scholarly journals Wavelet-Based Optical Flow Analysis for Background-Oriented Schlieren Image Processing

AIAA Journal ◽  
2021 ◽  
pp. 1-8
Author(s):  
Bryan E. Schmidt ◽  
Mark R. Woike
2021 ◽  
Author(s):  
Bryan Eric Schmidt ◽  
Mark Woike

A wavelet-based optical flow analysis (wOFA) method for processing background oriented schlieren (BOS) images is presented and demonstrated on synthetic and experimental data. Optical flow is inherently well-suited to BOS, since the background pattern and lighting conditions are specified and controlled by the user, and can be chosen to play to the strengths of optical flow processing. Analysis of the synthetic BOS data show that a 2D sinusoidal background produces the highest reconstruction accuracy for both wOFA and iterative least squares (ILS) algorithms. wOFA outperforms ILS in terms of overall accuracy for displacement fields with sufficiently high spatial frequency content. In addition, wOFA provides higher spatial resolution, about an order of magnitude in terms of the total number of pixels in the final BOS image. Finally, wOFA is demonstrated on two sets of experimental data, a heat gun plume experiment with nearly ideal imaging characteristics, and experiments in a supersonic wind tunnel flow with more realistic restrictions on the acquisition of images. BOS images computed with wOFA are shown to have higher spatial resolution and sensitivity than ILS, without introducing additional noise. Therefore, wOFA of BOS images are able to reveal flow features not detected by ILS analysis.


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

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.


Compiler ◽  
2015 ◽  
Vol 4 (2) ◽  
Author(s):  
Anton Setiawan Honggowibowo ◽  
Sapto Aji Wibowo

Technological developments in the field of computers getting faster requires the ability of each person to be able to follow the progress of computer development. Computer vision applications is an application that allows the computer to have the ability to be able to capture and understand the data, such as image and make decisions based on the data from the real object movement that was in front of the webcam and then the data obtained is processed in accordance with user needs. Digital image of a real object is captured by a webcam can be done in various ways making objects. In this research, object retrieval by utilizing activity in this object is that caught on webcam pen is through the form and motion of objects. Once an object is detected then the object is to move the cursor on a computer. To be able to perform image processing, this application uses OpenCV components. Meanwhile, to be able to perform tracking of the cursor object using optical flow method. Cursor moves when the pen has a rectangular sides and parallel to the pen position frame of grabber.


2017 ◽  
Vol 28 (5) ◽  
pp. 055208 ◽  
Author(s):  
Qianglong Zhong ◽  
Hua Yang ◽  
Zhouping Yin

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.


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