7,030 research outputs found
Comparing Feature Detectors: A bias in the repeatability criteria, and how to correct it
Most computer vision application rely on algorithms finding local
correspondences between different images. These algorithms detect and compare
stable local invariant descriptors centered at scale-invariant keypoints.
Because of the importance of the problem, new keypoint detectors and
descriptors are constantly being proposed, each one claiming to perform better
(or to be complementary) to the preceding ones. This raises the question of a
fair comparison between very diverse methods. This evaluation has been mainly
based on a repeatability criterion of the keypoints under a series of image
perturbations (blur, illumination, noise, rotations, homotheties, homographies,
etc). In this paper, we argue that the classic repeatability criterion is
biased towards algorithms producing redundant overlapped detections. To
compensate this bias, we propose a variant of the repeatability rate taking
into account the descriptors overlap. We apply this variant to revisit the
popular benchmark by Mikolajczyk et al., on classic and new feature detectors.
Experimental evidence shows that the hierarchy of these feature detectors is
severely disrupted by the amended comparator.Comment: Fixed typo in affiliation
Affine Subspace Representation for Feature Description
This paper proposes a novel Affine Subspace Representation (ASR) descriptor
to deal with affine distortions induced by viewpoint changes. Unlike the
traditional local descriptors such as SIFT, ASR inherently encodes local
information of multi-view patches, making it robust to affine distortions while
maintaining a high discriminative ability. To this end, PCA is used to
represent affine-warped patches as PCA-patch vectors for its compactness and
efficiency. Then according to the subspace assumption, which implies that the
PCA-patch vectors of various affine-warped patches of the same keypoint can be
represented by a low-dimensional linear subspace, the ASR descriptor is
obtained by using a simple subspace-to-point mapping. Such a linear subspace
representation could accurately capture the underlying information of a
keypoint (local structure) under multiple views without sacrificing its
distinctiveness. To accelerate the computation of ASR descriptor, a fast
approximate algorithm is proposed by moving the most computational part (ie,
warp patch under various affine transformations) to an offline training stage.
Experimental results show that ASR is not only better than the state-of-the-art
descriptors under various image transformations, but also performs well without
a dedicated affine invariant detector when dealing with viewpoint changes.Comment: To Appear in the 2014 European Conference on Computer Visio
RISAS: A novel rotation, illumination, scale invariant appearance and shape feature
© 2017 IEEE. This paper presents a novel appearance and shape feature, RISAS, which is robust to viewpoint, illumination, scale and rotation variations. RISAS consists of a keypoint detector and a feature descriptor both of which utilise texture and geometric information present in the appearance and shape channels. A novel response function based on the surface normals is used in combination with the Harris corner detector for selecting keypoints in the scene. A strategy that uses the depth information for scale estimation and background elimination is proposed to select the neighbourhood around the keypoints in order to build precise invariant descriptors. Proposed descriptor relies on the ordering of both grayscale intensity and shape information in the neighbourhood. Comprehensive experiments which confirm the effectiveness of the proposed RGB-D feature when compared with CSHOT [1] and LOIND[2] are presented. Furthermore, we highlight the utility of incorporating texture and shape information in the design of both the detector and the descriptor by demonstrating the enhanced performance of CSHOT and LOIND when combined with RISAS detector
LIFT: Learned Invariant Feature Transform
We introduce a novel Deep Network architecture that implements the full
feature point handling pipeline, that is, detection, orientation estimation,
and feature description. While previous works have successfully tackled each
one of these problems individually, we show how to learn to do all three in a
unified manner while preserving end-to-end differentiability. We then
demonstrate that our Deep pipeline outperforms state-of-the-art methods on a
number of benchmark datasets, without the need of retraining.Comment: Accepted to ECCV 2016 (spotlight
FFD:Fast Feature Detector
Scale-invariance, good localization and robustness to noise and distortions
are the main properties that a local feature detector should possess. Most
existing local feature detectors find excessive unstable feature points that
increase the number of keypoints to be matched and the computational time of
the matching step. In this paper, we show that robust and accurate keypoints
exist in the specific scale-space domain. To this end, we first formulate the
superimposition problem into a mathematical model and then derive a closed-form
solution for multiscale analysis. The model is formulated via
difference-of-Gaussian (DoG) kernels in the continuous scale-space domain, and
it is proved that setting the scale-space pyramid's blurring ratio and
smoothness to 2 and 0.627, respectively, facilitates the detection of reliable
keypoints. For the applicability of the proposed model to discrete images, we
discretize it using the undecimated wavelet transform and the cubic spline
function. Theoretically, the complexity of our method is less than 5\% of that
of the popular baseline Scale Invariant Feature Transform (SIFT). Extensive
experimental results show the superiority of the proposed feature detector over
the existing representative hand-crafted and learning-based techniques in
accuracy and computational time. The code and supplementary materials can be
found at~{\url{https://github.com/mogvision/FFD}}
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