On smoothness of a vector field-application to optical flow

1988 ◽  
Vol 10 (6) ◽  
pp. 943-949 ◽  
Author(s):  
A. Mitiche ◽  
R. Grisell ◽  
J.K. Aggarwal
Keyword(s):  
Vector Field ◽  
Optical Flow ◽  
Field Application

Images, Imagination, and Movement: Pictorial Representations and Their Development in the Work of James Gibson

Perception ◽  
10.1068/p2976 ◽  
2000 ◽  
Vol 29 (6) ◽  
pp. 635-648 ◽  
Author(s):  
James E Cutting
Keyword(s):  
Vector Field ◽  
Optical Flow ◽  
Spherical Representation ◽  
Pictorial Representations ◽  
The Relationship

For more than 30 years James Gibson studied pictures and he studied motion, particularly the relationship between movement through an environment and its visual consequences. For the latter, he also struggled with how best to present his ideas to students and fellow researchers, and employed various representations and formats. This article explores the relationships between the concepts of the fidelity of pictures (an idea he first promoted and later eschewed) and evocativeness as applied to his images. Gibson ended his struggle with an image of a bird flying over a plane surrounded by a spherical representation of a vector field, an image high in evocativeness but less than completely faithful to optical flow.

scholarly journals Motion Vector Field Estimation Using Brightness Constancy Assumption and Epipolar Geometry Constraint

2014 ◽  
Vol II-1 ◽  
pp. 9-16 ◽  
Author(s):  
S. Hosseinyalamdary ◽  
A. Yilmaz
Keyword(s):  
Vector Field ◽  
Optical Flow ◽  
Motion Vector ◽  
Epipolar Geometry ◽  
Estimation Methods ◽  
Brightness Constancy ◽  
Flow Estimation ◽  
Optical Flow Estimation ◽  
Motion Vector Field ◽  
Field Estimation

In most Photogrammetry and computer vision tasks, finding the corresponding points among images is required. Among many, the Lucas-Kanade optical flow estimation has been employed for tracking interest points as well as motion vector field estimation. This paper uses the IMU measurements to reconstruct the epipolar geometry and it integrates the epipolar geometry constraint with the brightness constancy assumption in the Lucas-Kanade method. The proposed method has been tested using the KITTI dataset. The results show the improvement in motion vector field estimation in comparison to the Lucas-Kanade optical flow estimation. The same approach has been used in the KLT tracker and it has been shown that using epipolar geometry constraint can improve the KLT tracker. It is recommended that the epipolar geometry constraint is used in advanced variational optical flow estimation methods.

Vector-Field dynamic X-ray (VF-DXR) using Optical Flow Method

2021 ◽  
pp. 20201210
Author(s):  
Takuya Hino ◽  
Akinori Tsunomori ◽  
Takenori Fukumoto ◽  
Akinori Hata ◽  
Masako Ueyama ◽  
...  
Keyword(s):  
Vector Field ◽  
Optical Flow ◽  
Color Coding ◽  
X Ray ◽  
Flow Method ◽  
Optical Flow Method ◽  
Copd Patients ◽  
Vector Projection ◽  
Field Dynamic ◽  
Pixel Value

Objectives: To explore the feasibility of Vector-Field DXR (VF-DXR) using optical flow method (OFM). Methods: Five healthy volunteers and five COPD patients were studied. DXR was performed in the standing position using a prototype X-ray system (Konica Minolta Inc., Tokyo, Japan). During the examination, participants took several tidal breaths and one forced breath. DXR image file was converted to the videos with different frames per second (fps): 15 fps, 7.5 fps, five fps, three fps, and 1.5 fps. Pixel-value gradient was calculated by the serial change of pixel value, which was subsequently converted mathematically to motion vector using OFM. Color-coding map and vector projection into horizontal and vertical components were also tested. Results: Dynamic motion of lung and thorax was clearly visualized using VF-DXR with an optimal frame rate of 5 fps. Color-coding map and vector projection into horizontal and vertical components were also presented. VF-DXR technique was also applied in COPD patients. Conclusion: The feasibility of VF-DXR was demonstrated with small number of healthy subjects and COPD patients. Advances in knowledge: A new Vector-Field Dynamic X-ray (VF-DXR) technique is feasible for dynamic visualization of lung, diaphragms, thoracic cage, and cardiac contour.

scholarly journals A Morphing-Based Technique for the Verification of Precipitation Forecasts

2015 ◽  
Vol 144 (1) ◽  
pp. 295-313 ◽  
Author(s):  
Fan Han ◽  
Istvan Szunyogh
Keyword(s):  
Vector Field ◽  
Optical Flow ◽  
Quantitative Information ◽  
Precipitation Forecast ◽  
Total Precipitation ◽  
Objective Criterion ◽  
Maximum Displacement ◽  
Matching Algorithm ◽  
Pyramid Matching ◽  
Selection Of

Abstract This paper describes a morphing-based approach for the verification of precipitation forecasts. This approach employs a pyramid matching algorithm to morph the precipitation features in a forecast into features that match the related precipitation features in the verifying analysis (observations) as closely as possible. The algorithm computes an optical flow (vector field) that maps the original forecast features into the morphed forecast features. The optical flow also provides quantitative information about the error in the location of the forecast features. This information, combined with information about the error in the prediction of the total precipitation over the verification domain, is used to quantify the structure error in the precipitation forecast. The proposed approach has three novel aspects compared to the published morphing-based verification strategies. First, it imposes a constraint on the pyramid matching algorithm to prevent overconvergence toward strong precipitation features during morphing. Second, it introduces an objective criterion for the selection of the subsampling parameter to avoid splitting or distorting features due to an arbitrary maximum displacement limit. Third, the proposed definitions of the location and structure errors are new. The behavior of the proposed multivariate verification metrics is investigated by applications to both idealized and numerical forecast examples.

Motion correction in PET/CT

2005 ◽  
Vol 44 (S 01) ◽  
pp. S46-S50 ◽  
Author(s):  
M. Dawood ◽  
N. Lang ◽  
F. Büther ◽  
M. Schäfers ◽  
O. Schober ◽  
...  
Keyword(s):  
Optical Flow ◽  
Motion Correction ◽  
Motion Vector ◽  
Emission Tomography ◽  
Cardiac Pet ◽  
Novel Approach ◽  
Positron Emission ◽  
Pet Ct ◽  
Flow Algorithm ◽  
Motion Vector Field

Summary:Motion in PET/CT leads to artifacts in the reconstructed PET images due to the different acquisition times of positron emission tomography and computed tomography. The effect of motion on cardiac PET/CT images is evaluated in this study and a novel approach for motion correction based on optical flow methods is outlined. The Lukas-Kanade optical flow algorithm is used to calculate the motion vector field on both simulated phantom data as well as measured human PET data. The motion of the myocardium is corrected by non-linear registration techniques and results are compared to uncorrected images.

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