Search

Chinese Sign Language (CSL) offers the main means of communication for the hearing impaired in China. Sign Language Recognition (SLR) can shorten the distance between the hearing-impaired and healthy people and help them integrate into the society. Therefore, SLR has become the focus of sign language application research. Over the years, the continuous development of new technologies provides a source and motivation for SLR. This paper aims to cover the most recent approaches in Chinese Sign Language Recognition (CSLR). With a thorough review of superior methods from 2000 to 2019 in CSLR researches, various techniques and algorithms such as scale-invariant feature transform, histogram of oriented gradients, wavelet entropy, Hu moment invariant, Fourier descriptor, gray-level co-occurrence matrix, dynamic time warping, principal component analysis, autoencoder, hidden Markov model (HMM), support vector machine (SVM), random forest, skin color modeling method, k-NN, artificial neural network, convolutional neural network (CNN), and transfer learning are discussed in detail, which are based on several major stages, that is, data acquisition, preprocessing, feature extraction, and classification. CSLR was summarized from some aspect as follows: methods of classification and feature extraction, accuracy/performance evaluation, and sample size/datasets. The advantages and limitations of different CSLR approaches were compared. It was found that data acquisition is mainly through Kinect and camera, and the feature extraction focuses on hand's shape and spatiotemporal factors, but ignoring facial expressions. HMM and SVM are used most in the classification. CNN is becoming more and more popular, and a deep neural network-based recognition approach will be the future trend. However, due to the complexity of the contemporary Chinese language, CSLR generally has a lower accuracy than other SLR. It is necessary to establish an appropriate dataset to conduct comparable experiments. The issue of decreasing accuracy as the dataset increases needs to resolve. Overall, our study is hoped to give a comprehensive presentation for those people who are interested in CSLR and SLR and to further contribute to the future research. [ABSTRACT FROM AUTHOR]

The dual-polarized Sentinel-1 synthetic aperture radar (SAR), which performs C-band SAR imaging day and night regardless of the weather, offers new opportunities for wetland cover monitoring in regions frequently covered by cloud. In this study, a decision tree (DT) classifier was applied to investigate the utility of Sentinel-1 for wetland classification in Poyang Lake, China. Six land cover classes were identified: water body, bare land, aquatic vegetation, cropland, forest, and urban area surrounding the lake. Two types of features were extracted from the dual-polarized SAR data, namely, the backscattering coefficients and the polarimetric decomposition components. Then, the DT classifier was trained and applied with backscattering features, polarimetric features, or a combination of the two features. The overall accuracy of all the classifiers was over 90% for the different feature combinations (98.02, 90.63, and 98.59%) for the classes in the lake area, compared with less than 78% (74.84, 63.01, and 77.29%) when the classes surrounding the lake were also considered, which demonstrates the potential of Sentinel-1 SAR data for wetland monitoring. The accuracy of different feature combinations increased in the following order: polarimetric features < backscattering features < combination of polarimetric and backscattering features. The artificial neural network, naïve Bayes, random forest, and adaptive boost algorithms were compared for the case of using backscattering features, and the adaptive boost algorithm showed lower performance than the other three algorithms. [ABSTRACT FROM AUTHOR]

• CNNs are considered for dealing with the flood susceptibility mapping task. • Two different CNN frameworks of classification and feature extraction are presented. • Three data presentation forms are designed for the proposed CNN frameworks. • Reliable flood susceptibility maps can be obtained by using the proposed CNNs. • Prediction performance of SVM can be improved using the CNNs for feature extraction. Flood is a very destructive natural disaster in the world, which seriously threatens the safety of human life and property. In this paper, the most popular convolutional neural network (CNN) is introduced to assess flood susceptibility in Shangyou County, China. The main contributions of this study are summarized as follows. First, the CNN technique is used for flood susceptibility mapping through two different CNN classification and feature extraction frameworks. Second, three data presentation methods are designed in the CNN architecture to fit the two proposed frameworks. To construct the proposed CNN-based methods, 13 flood triggering factors related to historical flood events in the study area were prepared. The performance of these CNN-based methods was evaluated using several objective criteria in comparison to the conventional support vector machine (SVM) classifier. Experiments results demonstrate that all the CNN-based methods can produce more reliable and practical flood susceptibility maps. For example, the proposed CNN-based classifiers were 0.022–0.054 higher than SVM in terms of area under the curve (AUC). In addition, in the classification process, CNN-based feature extraction can effectively improve the prediction capability of SVM by 0.021–0.051 in terms of AUC. Therefore, the proposed CNN frameworks can help mitigate and manage floods. [ABSTRACT FROM AUTHOR]