Accuracy evaluation of sub-pixel structural vibration measurements through optical flow analysis of a video sequence

Measurement ◽  
2017 ◽  
Vol 95 ◽  
pp. 166-172 ◽  
Author(s):  
D.H. Diamond ◽  
P.S. Heyns ◽  
A.J. Oberholster
Author(s):  
Antonis Ioannidis ◽  
Vasileios Chasanis ◽  
Aristidis Likas

Most of the existing approaches for camera motion detection are based on optical flow analysis and the use of the affine motion model. However, these methods are computationally expensive due to the cost of optical flow estimation and may be inefficient in the presence of moving objects whose motion is independent of the camera motion. We present an effective approach to detect camera motions by considering four trapezoidal regions in each frame and computing the horizontal and vertical translations of those regions. Then, simple decision rules based on the translations of the regions are employed in order to decide for the existence and the type of camera motion in each frame. In this way, three signals are constructed (pan, tilt, zoom) which are subsequently filtered to improve the robustness of the method. Comparative experiments on a variety of videos indicate that our method efficiently detects any type of camera motion (pan, tilt, zoom), even in the case where moving objects exist in the video sequence.


2018 ◽  
Vol 8 (4) ◽  
pp. 512
Author(s):  
Mark Schult ◽  
Christoph Drobek ◽  
Hermann Seitz
Keyword(s):  

Action recognition (AR) plays a fundamental role in computer vision and video analysis. We are witnessing an astronomical increase of video data on the web and it is difficult to recognize the action in video due to different view point of camera. For AR in video sequence, it depends upon appearance in frame and optical flow in frames of video. In video spatial and temporal components of video frames features play integral role for better classification of action in videos. In the proposed system, RGB frames and optical flow frames are used for AR with the help of Convolutional Neural Network (CNN) pre-trained model Alex-Net extract features from fc7 layer. Support vector machine (SVM) classifier is used for the classification of AR in videos. For classification purpose, HMDB51 dataset have been used which includes 51 Classes of human action. The dataset is divided into 51 action categories. Using SVM classifier, extracted features are used for classification and achieved best result 95.6% accuracy as compared to other techniques of the state-of- art.v


2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaoping Guo

Traditional text annotation-based video retrieval is done by manually labeling videos with text, which is inefficient and highly subjective and generally cannot accurately describe the meaning of videos. Traditional content-based video retrieval uses convolutional neural networks to extract the underlying feature information of images to build indexes and achieves similarity retrieval of video feature vectors according to certain similarity measure algorithms. In this paper, by studying the characteristics of sports videos, we propose the histogram difference method based on using transfer learning and the four-step method based on block matching for mutation detection and fading detection of video shots, respectively. By adaptive thresholding, regions with large frame difference changes are marked as candidate regions for shots, and then the shot boundaries are determined by mutation detection algorithm. Combined with the characteristics of sports video, this paper proposes a key frame extraction method based on clustering and optical flow analysis, and experimental comparison with the traditional clustering method. In addition, this paper proposes a key frame extraction algorithm based on clustering and optical flow analysis for key frame extraction of sports video. The algorithm effectively removes the redundant frames, and the extracted key frames are more representative. Through extensive experiments, the keyword fuzzy finding algorithm based on improved deep neural network and ontology semantic expansion proposed in this paper shows a more desirable retrieval performance, and it is feasible to use this method for video underlying feature extraction, annotation, and keyword finding, and one of the outstanding features of the algorithm is that it can quickly and effectively retrieve the desired video in a large number of Internet video resources, reducing the false detection rate and leakage rate while improving the fidelity, which basically meets people’s daily needs.


2020 ◽  
Vol 31 (12) ◽  
pp. 1246-1258 ◽  
Author(s):  
Maik Drechsler ◽  
Lukas F. Lang ◽  
Layla Al-Khatib ◽  
Hendrik Dirks ◽  
Martin Burger ◽  
...  

Here we introduce an optical flow motion estimation approach to study microtubule (MT) orientation in the Drosophila oocyte, a cell displaying substantial cytoplasmic streaming. We show that MT polarity is affected by the regime of these flows and, furthermore, that the presence of flows is necessary for MTs to adopt their proper polarity.


Author(s):  
Shunyao Zhang ◽  
Tian Wang ◽  
Chuanyun Wang ◽  
Yan Wang ◽  
Guangcun Shan ◽  
...  

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