Edge Video Analytics: A Survey on Applications, Systems and Enabling Techniques

Video, as a key driver in the global explosion of digital information, can create tremendous benefits for human society. Governments and enterprises are deploying innumerable cameras for a variety of applications, e.g., law enforcement, emergency management, traffic control, and security surveillance, all facilitated by video analytics (VA). This trend is spurred by the rapid advancement of deep learning (DL), which enables more precise models for object classification, detection, and tracking. Meanwhile, with the proliferation of Internet-connected devices, massive amounts of data are generated daily, overwhelming the cloud. Edge computing, an emerging paradigm that moves workloads and services from the network core to the network edge, has been widely recognized as a promising solution. The resulting new intersection, edge video analytics (EVA), begins to attract widespread attention. Nevertheless, only a few loosely-related surveys exist on this topic. The basic concepts of EVA (e.g., definition, architectures) were not fully elucidated due to the rapid development of this domain. To fill these gaps, we provide a comprehensive survey of the recent efforts on EVA. In this paper, we first review the fundamentals of edge computing, followed by an overview of VA. The EVA system and its enabling techniques are discussed next. In addition, we introduce prevalent frameworks and datasets to aid future researchers in the development of EVA systems. Finally, we discuss existing challenges and foresee future research directions. We believe this survey will help readers comprehend the relationship between VA and edge computing, and spark new ideas on EVA.Comment: 31 pages, 13 figure

Addressing concerns in performance prediction : the impact of data dependencies and denormal arithmetic in scientific codes

To meet the increasing computational requirements of the scientific community, the use of parallel programming has become commonplace, and in recent years distributed applications running on clusters of computers have become the norm. Both parallel and distributed applications face the problem of predictive uncertainty and variations in runtime. Modern scientific applications have varying I/O, cache, and memory profiles that have significant and difficult to predict effects on their runtimes. Data-dependent sensitivities such as the costs of denormal floating point calculations introduce more variations in runtime, further hindering predictability. Applications with unpredictable performance or which have highly variable runtimes can cause several problems. If the runtime of an application is unknown or varies widely, workflow schedulers cannot e�ciently allocate them to compute nodes, leading to the under-utilisation of expensive resources. Similarly, a lack of accurate knowledge of the performance of an application on new hardware can lead to misguided procurement decisions. In heavily parallel applications, minor variations in runtime on individual nodes can have disproportionate effects on the overall application runtime. Even on a smaller scale, a lack of certainty about an application's runtime can preclude its use in real-time or time-critical applications such as clinical diagnosis. This thesis investigates two sources of data-dependent performance variability. The first source is algorithmic and is seen in a state-of-the-art C++ biomedical imaging application. It identifies the cause of the variability in the application and develops a means of characterising the variability. This 'probe task' based model is adapted for use with a workflow scheduler, and the scheduling improvements it brings are examined. The second source of variability is more subtle as it is micro-architectural in nature. Depending on the input data, two runs of an application executing exactly the same sequence of instructions and with exactly the same memory access patterns can have large differences in runtime due to deficiencies in common hardware implementations of denormal arithmetic1. An exception-based profiler is written to detect occurrences of denormal arithmetic and it is shown how this is insufficient to isolate the sources of denormal arithmetic in an application. A novel tool based on theValgrind binary instrumentation framework is developed which can trace the origins of denormal values and the frequency of their occurrence in an application's data structures. This second tool is used to isolate and remove the cause of denormal arithmetic both from a simple numerical code, and then from a face recognition application

Tiny Machine Learning Environment: Enabling Intelligence on Constrained Devices

Running machine learning algorithms (ML) on constrained devices at the extreme edge of the network is problematic due to the computational overhead of ML algorithms, available resources on the embedded platform, and application budget (i.e., real-time requirements, power constraints, etc.). This required the development of specific solutions and development tools for what is now referred to as TinyML. In this dissertation, we focus on improving the deployment and performance of TinyML applications, taking into consideration the aforementioned challenges, especially memory requirements. This dissertation contributed to the construction of the Edge Learning Machine environment (ELM), a platform-independent open-source framework that provides three main TinyML services, namely shallow ML, self-supervised ML, and binary deep learning on constrained devices. In this context, this work includes the following steps, which are reflected in the thesis structure. First, we present the performance analysis of state-of-the-art shallow ML algorithms including dense neural networks, implemented on mainstream microcontrollers. The comprehensive analysis in terms of algorithms, hardware platforms, datasets, preprocessing techniques, and configurations shows similar performance results compared to a desktop machine and highlights the impact of these factors on overall performance. Second, despite the assumption that TinyML only permits models inference provided by the scarcity of resources, we have gone a step further and enabled self-supervised on-device training on microcontrollers and tiny IoT devices by developing the Autonomous Edge Pipeline (AEP) system. AEP achieves comparable accuracy compared to the typical TinyML paradigm, i.e., models trained on resource-abundant devices and then deployed on microcontrollers. Next, we present the development of a memory allocation strategy for convolutional neural networks (CNNs) layers, that optimizes memory requirements. This approach reduces the memory footprint without affecting accuracy nor latency. Moreover, e-skin systems share the main requirements of the TinyML fields: enabling intelligence with low memory, low power consumption, and low latency. Therefore, we designed an efficient Tiny CNN architecture for e-skin applications. The architecture leverages the memory allocation strategy presented earlier and provides better performance than existing solutions. A major contribution of the thesis is given by CBin-NN, a library of functions for implementing extremely efficient binary neural networks on constrained devices. The library outperforms state of the art NN deployment solutions by drastically reducing memory footprint and inference latency. All the solutions proposed in this thesis have been implemented on representative devices and tested in relevant applications, of which results are reported and discussed. The ELM framework is open source, and this work is clearly becoming a useful, versatile toolkit for the IoT and TinyML research and development community

Addressing concerns in performance prediction : the impact of data dependencies and denormal arithmetic in scientific codes

To meet the increasing computational requirements of the scientific community, the use of parallel programming has become commonplace, and in recent years distributed applications running on clusters of computers have become the norm. Both parallel and distributed applications face the problem of predictive uncertainty and variations in runtime. Modern scientific applications have varying I/O, cache, and memory profiles that have significant and difficult to predict effects on their runtimes. Data-dependent sensitivities such as the costs of denormal floating point calculations introduce more variations in runtime, further hindering predictability. Applications with unpredictable performance or which have highly variable runtimes can cause several problems. If the runtime of an application is unknown or varies widely, workflow schedulers cannot e�ciently allocate them to compute nodes, leading to the under-utilisation of expensive resources. Similarly, a lack of accurate knowledge of the performance of an application on new hardware can lead to misguided procurement decisions. In heavily parallel applications, minor variations in runtime on individual nodes can have disproportionate effects on the overall application runtime. Even on a smaller scale, a lack of certainty about an application’s runtime can preclude its use in real-time or time-critical applications such as clinical diagnosis. This thesis investigates two sources of data-dependent performance variability. The first source is algorithmic and is seen in a state-of-the-art C++ biomedical imaging application. It identifies the cause of the variability in the application and develops a means of characterising the variability. This ‘probe task’ based model is adapted for use with a workflow scheduler, and the scheduling improvements it brings are examined. The second source of variability is more subtle as it is micro-architectural in nature. Depending on the input data, two runs of an application executing exactly the same sequence of instructions and with exactly the same memory access patterns can have large differences in runtime due to deficiencies in common hardware implementations of denormal arithmetic1. An exception-based profiler is written to detect occurrences of denormal arithmetic and it is shown how this is insufficient to isolate the sources of denormal arithmetic in an application. A novel tool based on theValgrind binary instrumentation framework is developed which can trace the origins of denormal values and the frequency of their occurrence in an application’s data structures. This second tool is used to isolate and remove the cause of denormal arithmetic both from a simple numerical code, and then from a face recognition application.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Harnessing Big Data and Machine Learning for Event Detection and Localization

Anomalous events are rare and significantly deviate from expected pattern and other data instances, making them hard to predict. Correctly and timely detecting anomalous severe events can help reduce risks and losses. Many anomalous event detection techniques are studied in the literature. Recently, big data and machine learning based techniques have shown a remarkable success in a wide range of fields. It is important to tailor big data and machine learning based techniques for each application; otherwise it may result in expensive computation, slow prediction, false alarms, and improper prediction granularity.First, we aim to address the above challenges by harnessing big data and machine learning techniques for fast and reliable prediction and localization of severe events. Firstly, to improve storage failure prediction, we develop a new lightweight and high performing tensor decomposition-based method, named SEFEE, for storage error forecasting in large-scale enterprise storage systems. SEFEE employs tensor decomposition technique to capture latent spatio-temporal information embedded in storage event logs. By utilizing the latent spatio-temporal information, we can make accurate storage error forecasting without training requirements of typical machine learning techniques. The training-free method allows for live prediction of storage errors and their locations in the storage system based on previous observations that had been used in tensor decomposition pipeline to extract meaningful latent correlations. Moreover, we propose an extension to include severity of the errors as contextual information to improve the accuracy of tensor decomposition which in turn improves the prediction accuracy. We further provide detailed characterization of NetApp dataset to provide additional insight into the dynamics of typical large-scale enterprise storage systems for the community.Next, we focus on another application -- AI-driven Wildfire prediction. Wildfires cause billions of dollars in property damages and loss of lives, with harmful health threats. We aim to correctly detect and localize wildfire events in the early stage and also classify wildfire smoke based on perceived pixel density of camera images. Due to the lack of publicly available dataset for early wildfire smoke detection, we first collect and process images from the AlertWildfire camera network. The images are annotated with bounding boxes and densities for deep learning methods to use. We then adapt a transformer-based end-to-end object detection model for wildfire detection using our dataset. The dataset and detection model together form as a benchmark named the Nevada smoke detection benchmark, or Nemo for short. Nemo is the first open-source benchmark for wildfire smoke detection with the focus of the early incipient stage. We further provide a weakly supervised Nemo version to enable wider support as a benchmark

Tiny Machine Learning Environment: Enabling Intelligence on Constrained Devices

Running machine learning algorithms (ML) on constrained devices at the extreme edge of the network is problematic due to the computational overhead of ML algorithms, available resources on the embedded platform, and application budget (i.e., real-time requirements, power constraints, etc.). This required the development of specific solutions and development tools for what is now referred to as TinyML. In this dissertation, we focus on improving the deployment and performance of TinyML applications, taking into consideration the aforementioned challenges, especially memory requirements. This dissertation contributed to the construction of the Edge Learning Machine environment (ELM), a platform-independent open source framework that provides three main TinyML services, namely shallow ML, self-supervised ML, and binary deep learning on constrained devices. In this context, this work includes the following steps, which are reflected in the thesis structure. First, we present the performance analysis of state of the art shallow ML algorithms including dense neural networks, implemented on mainstream microcontrollers. The comprehensive analysis in terms of algorithms, hardware platforms, datasets, pre-processing techniques, and configurations shows similar performance results compared to a desktop machine and highlights the impact of these factors on overall performance. Second, despite the assumption that TinyML only permits models inference provided by the scarcity of resources, we have gone a step further and enabled self-supervised on-device training on microcontrollers and tiny IoT devices by developing the Autonomous Edge Pipeline (AEP) system. AEP achieves comparable accuracy compared to the typical TinyML paradigm, i.e., models trained on resource-abundant devices and then deployed on microcontrollers. Next, we present the development of a memory allocation strategy for convolutional neural networks (CNNs) layers, that optimizes memory requirements. This approach reduces the memory footprint without affecting accuracy nor latency. Moreover, e-skin systems share the main requirements of the TinyML fields: enabling intelligence with low memory, low power consumption, and low latency. Therefore, we designed an efficient Tiny CNN architecture for e-skin applications. The architecture leverages the memory allocation strategy presented earlier and provides better performance than existing solutions. A major contribution of the thesis is given by CBin-NN, a library of functions for implementing extremely efficient binary neural networks on constrained devices. The library outperforms state of the art NN deployment solutions by drastically reducing memory footprint and inference latency. All the solutions proposed in this thesis have been implemented on representative devices and tested in relevant applications, of which results are reported and discussed. The ELM framework is open source, and this work is clearly becoming a useful, versatile toolkit for the IoT and TinyML research and development community

Deep learning that scales: leveraging compute and data

Deep learning has revolutionized the field of artificial intelligence in the past decade. Although the development of these techniques spans over several years, the recent advent of deep learning is explained by an increased availability of data and compute that have unlocked the potential of deep neural networks. They have become ubiquitous in domains such as natural language processing, computer vision, speech processing, and control, where enough training data is available. Recent years have seen continuous progress driven by ever-growing neural networks that benefited from large amounts of data and computing power. This thesis is motivated by the observation that scale is one of the key factors driving progress in deep learning research, and aims at devising deep learning methods that scale gracefully with the available data and compute. We narrow down this scope into two main research directions. The first of them is concerned with designing hardware-aware methods which can make the most of the computing resources in current high performance computing facilities. We then study bottlenecks preventing existing methods from scaling up as more data becomes available, providing solutions that contribute towards enabling training of more complex models. This dissertation studies the aforementioned research questions for two different learning paradigms, each with its own algorithmic and computational characteristics. The first part of this thesis studies the paradigm where the model needs to learn from a collection of examples, extracting as much information as possible from the given data. The second part is concerned with training agents that learn by interacting with a simulated environment, which introduces unique challenges such as efficient exploration and simulation