pinecone/core-2020-05-10-deduplication huggingface dataset:
Occlusion and Motion Reasoning for Long-term Tracking

International audienceObject tracking is a reoccurring problem in computer vision. Tracking-by-detection approaches, in particular Struck (Hare et al., 2011), have shown to be competitive in recent evaluations. However, such approaches fail in the presence of long-term occlusions as well as severe viewpoint changes of the object. In this paper we propose a principled way to combine occlusion and motion reasoning with a tracking-by-detection approach. Occlusion and motion reasoning is based on state-of-the-art long-term trajectories which are labeled as object or background tracks with an energy-based formulation. The overlap between labeled tracks and detected regions allows to identify occlusions. The motion changes of the object between consecutive frames can be estimated robustly from the geometric relation between object trajectories. If this geometric change is significant, an additional detector is trained. Experimental results show that our tracker obtains state-of-the-art results and handles occlusion and viewpoints changes better than competing tracking methods
FPM: Fine Pose Parts-Based Model with 3D CAD Models

We introduce a novel approach to the problem of localizing objects in an image and estimating their fine-pose. Given exact CAD models, and a few real training images with aligned models, we propose to leverage the geometric information from CAD models and appearance information from real images to learn a model that can accurately estimate fine pose in real images. Specifically, we propose FPM, a fine pose parts-based model, that combines geometric information in the form of shared 3D parts in deformable part based models, and appearance information in the form of objectness to achieve both fast and accurate fine pose estimation. Our method significantly outperforms current state-of-the-art algorithms in both accuracy and speed
Category-specific video summarization

International audienceIn large video collections with clusters of typical categories, such as ''birthday party'' or ''flash-mob'', category-specific video summarization can produce higher quality video summaries than unsupervised approaches that are blind to the video category. Given a video from a known category, our approach first efficiently performs a temporal segmentation into semantically-consistent segments, delimited not only by shot boundaries but also general change points. Then, equipped with an SVM classifier, our approach assigns importance scores to each segment. The resulting video assembles the sequence of segments with the highest scores. The obtained video summary is therefore both short and highly informative. Experimental results on videos from the multimedia event detection (MED) dataset of TRECVID'11 show that our approach produces video summaries with higher relevance than the state of the art
Assessing the Quality of Actions

While recent advances in computer vision have provided reliable methods to recognize actions in both images and videos, the problem of assessing how well people perform actions has been largely unexplored in computer vision. Since methods for assessing action quality have many real-world applications in healthcare, sports, and video retrieval, we believe the computer vision community should begin to tackle this challenging problem. To spur progress, we introduce a learning-based framework that takes steps towards assessing how well people perform actions in videos. Our approach works by training a regression model from spatiotemporal pose features to scores obtained from expert judges. Moreover, our approach can provide interpretable feedback on how people can improve their action. We evaluate our method on a new Olympic sports dataset, and our experiments suggest our framework is able to rank the athletes more accurately than a non-expert human. While promising, our method is still a long way to rivaling the performance of expert judges, indicating that there is significant opportunity in computer vision research to improve on this difficult yet important task.National Science Foundation (U.S.). Graduate Research FellowshipGoogle (Firm) (Research Award)United States. Office of Naval Research. Multidisciplinary University Research Initiative (N000141010933
Numerical inversion of SRNFs for efficient elastic shape analysis of star-shaped objects.

The elastic shape analysis of surfaces has proven useful in several application areas, including medical image analysis, vision, and graphics.\ud
This approach is based on defining new mathematical representations of parameterized surfaces, including the square root normal field (SRNF), and then using the L2 norm to compare their shapes. Past work is based on using the pullback of the L2 metric to the space of surfaces, performing statistical analysis under this induced Riemannian metric. However, if one can estimate the inverse of the SRNF mapping, even approximately, a very efficient framework results: the surfaces, represented by their SRNFs, can be efficiently analyzed using standard Euclidean tools, and only the final results need be mapped back to the surface space. Here we describe a procedure for inverting SRNF maps of star-shaped surfaces, a special case for which analytic results can be obtained. We test our method via the classification of 34 cases of ADHD (Attention Deficit Hyperactivity Disorder), plus controls, in the Detroit Fetal Alcohol and Drug Exposure Cohort study. We obtain state-of-the-art results
Weakly Supervised Action Labeling in Videos Under Ordering Constraints

International audienceWe are given a set of video clips, each one annotated with an ordered list of actions, such as "walk" then "sit" then "answer phone" extracted from, for example, the associated text script. We seek to tem- porally localize the individual actions in each clip as well as to learn a discriminative classifier for each action. We formulate the problem as a weakly supervised temporal assignment with ordering constraints. Each video clip is divided into small time intervals and each time interval of each video clip is assigned one action label, while respecting the order in which the action labels appear in the given annotations. We show that the action label assignment can be determined together with learning a classifier for each action in a discriminative manner. We evaluate the proposed model on a new and challenging dataset of 937 video clips with a total of 787720 frames containing sequences of 16 different actions from 69 Hollywood movies
A MAP-Estimation Framework for Blind Deblurring Using High-Level Edge Priors

International audienceIn this paper we propose a general MAP-estimation framework for blind image deconvolution that allows the incorporation of powerful priors regarding predicting the edges of the latent image, which is known to be a crucial factor for the success of blind deblurring. This is achieved in a principled, robust and unified manner through the use of a global energy function that can take into account multiple constraints. Based on this framework, we show how to successfully make use of a particular prior of this type that is quite strong and also applicable to a wide variety of cases. It relates to the strong structural regularity that is exhibited by many scenes, and which affects the location and distribution of the corresponding image edges. We validate the excellent performance of our approach through an extensive set of experimental results and comparisons to the state-of-the-art
Tubular structure filtering by ranking orientation responses of path operators

International audienceThin objects in 3D volumes, for instance vascular networks in medical imaging or various kinds of fibres in materials science, have been of interest for some time to computer vision. Particularly, tubular objects are everywhere elongated in one principal direction –which varies spatially– and are thin in the other two perpendicular directions. Filters for detecting such structures use for instance an analysis of the three principal directions of the Hessian, which is a local feature. In this article, we present a low-level tubular structure detection filter. This filter relies on paths, which are semi-global features that avoid any blurring effect induced by scale-space convolution. More precisely, our filter is based on recently developed morphological path operators. These require sampling only in a few principal directions, are robust to noise and do not assume feature regularity. We show that by ranking the directional response of this operator, we are further able to efficiently distinguish between blob, thin planar and tubular structures. We validate this approach on several applications, both from a qualitative and a quantitative point of view, demonstrating noise robustness and an efficient response on tubular structures
On Mean Pose and Variability of 3D Deformable Models

International audienceWe present a novel methodology for the analysis of complex object shapes in motion observed by multiple video cameras. In particular, we propose to learn local surface rigidity probabilities (i.e., deformations), and to estimate a mean pose over a temporal sequence. Local deformations can be used for rigidity-based dynamic surface segmentation, while a mean pose can be used as a sequence keyframe or a cluster prototype and has therefore numerous applications, such as motion synthesis or sequential alignment for compression or morphing. We take advantage of recent advances in surface tracking techniques to formulate a generative model of 3D temporal sequences using a probabilistic framework, which conditions shape fitting over all frames to a simple set of intrinsic surface rigidity properties. Surface tracking and rigidity variable estimation can then be formulated as an Expectation-Maximization inference problem and solved by alternatively minimizing two nested fixed point iterations. We show that this framework provides a new fundamental building block for various applications of shape analysis, and achieves comparable tracking performance to state of the art surface tracking techniques on real datasets, even compared to approaches using strong kinematic priors such as rigid skeletons
Intrinsic textures for relightable free-viewpoint video

This paper presents an approach to estimate the intrinsic texture properties (albedo, shading, normal) of scenes from multiple view acquisition under unknown illumination conditions. We introduce the concept of intrinsic textures, which are pixel-resolution surface textures representing the intrinsic appearance parameters of a scene. Unlike previous video relighting methods, the approach does not assume regions of uniform albedo, which makes it applicable to richly textured scenes. We show that intrinsic image methods can be used to refine an initial, low-frequency shading estimate based on a global lighting reconstruction from an original texture and coarse scene geometry in order to resolve the inherent global ambiguity in shading. The method is applied to relighting of free-viewpoint rendering from multiple view video capture. This demonstrates relighting with reproduction of fine surface detail. Quantitative evaluation on synthetic models with textured appearance shows accurate estimation of intrinsic surface reflectance properties. © 2014 Springer International Publishing
Match Selection and Refinement for Highly Accurate Two-View Structure from Motion

International audienceWe present an approach to enhance the accuracy of structure from motion (SfM) in the two-view case. We first answer the question: " fewer data with higher accuracy, or more data with less accuracy? " For this, we establish a relation between SfM errors and a function of the number of matches and their epipolar errors. Using an accuracy estima-tor of individual matches, we then propose a method to select a subset of matches that has a good quality vs. quantity compromise. We also propose a variant of least squares matching to refine match locations based on a focused grid and a multi-scale exploration. Experiments show that both selection and refinement contribute independently to a better accuracy. Their combination reduces errors by a factor of 1.1 to 2.0 for rotation, and 1.6 to 3.8 for translation
Cloud and Star Formation in Spiral Arms

We present the results from simulations of GMC formation in spiral galaxies.
First we discuss cloud formation by cloud-cloud collisions, and gravitational
instabilities, arguing that the former is prevalent at lower galactic surface
densities and the latter at higher. Cloud masses are also limited by stellar
feedback, which can be effective before clouds reach their maximum mass. We
show other properties of clouds in simulations with different levels of
feedback. With a moderate level of feedback, properties such as cloud rotations
and virial parameters agree with observations. Without feedback, an unrealistic
population of overly bound clouds develops. Spiral arms are not found to
trigger star formation, they merely gather gas into more massive GMCs. We
discuss in more detail interactions of clouds in the ISM, and argue that these
are more complex than early ideas of cloud-cloud collisions. Finally we show
ongoing work to determine whether the Milky Way is a flocculent or grand design
spiral.Comment: 10 pages, 5 figures, to be published in Seychelles conference
  "Lessons from the Local Group", ed. K. C. Freeman, B. G. Elmegreen, D. L.
  Block, and M. Woolway (Dordrecht: Springer), 201
Chemical Evolution of M31

We review chemical evolution models developed for M31 as well as the
abundance determinations available for this galaxy. Then we present a recent
chemical evolution model for M31 including radial gas flows and galactic
fountains along the disk, as well as a model for the bulge. Our models are
predicting the evolution of the abundances of several chemical species such as
H, He, C, N, O, Ne, Mg, Si, S, Ca and Fe. From comparison between model
predictions and observations we can derive some constraints on the evolution of
the disk and the bulge of M31. We reach the conclusions that Andromeda must
have evolved faster than the Milky Way and inside-out, and that its bulge
formed much faster than the disk on a timescale $\leq$ 0.5 Gyr. Finally, we
present a study where we apply the model developed for the disk of M31 in order
to study the probability of finding galactic habitable zones in this galaxy.Comment: To be published in:"Lessons from the Local Group: A Conference in
  Honour of David Block and Bruce Elmegreen" Editors: Prof. Dr. Kenneth
  Freeman, Dr. Bruce Elmegreen, Prof. Dr. David Block, Matthew Woolway,
  Springe
Lessons from the Milky Way: the Kapteyn Universe

Jacobus Cornelius Kapteyn (1851-1922) presented a model for the distribution
of stars in space together with a dynamical interpretation in terms of an
equilibrium between the gravitational field of the stars and their random
motion and rotation. In the vertical direction Kapteyn's results are
substantially correct. Usually the Kapteyn Universe is described as being
flawed due to neglect of interstellar absorption. Kapteyn was led to adopt this
on the basis of widely accepted evidence by Shapley on an absence of reddening
of stars in globular clusters. But another, equally important misconception was
Kapteyn's interpretation of the two Star Streams as manifestations of two
groups of stars rotating around a center in opposite directions. This was
supported by the observation of very different mixes in stellar types in the
two streams. Had Kapteyn adopted the absorption as he himself had determined it
he would not have been able to arrive at a consistent picture.Comment: To appear in LESSONS FROM THE LOCAL GROUP: A Conference in Honour of
  David Block and Bruce Elmegreen, eds. Freeman, K.C., Elmegreen, B.G., Block,
  D.L.and Woolway, M., Springer: New Yor
Morphological transformations of Dwarf Galaxies in the Local Group

In the Local Group there are three main types of dwarf galaxies: Dwarf
Irregulars, Dwarf Spheroidals, and Dwarf Ellipticals. Intermediate/transitional
types are present as well. This contribution reviews the idea that the present
day variety of dwarf galaxy morphologies in the Local Group might reveal the
existence of a transformation chain of events, of which any particular dwarf
galaxy represents a manifestation of a particular stage. In other words, all
dwarf galaxies that now are part of the Local Group would have formed
identically in the early universe, but then evolved differently because of
morphological transformations induced by dynamical processes like galaxy
harassment, ram pressure stripping, photo-evaporation, and so forth. We start
describing the population of dwarf galaxies and their spatial distribution in
the LG. Then, we describe those phenomena that can alter the morphology of a
dwarf galaxies, essentially by removing, partially or completely, their gas
content. Lastly, we discuss morphological signatures in the Local Group Dwarf
Galaxies that can be attributed to different dynamical phenomena. While it is
difficult to identify a unique and continuous transformation sequence, we have
now a reasonable understanding of the basic evolutionary paths that lead to the
various dwarf galaxy types.Comment: 12 pages, 4 eps figures, review given at Seychelles conference
  "Lessons from the Local Group", ed. K. C. Freeman, B. G. Elmegreen, D. L.
  Block, and M. Woolway (Dordrecht: Springer), in press, 201
The Panchromatic Hubble Andromeda Treasury. Progression of Large-Scale
  Star Formation across Space and Time in M31

We investigate the clustering of early-type stars younger than 300 Myr on
galactic scales in M31. Based on the stellar photometric catalogs of the
Panchromatic Hubble Andromeda Treasury program that also provides stellar
parameters derived from the individual energy distributions, our analysis is
focused on the young stars in three star-forming regions, located at
galactocentric distances of about 5, 10, and 15 kpc, corresponding to the inner
spiral arms, the ring structure, and the outer arm, respectively. We apply the
two-point correlation function to our selected sample to investigate the
clustering behavior of these stars across different time- and length-scales. We
find that young stellar structure survives across the whole extent of M31
longer than 300 Myr. Stellar distribution in all regions appears to be
self-similar, with younger stars being systematically more strongly clustered
than the older, which are more dispersed. The observed clustering is
interpreted as being induced by turbulence, the driving source for which is
probably gravitational instabilities driven by the spiral arms, which are
stronger closer to the galactic centre.Comment: 10 pages, 5 figures. To appear in "LESSONS FROM THE LOCAL GROUP - A
  Conference in Honour of David Block and Bruce Elmegreen" eds. Freeman, K.C.,
  Elmegreen, B.G., Block, D.L. & Woolway, M. (Springer: New York
Structure and Evolution of Dwarf Galaxies

Different structural parameter correlations show how classical bulge
components and elliptical galaxies are different from spiral and S0 galaxy
disks, irregular (Im) galaxies, and spheroidal (Sph) galaxies. In contrast, the
latter, apparently diverse galaxies or galaxy components have almost identical
parameter correlations. This shows that they are related. A review of galaxy
transformation processes suggests that S0 and spheroidal galaxies are
star-formation-quenched, "red and dead" versions of spiral and Im galaxies. In
particular, Sph galaxies are bulgeless S0s. This motivates a parallel sequence
galaxy classification in which an S0a-S0b-S0c-Sph sequence of decreasing
bulge-to-total ratios is juxtaposed to an Sa-Sb-Sc-Im sequence of star-forming
galaxies. All parameter sequences show a complete continuity from giant
galaxies to the tiniest dwarfs. Dwarfs are not a new or different class of
galaxies. Rather, they are the extreme products of transformation processes
that get more important as gravitational potential wells get more shallow.
Smaller Sph and S+Im galaxies have lower stellar densities because they retain
fewer baryons. Comparison of the baryonic parameter correlations with those for
dark matter halos allows us to estimate baryon loss as a function of galaxy
mass. Extreme dwarfs are almost completely dominated by dark matter.Comment: 10 pages, 6 postscript figures, LaTeX using custom svmult.cls file,
  accepted for publication in Seychelles conference on galaxy evolution,
  "Lessons from the Local Group", ed. K. C. Freeman, B. G. Elmegreen, D. L.
  Block, and M. Woolway (Dordrecht: Springer), in press, 201
Lessons from the Local Group (and beyond) on dark matter

(Abridged) The existence of exotic dark matter particles outside the standard
model of particle physics constitutes a central hypothesis of the current
standard model of cosmology (SMoC). Using a wide range of observational data I
outline why this hypothesis cannot be correct for the real Universe. Assuming
the SMoC to hold, (i) the two types of dwarf galaxies, the primordial dwarfs
with dark matter and the tidal dwarf galaxies without dark matter, ought to
present clear observational differences. But there is no observational evidence
for two separate families of dwarfs, neither in terms of their location
relative to the baryonic Tully-Fisher relation nor in terms of their
radius--mass relation. And, the arrangements in rotating disk-of-satellites, in
particular around the Milky Way and Andromeda, has been found to be only
consistent with most if not all dwarf satellite galaxies being tidal dwarf
galaxies. The highly symmetric structure of the entire Local Group too is
inconsistent with its galaxies stemming from a stochastic merger-driven
hierarchical buildup over cosmic time. (ii) Dynamical friction on the expansive
and massive dark matter halos is not evident in the data. Taking the various
lines of evidence together, the hypothesis that dynamically relevant exotic
dark matter exists needs to be firmly rejected.Comment: 13 pages, 2 figures, invited presentation, accepted for publication
  in Seychelles conference on galaxy evolution, "Lessons from the Local Group",
  ed. K. C. Freeman, B. G. Elmegreen, D. L. Block, and M. Woolway (Dordrecht:
  Springer), in press, 201
The Planetary Nebulae Populations in the Local Group

Planetary nebulae have been used as tracers of light and kinematics for the
stellar populations in early-type galaxies since more than twenty years.
Several empirical properties have surfaced: for example the invariant bright
cut-off of the planetary nebulae luminosity function and correlations of the
luminosity specific PN number with the integrated properties of the parent
stellar populations. These observed properties are poorly understood in terms
of a simple model of a ionized nebula expanding around a non-evolving central
star. In order to make further steps, we need to study self-contained systems
at know distances whose PN populations are sufficiently nearby to permit
investigation into their physical properties. The galaxies in the Local Group
represent a valid proxies to study these late phases of evolved stellar
populations with a spread of metallicities, $\alpha$-element enhancements, and
star forming histories.Comment: 10 pages, 5 figures. To appear in "Lessons from the Local Group - A
  Conference in Honour of David Block and Bruce Elmegreen" (eds. Freeman, K.C.,
  Elmegreen, B.G., Block, D.L. \& Woolway, M., SPRINGER: NEW YORK