4 research outputs found
Robust Stabilised Visual Tracker for Vehicle Tracking
Visual tracking is performed in a stabilised video. If the input video to the tracker algorithm is itself destabilised, incorrect motion vectors will cause a serious drift in tracking. Therefore video stabilisation is must before tracking. A novel algorithm is developed which simultaneously takes care of video stabilisation and target tracking. Target templates in just previous frame are stored in positive and negative repositories followed by Affine mapping. Then optimised affine parameters are used to stabilise the video. Target of interest in the next frame is approximated using linear combinations of previous target templates. Proposed modified L1 minimisation method is used to solve sparse representation of target in the target template subspace. Occlusion problem is minimised using the inherent energy of coefficients. Accurate tracking results have been obtained in destabilised videos
Deformable Groupwise Registration Using a Locally Low-Rank Dissimilarity Metric for Myocardial Strain Estimation from Cardiac Cine MRI Images
Objective: Cardiovascular magnetic resonance-feature tracking (CMR-FT)
represents a group of methods for myocardial strain estimation from cardiac
cine MRI images. Established CMR-FT methods are mainly based on optical flow or
pairwise registration. However, these methods suffer from either inaccurate
estimation of large motion or drift effect caused by accumulative tracking
errors. In this work, we propose a deformable groupwise registration method
using a locally low-rank (LLR) dissimilarity metric for CMR-FT. Methods: The
proposed method (Groupwise-LLR) tracks the feature points by a groupwise
registration-based two-step strategy. Unlike the globally low-rank (GLR)
dissimilarity metric, the proposed LLR metric imposes low-rankness on local
image patches rather than the whole image. We quantitatively compared
Groupwise-LLR with the Farneback optical flow, a pairwise registration method,
and a GLR-based groupwise registration method on simulated and in vivo
datasets. Results: Results from the simulated dataset showed that Groupwise-LLR
achieved more accurate tracking and strain estimation compared with the other
methods. Results from the in vivo dataset showed that Groupwise-LLR achieved
more accurate tracking and elimination of the drift effect in late-diastole.
Inter-observer reproducibility of strain estimates was similar between all
studied methods. Conclusion: The proposed method estimates myocardial strains
more accurately due to the application of a groupwise registration-based
tracking strategy and an LLR-based dissimilarity metric. Significance: The
proposed CMR-FT method may facilitate more accurate estimation of myocardial
strains, especially in diastole, for clinical assessments of cardiac
dysfunction
A ROBUST BLOCK BASED IMAGE/VIDEO REGISTRATION APPROACH FOR MOBILE IMAGING DEVICES 1 A Robust Block Based Image/Video Registration Approach for Mobile Imaging Devices
Abstract—Digital video stabilization enables to acquire video sequences without disturbing jerkiness by compensating unwanted camera movements. In this paper we propose a novel fast image registration algorithm based on block matching. Unreliable motion vectors (i.e., not related with jitter movements) are properly filtered out by making use of ad-hoc rules taking into account local similarity, local activity and matching effectiveness. Moreover, a temporal analysis of the relative error computed at each frame has been performed. Reliable information is then used to retrieve inter-frame transformation parameters. Experiments on real cases confirm the effectiveness of the proposed approach even in critical conditions. Index Terms—Video stabilization, motion estimation, block matching. I
Model-Based Environmental Visual Perception for Humanoid Robots
The visual perception of a robot should answer two fundamental questions: What? and Where? In order to properly and efficiently reply to these questions, it is essential to establish a bidirectional coupling between the external stimuli and the internal representations. This coupling links the physical world with the inner abstraction models by sensor transformation, recognition, matching and optimization algorithms. The objective of this PhD is to establish this sensor-model coupling