scholarly journals Change Detection using Deep Learning and Machine Learning Techniques for Multispectral Satellite Images

Change detection is used to find whether the changes happened or not between two different time periods using remote sensing images. We can use various machine learning techniques and deep learning techniques for the change detection analysis using remote sensing images. This paper mainly focused on computational and performance analysis of both techniques in the application of change detection .For each approach, we considered ten different kinds of algorithms and evaluated the performance. Moreover, in this research work, we have analyzed merits and demerits of each method which have used to change detection.

2021 ◽  
Author(s):  
Milad Asgarimehr ◽  
Caroline Arnold ◽  
Felix Stiehler ◽  
Tobias Weigel ◽  
Chris Ruf ◽  
...  

<p>The Global Navigation Satellite System Reflectometry (GNSS-R) is a novel remote sensing technique exploiting GNSS signals after reflection off the Earth's surface. The capability of spaceborne GNSS-R to monitor ocean state and the surface wind is recently well demonstrated, which offers an unprecedented sampling rate and much robustness during rainfall. The Cyclone GNSS (CyGNSS) is the first spaceborne mission fully dedicated to GNSS-R, launched in December 2016.</p><p>Thanks to the low development costs of the GNSS-R satellite missions as well as the capability of tracking multiple reflected signals from numerous GNSS transmitters, the GNSS-R datasets are much bigger compared to those from conventional remote sensing techniques. The CyGNSS provides a high number of unique samples in the order of a few millions monthly.  Deep learning can therefore be implemented in GNSS-R even more efficiently than other remote sensing domains. With the upcoming GNSS-R CubeSats, the data volume is expected to increase in the near future and GNSS-R “Big data” can be a future challenge. Deep learning methods are additionally able to correct the potential effects, both technical and geophysical, dictated by data empirically when the mechanisms are not well described by the theoretical knowledge. This poses the question if GNSS-R should embrace deep learning and can benefit from this modern data scientific method like other Earth Observation domains.</p><p>The receivers onboard CyGNSS cross-correlate the reflected signals received at a nadir antenna to a locally generated replica. The cross-correlation power at a range of the signal delay and Doppler frequency shift is the observational output of the receivers being called delay-Doppler Maps (DDMs). The mapped power is inversely proportional to the ocean roughness and consequently surface winds.</p><p>Few recent studies innovatively show some merits of machine learning techniques for the derivations of ocean winds from the DDMs. However, the capability of machine learning techniques, especially deep learning for an operational data derivation needs to be better characterized. Normally, the operational retrieval algorithms are developed based on an existing dataset and are supposed to operate on the upcoming measurements. Therefore, machine learning-based models are supposed to generalize well on the unseen data in future periods. Herein, we aim at the characterization of deep learning capabilities for these GNSS-R operational purposes.</p><p>In this interdisciplinary study, we present a deep learning algorithm processing the CyGNSS measurements to derive wind speed data. The model is supposed to meet an acceptable level of generalization on the upcoming unseen data, and alternatively can be used as an operational processing algorithm. We propose a deep model based on convolutional and fully connected layers processing the DDMs besides ancillary input features. The model leads to the so-far best quality of global wind speed estimates using GNSS-R measurements with a general root mean square error of 1.3 m/s over unseen data in a time span different from that of the training data.</p>


2021 ◽  
Vol 13 (8) ◽  
pp. 1507
Author(s):  
Haibo Wang ◽  
Jianchao Qi ◽  
Yufei Lei ◽  
Jun Wu ◽  
Bo Li ◽  
...  

Automatic detection of newly constructed building areas (NCBAs) plays an important role in addressing issues of ecological environment monitoring, urban management, and urban planning. Compared with low-and-middle resolution remote sensing images, high-resolution remote sensing images are superior in spatial resolution and display of refined spatial details. Yet its problems of spectral heterogeneity and complexity have impeded research of change detection for high-resolution remote sensing images. As generalized machine learning (including deep learning) technologies proceed, the efficiency and accuracy of recognition for ground-object in remote sensing have been substantially improved, providing a new solution for change detection of high-resolution remote sensing images. To this end, this study proposes a refined NCBAs detection method consisting of four parts based on generalized machine learning: (1) pre-processing; (2) candidate NCBAs are obtained by means of bi-temporal building masks acquired by deep learning semantic segmentation, and then registered one by one; (3) rules and support vector machine (SVM) are jointly adopted for classification of NCBAs with high, medium and low confidence; and (4) the final vectors of NCBAs are obtained by post-processing. In addition, area-based and pixel-based methods are adopted for accuracy assessment. Firstly, the proposed method is applied to three groups of GF1 images covering the urban fringe areas of Jinan, whose experimental results are divided into three categories: high, high-medium, and high-medium-low confidence. The results show that NCBAs of high confidence share the highest F1 score and the best overall effect. Therefore, only NCBAs of high confidence are considered to be the final detection result by this method. Specifically, in NCBAs detection for three groups GF1 images in Jinan, the mean Recall of area-based and pixel-based assessment methods reach around 77% and 91%, respectively, the mean Pixel Accuracy (PA) 88% and 92%, and the mean F1 82% and 91%, confirming the effectiveness of this method on GF1. Similarly, the proposed method is applied to two groups of ZY302 images in Xi’an and Kunming. The scores of F1 for two groups of ZY302 images are also above 90% respectively, confirming the effectiveness of this method on ZY302. It can be concluded that adoption of area registration improves registration efficiency, and the joint use of prior rules and SVM classifier with probability features could avoid over and missing detection for NCBAs. In practical applications, this method is contributive to automatic NCBAs detection from high-resolution remote sensing images.


IEEE Access ◽  
2021 ◽  
Vol 9 ◽  
pp. 16988-16998
Author(s):  
Gabriel Villavicencio Arancibia ◽  
Osvaldo Pina Bustamante ◽  
Gabriel Hermosilla Vigneau ◽  
Hector Allende-Cid ◽  
Gonzalo Suazo Fuentelaba ◽  
...  

Vibration ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 341-356
Author(s):  
Jessada Sresakoolchai ◽  
Sakdirat Kaewunruen

Various techniques have been developed to detect railway defects. One of the popular techniques is machine learning. This unprecedented study applies deep learning, which is a branch of machine learning techniques, to detect and evaluate the severity of rail combined defects. The combined defects in the study are settlement and dipped joint. Features used to detect and evaluate the severity of combined defects are axle box accelerations simulated using a verified rolling stock dynamic behavior simulation called D-Track. A total of 1650 simulations are run to generate numerical data. Deep learning techniques used in the study are deep neural network (DNN), convolutional neural network (CNN), and recurrent neural network (RNN). Simulated data are used in two ways: simplified data and raw data. Simplified data are used to develop the DNN model, while raw data are used to develop the CNN and RNN model. For simplified data, features are extracted from raw data, which are the weight of rolling stock, the speed of rolling stock, and three peak and bottom accelerations from two wheels of rolling stock. In total, there are 14 features used as simplified data for developing the DNN model. For raw data, time-domain accelerations are used directly to develop the CNN and RNN models without processing and data extraction. Hyperparameter tuning is performed to ensure that the performance of each model is optimized. Grid search is used for performing hyperparameter tuning. To detect the combined defects, the study proposes two approaches. The first approach uses one model to detect settlement and dipped joint, and the second approach uses two models to detect settlement and dipped joint separately. The results show that the CNN models of both approaches provide the same accuracy of 99%, so one model is good enough to detect settlement and dipped joint. To evaluate the severity of the combined defects, the study applies classification and regression concepts. Classification is used to evaluate the severity by categorizing defects into light, medium, and severe classes, and regression is used to estimate the size of defects. From the study, the CNN model is suitable for evaluating dipped joint severity with an accuracy of 84% and mean absolute error (MAE) of 1.25 mm, and the RNN model is suitable for evaluating settlement severity with an accuracy of 99% and mean absolute error (MAE) of 1.58 mm.


The Intrusion is a major threat to unauthorized data or legal network using the legitimate user identity or any of the back doors and vulnerabilities in the network. IDS mechanisms are developed to detect the intrusions at various levels. The objective of the research work is to improve the Intrusion Detection System performance by applying machine learning techniques based on decision trees for detection and classification of attacks. The methodology adapted will process the datasets in three stages. The experimentation is conducted on KDDCUP99 data sets based on number of features. The Bayesian three modes are analyzed for different sized data sets based upon total number of attacks. The time consumed by the classifier to build the model is analyzed and the accuracy is done.


Author(s):  
V Umarani ◽  
A Julian ◽  
J Deepa

Sentiment analysis has gained a lot of attention from researchers in the last year because it has been widely applied to a variety of application domains such as business, government, education, sports, tourism, biomedicine, and telecommunication services. Sentiment analysis is an automated computational method for studying or evaluating sentiments, feelings, and emotions expressed as comments, feedbacks, or critiques. The sentiment analysis process can be automated using machine learning techniques, which analyses text patterns faster. The supervised machine learning technique is the most used mechanism for sentiment analysis. The proposed work discusses the flow of sentiment analysis process and investigates the common supervised machine learning techniques such as multinomial naive bayes, Bernoulli naive bayes, logistic regression, support vector machine, random forest, K-nearest neighbor, decision tree, and deep learning techniques such as Long Short-Term Memory and Convolution Neural Network. The work examines such learning methods using standard data set and the experimental results of sentiment analysis demonstrate the performance of various classifiers taken in terms of the precision, recall, F1-score, RoC-Curve, accuracy, running time and k fold cross validation and helps in appreciating the novelty of the several deep learning techniques and also giving the user an overview of choosing the right technique for their application.


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