170 research outputs found
An accurate retrieval through R-MAC+ descriptors for landmark recognition
The landmark recognition problem is far from being solved, but with the use
of features extracted from intermediate layers of Convolutional Neural Networks
(CNNs), excellent results have been obtained. In this work, we propose some
improvements on the creation of R-MAC descriptors in order to make the
newly-proposed R-MAC+ descriptors more representative than the previous ones.
However, the main contribution of this paper is a novel retrieval technique,
that exploits the fine representativeness of the MAC descriptors of the
database images. Using this descriptors called "db regions" during the
retrieval stage, the performance is greatly improved. The proposed method is
tested on different public datasets: Oxford5k, Paris6k and Holidays. It
outperforms the state-of-the- art results on Holidays and reached excellent
results on Oxford5k and Paris6k, overcame only by approaches based on
fine-tuning strategies
A Dense-Depth Representation for VLAD descriptors in Content-Based Image Retrieval
The recent advances brought by deep learning allowed to improve the
performance in image retrieval tasks. Through the many convolutional layers,
available in a Convolutional Neural Network (CNN), it is possible to obtain a
hierarchy of features from the evaluated image. At every step, the patches
extracted are smaller than the previous levels and more representative.
Following this idea, this paper introduces a new detector applied on the
feature maps extracted from pre-trained CNN. Specifically, this approach lets
to increase the number of features in order to increase the performance of the
aggregation algorithms like the most famous and used VLAD embedding. The
proposed approach is tested on different public datasets: Holidays, Oxford5k,
Paris6k and UKB
Exploiting Deep Features for Remote Sensing Image Retrieval: A Systematic Investigation
Remote sensing (RS) image retrieval is of great significant for geological
information mining. Over the past two decades, a large amount of research on
this task has been carried out, which mainly focuses on the following three
core issues: feature extraction, similarity metric and relevance feedback. Due
to the complexity and multiformity of ground objects in high-resolution remote
sensing (HRRS) images, there is still room for improvement in the current
retrieval approaches. In this paper, we analyze the three core issues of RS
image retrieval and provide a comprehensive review on existing methods.
Furthermore, for the goal to advance the state-of-the-art in HRRS image
retrieval, we focus on the feature extraction issue and delve how to use
powerful deep representations to address this task. We conduct systematic
investigation on evaluating correlative factors that may affect the performance
of deep features. By optimizing each factor, we acquire remarkable retrieval
results on publicly available HRRS datasets. Finally, we explain the
experimental phenomenon in detail and draw conclusions according to our
analysis. Our work can serve as a guiding role for the research of
content-based RS image retrieval
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Deep Structured Multi-Task Learning for Computer Vision in Autonomous Driving
The field of computer vision is currently dominated by deep learning advances. Convolutional
Neural Networks (CNNs) have become the predominant tool for solving almost any computer
vision task, so state-of-the-art systems have been built by using the predictive capabilities of
Convolutional Neural Networks (CNNs). Many of those systems use simple encoder–decoder
based design, where an off-the-shelf CNN architecture is combined with a task-specific
decoder and loss function in order to create an end-to-end trainable model. This ultimately
raises the question of whether these kinds of models are the future of computer vision.
In this thesis we argue that this is not the case. We start off by discussing three limitations
of simple end-to-end training. We proceed by showing how it is possible to overcome those
limitations by using an approach that we call structured modelling. The idea is to use CNNs
to compute a rich semantic intermediate representation which is then used to solve the actual
problem by applying a geometric and task-related structure.
In this work we solve the localization, segmentation and landmark recognition task
using structured modelling, and we show that this approach can improve generalization,
interpretability and robustness. We also discuss how this approach is particularly useful
for real-time applications such as autonomous driving. Visual perception is a multi-module
problem that requires several different computer vision tasks to be solved. We discuss how,
by sharing computations, we can improve not only the inference speed but also the prediction
performance by using the structural relationship between the tasks. Lastly, we demonstrate
that structured modelling is able to achieve state-of-the-art performance, making it a very
relevant approach for solving current and future computer vision problems.Trinity College, ESPCR, Qualcom
No Spare Parts: Sharing Part Detectors for Image Categorization
This work aims for image categorization using a representation of distinctive
parts. Different from existing part-based work, we argue that parts are
naturally shared between image categories and should be modeled as such. We
motivate our approach with a quantitative and qualitative analysis by
backtracking where selected parts come from. Our analysis shows that in
addition to the category parts defining the class, the parts coming from the
background context and parts from other image categories improve categorization
performance. Part selection should not be done separately for each category,
but instead be shared and optimized over all categories. To incorporate part
sharing between categories, we present an algorithm based on AdaBoost to
jointly optimize part sharing and selection, as well as fusion with the global
image representation. We achieve results competitive to the state-of-the-art on
object, scene, and action categories, further improving over deep convolutional
neural networks
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