407 research outputs found
Markerless Motion Capture via Convolutional Neural Network
A human motion capture system can be defined as a process that digitally records the movements of a person and then translates them into computer-animated images.
To achieve this goal, motion capture systems usually exploit different types of algorithms, which include techniques such as pose estimation or background subtraction: this latter aims at segmenting moving objects from the background under multiple challenging scenarios. Recently, encoder-decoder-type deep neural networks designed to accomplish this task have reached impressive results, outperforming classical approaches.
The aim of this thesis is to evaluate and discuss the predictions provided by the multi-scale convolutional neural network FgSegNet_v2, a deep learning-based method which represents the current state-of-the-art for implementing scene-specific background subtraction.
In this work, FgSegNet_v2 is trained and tested on BBSoF S.r.l. dataset, extending its scene- specific use to a more general application in several environments
Risky Action Recognition in Lane Change Video Clips using Deep Spatiotemporal Networks with Segmentation Mask Transfer
Advanced driver assistance and automated driving systems rely on risk
estimation modules to predict and avoid dangerous situations. Current methods
use expensive sensor setups and complex processing pipeline, limiting their
availability and robustness. To address these issues, we introduce a novel deep
learning based action recognition framework for classifying dangerous lane
change behavior in short video clips captured by a monocular camera. We
designed a deep spatiotemporal classification network that uses pre-trained
state-of-the-art instance segmentation network Mask R-CNN as its spatial
feature extractor for this task. The Long-Short Term Memory (LSTM) and
shallower final classification layers of the proposed method were trained on a
semi-naturalistic lane change dataset with annotated risk labels. A
comprehensive comparison of state-of-the-art feature extractors was carried out
to find the best network layout and training strategy. The best result, with a
0.937 AUC score, was obtained with the proposed network. Our code and trained
models are available open-source.Comment: 8 pages, 3 figures, 1 table. The code is open-sourc
Reliable Navigational Scene Perception for Autonomous Ships in Maritime Environment
Due to significant advances in robotics and transportation, research on autonomous
ships has attracted considerable attention. The most critical task is to make the
ships capable of accurately, reliably, and intelligently detecting their surroundings
to achieve high levels of autonomy. Three deep learning-based models are constructed
in this thesis to perform complex perceptual tasks such as identifying ships,
analysing encounter situations, and recognising water surface objects. In this thesis,
sensors, including the Automatic Identification System (AIS) and cameras, provide
critical information for scene perception. Specifically, the AIS enables mid-range
and long-range detection, assisting the decision-making system to take suitable and
decisive action. A Convolutional Neural Network-Ship Movement Modes Classification
(CNN-SMMC) is used to detect ships or objects. Following that, a Semi-
Supervised Convolutional Encoder-Decoder Network (SCEDN) is developed to
classify ship encounter situations and make a collision avoidance plan for the moving
ships or objects. Additionally, cameras are used to detect short-range objects, a
supplementary solution to ships or objects not equipped with an AIS. A Water Obstacle
Detection Network based on Image Segmentation (WODIS) is developed to
find potential threat targets. A series of quantifiable experiments have demonstrated
that these models can provide reliable scene perception for autonomous ships
Safety of autonomous vehicles: A survey on Model-based vs. AI-based approaches
The growing advancements in Autonomous Vehicles (AVs) have emphasized the
critical need to prioritize the absolute safety of AV maneuvers, especially in
dynamic and unpredictable environments or situations. This objective becomes
even more challenging due to the uniqueness of every traffic
situation/condition. To cope with all these very constrained and complex
configurations, AVs must have appropriate control architectures with reliable
and real-time Risk Assessment and Management Strategies (RAMS). These targeted
RAMS must lead to reduce drastically the navigation risks. However, the lack of
safety guarantees proves, which is one of the key challenges to be addressed,
limit drastically the ambition to introduce more broadly AVs on our roads and
restrict the use of AVs to very limited use cases. Therefore, the focus and the
ambition of this paper is to survey research on autonomous vehicles while
focusing on the important topic of safety guarantee of AVs. For this purpose,
it is proposed to review research on relevant methods and concepts defining an
overall control architecture for AVs, with an emphasis on the safety assessment
and decision-making systems composing these architectures. Moreover, it is
intended through this reviewing process to highlight researches that use either
model-based methods or AI-based approaches. This is performed while emphasizing
the strengths and weaknesses of each methodology and investigating the research
that proposes a comprehensive multi-modal design that combines model-based and
AI approaches. This paper ends with discussions on the methods used to
guarantee the safety of AVs namely: safety verification techniques and the
standardization/generalization of safety frameworks
Attention Mechanism for Recognition in Computer Vision
It has been proven that humans do not focus their attention on an entire scene at once when they perform a recognition task. Instead, they pay attention to the most important parts of the scene to extract the most discriminative information. Inspired by this observation, in this dissertation, the importance of attention mechanism in recognition tasks in computer vision is studied by designing novel attention-based models. In specific, four scenarios are investigated that represent the most important aspects of attention mechanism.First, an attention-based model is designed to reduce the visual features\u27 dimensionality by selectively processing only a small subset of the data. We study this aspect of the attention mechanism in a framework based on object recognition in distributed camera networks. Second, an attention-based image retrieval system (i.e., person re-identification) is proposed which learns to focus on the most discriminative regions of the person\u27s image and process those regions with higher computation power using a deep convolutional neural network. Furthermore, we show how visualizing the attention maps can make deep neural networks more interpretable. In other words, by visualizing the attention maps we can observe the regions of the input image where the neural network relies on, in order to make a decision. Third, a model for estimating the importance of the objects in a scene based on a given task is proposed. More specifically, the proposed model estimates the importance of the road users that a driver (or an autonomous vehicle) should pay attention to in a driving scenario in order to have safe navigation. In this scenario, the attention estimation is the final output of the model. Fourth, an attention-based module and a new loss function in a meta-learning based few-shot learning system is proposed in order to incorporate the context of the task into the feature representations of the samples and increasing the few-shot recognition accuracy.In this dissertation, we showed that attention can be multi-facet and studied the attention mechanism from the perspectives of feature selection, reducing the computational cost, interpretable deep learning models, task-driven importance estimation, and context incorporation. Through the study of four scenarios, we further advanced the field of where \u27\u27attention is all you need\u27\u27
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