Using Differential Evolution for Landsat Imagery

Change detection (CD) of natural land cover is important for environmental protection and to maintain an ecological balance. The Landsat series of satellites provide continuous observation of the Earth’s surface and is sensitive to reflection of water, soil and vegetation. It offers fine spatial resolutions (15–80 m) and short revisit times (16–18 days). Therefore, Landsat imagery is suitable for monitoring natural land cover changes. Clustering-based CD methods using evolutionary algorithms (EAs) can be applied to Landsat images to obtain optimal changed and unchanged clustering centers (clusters) with minimum clustering index. However, they directly analyze difference image (DI), which finds itself subject to interference by Gaussian noise and local brightness distortion in Landsat data, resulting in false alarms in detection results. In order to reduce image interferences and improve CD accuracy, we proposed an unsupervised CD method based on multi-feature clustering using the differential evolution algorithm (M-DECD) for Landsat Imagery. First, according to characteristics of Landsat data, a multi-feature space is constructed with three elements: Wiener de-noising, detail enhancement, and structural similarity. Then, a CD method based on differential evolution (DE) algorithm and fuzzy clustering is proposed to obtain global optimal clusters in the multi-feature space, and generate a binary change map (CM). In addition, the control parameters of the DE algorithm are adjusted to improve the robustness of M-DECD. The experimental results obtained with four Landsat datasets confirm the effectiveness of M-DECD. Compared with the results of conventional methods and the current state-of-the-art methods based on evolutionary clustering, the detection accuracies of the M-DECD on the Mexico dataset and the Sardinia dataset are very close to the best results. The accuracies of the M-DECD in the Alaska dataset and the large Canada dataset increased by about 3.3% and 11.9%, respectively. This indicates that multiple features are suitable for Landsat images and the DE algorithm is effective in searching for an optimal CD result.