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Disentangling the sources of visual motion in a dynamic scene during self-movement or ego motion is important for autonomous navigation and tracking. In the dynamic image segments of a video frame containing independently moving objects, optic flow relative to the next frame is the sum of the motion fields generated due to camera and object motion. The traditional ego-motion estimation methods assume the scene to be static, and the recent deep learning-based methods do not separate pixel velocities into object- and ego-motion components. We propose a learning-based approach to predict both ego-motion parameters and object-motion field (OMF) from image sequences using a convolutional autoencoder while being robust to variations due to the unconstrained scene depth. This is achieved by: 1) training with continuous ego-motion constraints that allow solving for ego-motion parameters independently of depth and 2) learning a sparsely activated overcomplete ego-motion field (EMF) basis set, which eliminates the irrelevant components in both static and dynamic segments for the task of ego-motion estimation. In order to learn the EMF basis set, we propose a new differentiable sparsity penalty function that approximates the number of nonzero activations in the bottleneck layer of the autoencoder and enforces sparsity more effectively than L1- and L2-norm-based penalties. Unlike the existing direct ego-motion estimation methods, the predicted global EMF can be used to extract OMF directly by comparing it against the optic flow. Compared with the state-of-the-art baselines, the proposed model performs favorably on pixelwise object- and ego-motion estimation tasks when evaluated on real and synthetic data sets of dynamic scenes.
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Framework of integrating 2D points and curves for tracking of 3D non-rigid motion and structure
We present a method for 3D non-rigid motion tracking and structure reconstruction from 2D points and curve segments from a sequence of perspective images. The 3D locations of features in the first frame are known. The 3D affine motion model is used to describe the nonrigid motion. The results from synthetic and real data are presented. The applications include: lip tracking, MPEG4 face player, and burn scar assessment. The results show that: 1) curve segments are more robust under noise (observed from synthetic data with different Gaussian noise level); and 2) using both feature yields a significant performance gain in real data.
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- Award ID(s):
- 9724422
- PAR ID:
- 10346812
- Date Published:
- Journal Name:
- International Conference on Pattern Recognition
- Volume:
- 3
- Page Range / eLocation ID:
- 823 to 826
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/ICPR.2000.903671
