361 research outputs found
GOGMA: Globally-Optimal Gaussian Mixture Alignment
Gaussian mixture alignment is a family of approaches that are frequently used
for robustly solving the point-set registration problem. However, since they
use local optimisation, they are susceptible to local minima and can only
guarantee local optimality. Consequently, their accuracy is strongly dependent
on the quality of the initialisation. This paper presents the first
globally-optimal solution to the 3D rigid Gaussian mixture alignment problem
under the L2 distance between mixtures. The algorithm, named GOGMA, employs a
branch-and-bound approach to search the space of 3D rigid motions SE(3),
guaranteeing global optimality regardless of the initialisation. The geometry
of SE(3) was used to find novel upper and lower bounds for the objective
function and local optimisation was integrated into the scheme to accelerate
convergence without voiding the optimality guarantee. The evaluation
empirically supported the optimality proof and showed that the method performed
much more robustly on two challenging datasets than an existing
globally-optimal registration solution.Comment: Manuscript in press 2016 IEEE Conference on Computer Vision and
Pattern Recognitio
Improving Object Localization with Fitness NMS and Bounded IoU Loss
We demonstrate that many detection methods are designed to identify only a
sufficently accurate bounding box, rather than the best available one. To
address this issue we propose a simple and fast modification to the existing
methods called Fitness NMS. This method is tested with the DeNet model and
obtains a significantly improved MAP at greater localization accuracies without
a loss in evaluation rate, and can be used in conjunction with Soft NMS for
additional improvements. Next we derive a novel bounding box regression loss
based on a set of IoU upper bounds that better matches the goal of IoU
maximization while still providing good convergence properties. Following these
novelties we investigate RoI clustering schemes for improving evaluation rates
for the DeNet wide model variants and provide an analysis of localization
performance at various input image dimensions. We obtain a MAP of 33.6%@79Hz
and 41.8%@5Hz for MSCOCO and a Titan X (Maxwell). Source code available from:
https://github.com/lachlants/denetComment: CVPR2018 Main Conference (Poster
Sample and Filter: Nonparametric Scene Parsing via Efficient Filtering
Scene parsing has attracted a lot of attention in computer vision. While
parametric models have proven effective for this task, they cannot easily
incorporate new training data. By contrast, nonparametric approaches, which
bypass any learning phase and directly transfer the labels from the training
data to the query images, can readily exploit new labeled samples as they
become available. Unfortunately, because of the computational cost of their
label transfer procedures, state-of-the-art nonparametric methods typically
filter out most training images to only keep a few relevant ones to label the
query. As such, these methods throw away many images that still contain
valuable information and generally obtain an unbalanced set of labeled samples.
In this paper, we introduce a nonparametric approach to scene parsing that
follows a sample-and-filter strategy. More specifically, we propose to sample
labeled superpixels according to an image similarity score, which allows us to
obtain a balanced set of samples. We then formulate label transfer as an
efficient filtering procedure, which lets us exploit more labeled samples than
existing techniques. Our experiments evidence the benefits of our approach over
state-of-the-art nonparametric methods on two benchmark datasets.Comment: Please refer to the CVPR-2016 version of this manuscrip
Encouraging LSTMs to Anticipate Actions Very Early
In contrast to the widely studied problem of recognizing an action given a
complete sequence, action anticipation aims to identify the action from only
partially available videos. As such, it is therefore key to the success of
computer vision applications requiring to react as early as possible, such as
autonomous navigation. In this paper, we propose a new action anticipation
method that achieves high prediction accuracy even in the presence of a very
small percentage of a video sequence. To this end, we develop a multi-stage
LSTM architecture that leverages context-aware and action-aware features, and
introduce a novel loss function that encourages the model to predict the
correct class as early as possible. Our experiments on standard benchmark
datasets evidence the benefits of our approach; We outperform the
state-of-the-art action anticipation methods for early prediction by a relative
increase in accuracy of 22.0% on JHMDB-21, 14.0% on UT-Interaction and 49.9% on
UCF-101.Comment: 13 Pages, 7 Figures, 11 Tables. Accepted in ICCV 2017. arXiv admin
note: text overlap with arXiv:1611.0552
Bringing Background into the Foreground: Making All Classes Equal in Weakly-supervised Video Semantic Segmentation
Pixel-level annotations are expensive and time-consuming to obtain. Hence,
weak supervision using only image tags could have a significant impact in
semantic segmentation. Recent years have seen great progress in
weakly-supervised semantic segmentation, whether from a single image or from
videos. However, most existing methods are designed to handle a single
background class. In practical applications, such as autonomous navigation, it
is often crucial to reason about multiple background classes. In this paper, we
introduce an approach to doing so by making use of classifier heatmaps. We then
develop a two-stream deep architecture that jointly leverages appearance and
motion, and design a loss based on our heatmaps to train it. Our experiments
demonstrate the benefits of our classifier heatmaps and of our two-stream
architecture on challenging urban scene datasets and on the YouTube-Objects
benchmark, where we obtain state-of-the-art results.Comment: 11 pages, 4 figures, 7 tables, Accepted in ICCV 201
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