11,159 research outputs found
Perceptually Motivated Shape Context Which Uses Shape Interiors
In this paper, we identify some of the limitations of current-day shape
matching techniques. We provide examples of how contour-based shape matching
techniques cannot provide a good match for certain visually similar shapes. To
overcome this limitation, we propose a perceptually motivated variant of the
well-known shape context descriptor. We identify that the interior properties
of the shape play an important role in object recognition and develop a
descriptor that captures these interior properties. We show that our method can
easily be augmented with any other shape matching algorithm. We also show from
our experiments that the use of our descriptor can significantly improve the
retrieval rates
HD-Index: Pushing the Scalability-Accuracy Boundary for Approximate kNN Search in High-Dimensional Spaces
Nearest neighbor searching of large databases in high-dimensional spaces is
inherently difficult due to the curse of dimensionality. A flavor of
approximation is, therefore, necessary to practically solve the problem of
nearest neighbor search. In this paper, we propose a novel yet simple indexing
scheme, HD-Index, to solve the problem of approximate k-nearest neighbor
queries in massive high-dimensional databases. HD-Index consists of a set of
novel hierarchical structures called RDB-trees built on Hilbert keys of
database objects. The leaves of the RDB-trees store distances of database
objects to reference objects, thereby allowing efficient pruning using distance
filters. In addition to triangular inequality, we also use Ptolemaic inequality
to produce better lower bounds. Experiments on massive (up to billion scale)
high-dimensional (up to 1000+) datasets show that HD-Index is effective,
efficient, and scalable.Comment: PVLDB 11(8):906-919, 201
Visual to Sound: Generating Natural Sound for Videos in the Wild
As two of the five traditional human senses (sight, hearing, taste, smell,
and touch), vision and sound are basic sources through which humans understand
the world. Often correlated during natural events, these two modalities combine
to jointly affect human perception. In this paper, we pose the task of
generating sound given visual input. Such capabilities could help enable
applications in virtual reality (generating sound for virtual scenes
automatically) or provide additional accessibility to images or videos for
people with visual impairments. As a first step in this direction, we apply
learning-based methods to generate raw waveform samples given input video
frames. We evaluate our models on a dataset of videos containing a variety of
sounds (such as ambient sounds and sounds from people/animals). Our experiments
show that the generated sounds are fairly realistic and have good temporal
synchronization with the visual inputs.Comment: Project page:
http://bvision11.cs.unc.edu/bigpen/yipin/visual2sound_webpage/visual2sound.htm
Visual Landmark Recognition from Internet Photo Collections: A Large-Scale Evaluation
The task of a visual landmark recognition system is to identify photographed
buildings or objects in query photos and to provide the user with relevant
information on them. With their increasing coverage of the world's landmark
buildings and objects, Internet photo collections are now being used as a
source for building such systems in a fully automatic fashion. This process
typically consists of three steps: clustering large amounts of images by the
objects they depict; determining object names from user-provided tags; and
building a robust, compact, and efficient recognition index. To this date,
however, there is little empirical information on how well current approaches
for those steps perform in a large-scale open-set mining and recognition task.
Furthermore, there is little empirical information on how recognition
performance varies for different types of landmark objects and where there is
still potential for improvement. With this paper, we intend to fill these gaps.
Using a dataset of 500k images from Paris, we analyze each component of the
landmark recognition pipeline in order to answer the following questions: How
many and what kinds of objects can be discovered automatically? How can we best
use the resulting image clusters to recognize the object in a query? How can
the object be efficiently represented in memory for recognition? How reliably
can semantic information be extracted? And finally: What are the limiting
factors in the resulting pipeline from query to semantics? We evaluate how
different choices of methods and parameters for the individual pipeline steps
affect overall system performance and examine their effects for different query
categories such as buildings, paintings or sculptures
Coherent Diffraction Imaging of Single 95nm Nanowires
Photonic or electronic confinement effects in nanostructures become
significant when one of their dimension is in the 5-300 nm range. Improving
their development requires the ability to study their structure - shape, strain
field, interdiffusion maps - using novel techniques. We have used coherent
diffraction imaging to record the 3-dimensionnal scattered intensity of single
silicon nanowires with a lateral size smaller than 100 nm. We show that this
intensity can be used to recover the hexagonal shape of the nanowire with a
28nm resolution. The article also discusses limits of the method in terms of
radiation damage.Comment: 5 pages, 5 figure
Siamese Instance Search for Tracking
In this paper we present a tracker, which is radically different from
state-of-the-art trackers: we apply no model updating, no occlusion detection,
no combination of trackers, no geometric matching, and still deliver
state-of-the-art tracking performance, as demonstrated on the popular online
tracking benchmark (OTB) and six very challenging YouTube videos. The presented
tracker simply matches the initial patch of the target in the first frame with
candidates in a new frame and returns the most similar patch by a learned
matching function. The strength of the matching function comes from being
extensively trained generically, i.e., without any data of the target, using a
Siamese deep neural network, which we design for tracking. Once learned, the
matching function is used as is, without any adapting, to track previously
unseen targets. It turns out that the learned matching function is so powerful
that a simple tracker built upon it, coined Siamese INstance search Tracker,
SINT, which only uses the original observation of the target from the first
frame, suffices to reach state-of-the-art performance. Further, we show the
proposed tracker even allows for target re-identification after the target was
absent for a complete video shot.Comment: This paper is accepted to the IEEE Conference on Computer Vision and
Pattern Recognition, 201
Information system for image classification based on frequency curve proximity
With the size digital collections are currently reaching, retrieving the best match of a
document from large collections by comparing hundreds of tags is a task that involves
considerable algorithm complexity, even more so if the number of tags in the collection is
not fixed. For these cases, similarity search appears to be the best retrieval method, but
there is a lack of techniques suited for these conditions. This work presents a combination
of machine learning algorithms put together to find the most similar object of a given one
in a set of pre-processed objects based only on their metadata tags. The algorithm
represents objects as character frequency curves and is capable of finding relationships
between objects without an apparent association. It can also be parallelized using
MapReduce strategies to perform the search. This method can be applied to a wide variety
of documents with metadata tags. The case-study used in this work to demonstrate the
similarity search technique is that of a collection of image objects in JavaScript Object
Notation (JSON) containing metadata tags.This work has been done in the context of the project
“ASASEC (Advisory System Against Sexual Exploitation of
Children)” (HOME/2010/ISEC/AG/043) supported by the
European Union with the program “Prevention and fight
against crime”.info:eu-repo/semantics/publishedVersio
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