1,826 research outputs found
Hierarchical fusion of color and depth information at partition level by cooperative region merging
A high level scheme for information fusion to create hierarchical
region-based image representations based on a region merging process
is presented. The strategy is based on an iterative evolution
where the different merging criteria work independently and cooperate
at the partition level to obtain a further consensus that increases
the reliability of the resulting partitions. This cooperative scheme is
applied to the creation of hierarchical region-based representations
of the image based on color and depth information. The proposed
technique is compared with approaches using only one source of information
or linear combinations of both, in datasets with ground
truth as well as estimated disparity information.Postprint (published version
Joint segmentation of color and depth data based on splitting and merging driven by surface fitting
This paper proposes a segmentation scheme based on the joint usage of color and depth data together with a 3D surface estimation scheme. Firstly a set of multi-dimensional vectors is built from color, geometry and surface orientation information. Normalized cuts spectral clustering is then applied in order to recursively segment the scene in two parts thus obtaining an over-segmentation. This procedure is followed by a recursive merging stage where close segments belonging to the same object are joined together. At each step of both procedures a NURBS model is fitted on the computed segments and the accuracy of the fitting is used as a measure of the plausibility that a segment represents a single surface or object. By comparing the accuracy to the one at the previous step, it is possible to determine if each splitting or merging operation leads to a better scene representation and consequently whether to perform it or not. Experimental results show how the proposed method provides an accurate and reliable segmentation
Joint segmentation of color and depth data based on splitting and merging driven by surface fitting
This paper proposes a segmentation scheme based on the joint usage of color and depth data together with a 3D surface estimation scheme. Firstly a set of multi-dimensional vectors is built from color, geometry and surface orientation information. Normalized cuts spectral clustering is then applied in order to recursively segment the scene in two parts thus obtaining an over-segmentation. This procedure is followed by a recursive merging stage where close segments belonging to the same object are joined together. At each step of both procedures a NURBS model is fitted on the computed segments and the accuracy of the fitting is used as a measure of the plausibility that a segment represents a single surface or object. By comparing the accuracy to the one at the previous step, it is possible to determine if each splitting or merging operation leads to a better scene representation and consequently whether to perform it or not. Experimental results show how the proposed method provides an accurate and reliable segmentation
Enabling Neural Radiance Fields (NeRF) for Large-scale Aerial Images -- A Multi-tiling Approach and the Geometry Assessment of NeRF
Neural Radiance Fields (NeRF) offer the potential to benefit 3D
reconstruction tasks, including aerial photogrammetry. However, the scalability
and accuracy of the inferred geometry are not well-documented for large-scale
aerial assets,since such datasets usually result in very high memory
consumption and slow convergence.. In this paper, we aim to scale the NeRF on
large-scael aerial datasets and provide a thorough geometry assessment of NeRF.
Specifically, we introduce a location-specific sampling technique as well as a
multi-camera tiling (MCT) strategy to reduce memory consumption during image
loading for RAM, representation training for GPU memory, and increase the
convergence rate within tiles. MCT decomposes a large-frame image into multiple
tiled images with different camera models, allowing these small-frame images to
be fed into the training process as needed for specific locations without a
loss of accuracy. We implement our method on a representative approach,
Mip-NeRF, and compare its geometry performance with threephotgrammetric MVS
pipelines on two typical aerial datasets against LiDAR reference data. Both
qualitative and quantitative results suggest that the proposed NeRF approach
produces better completeness and object details than traditional approaches,
although as of now, it still falls short in terms of accuracy.Comment: 9 Figur
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Knowledge Discovery and Data Mining for Shared Mobility and Connected and Automated Vehicle Applications
The rapid development of shared mobility and connected and automated vehicles (CAVs) has not only brought new intelligent transportation system (ITS) challenges with the new types of mobility, but also brought a huge opportunity to accelerate the connectivity and informatization of transportation systems, particularly when we consider all the new forms of data that is becoming available. The primary challenge is how to take advantage of the enormous amount of data to discover knowledge, build effective models, and develop impactful applications. With the theoretical and experimental progress being made over the last two decades, data mining and machine learning technologies have become key approaches for parsing data, understanding information, and making informed decisions, especially as the rise of deep learning algorithms bringing new levels of performance to the analysis of large datasets. The combination of data mining and ITS can greatly benefit research and advances in shared mobility and CAVs.This dissertation focuses on knowledge discovery and data mining for shared mobility and CAV applications. When considering big data associated with shared mobility operations and CAV research, data mining techniques can be customized with transportation knowledge to initially parse the data. Then machine learning methods can be used to model the parsed data to elicit hidden knowledge. Finally, the discovered knowledge and extracted information can help in the development of effective shared mobility and CAV applications to achieve the goals of a safer, faster, and more eco-friendly transportation systems.In this dissertation, there are four main sections that are addressed. First, new methodologies are introduced for extracting lane-level road features from rough crowdsourced GPS trajectories via data mining, which is subsequently used as the fundamental information for CAV applications. The proposed method results in decimeter level accuracy, which satisfies the positioning needs for many macroscopic and microscopic shared mobility and CAV applications. Second, macroscopic ride-hailing service big data has been analyzed for demand prediction, vehicle operation, and system efficiency monitoring. The proposed deep learning algorithms increase the ride-hailing demand prediction accuracy to 80% and can help the fleet dispatching system reduce 30% of vacant travel distance. Third, microscopic automated vehicle perception data has been analyzed for a real-time computer vision system that can be used for lane change behavior detection. The proposed deep learning design combines the residual neural network image input with time serious control data and reaches 95% of lane change behavior prediction accuracy. Last but not least, new ride sharing and CAV applications have been simulated in a behavior modeling framework to analyze the impact of mobility and energy consumption, which addresses key barriers by quantifying the transportation system-wide mobility, energy and behavior impacts from new mobility technologies using real-world data
Color and depth based image segmentation using a game-theoretic approach
In this thesis a new game theoretic approach to image segmentation is proposed.
It is an attempt to give a contribution to a new interesting research area in image processing, which tries to boost image segmentation combining information about appareance (e.g. color) and information about spatial arrangement.
The proposed algorithm firstly partition the image into small subsets of pixels, in order to reduce computational complexity of the subsequent phases. Two different distance measures between each pair of pixels subsets are then computed, one regarding color information and one based on spatial-geometric information. A similarity measure between each pair of pixel subset is then computed, exploiting both color and spatial data. Finally, pixels subsets are modeled into an evolutionary game in order to group similar pixels into meaningful segments.
After a brief review of image segmentation approaches, the proposed algorithm is described and different experimental tests are carried up to evaluate its segmentation performanc
Gunrock: GPU Graph Analytics
For large-scale graph analytics on the GPU, the irregularity of data access
and control flow, and the complexity of programming GPUs, have presented two
significant challenges to developing a programmable high-performance graph
library. "Gunrock", our graph-processing system designed specifically for the
GPU, uses a high-level, bulk-synchronous, data-centric abstraction focused on
operations on a vertex or edge frontier. Gunrock achieves a balance between
performance and expressiveness by coupling high performance GPU computing
primitives and optimization strategies with a high-level programming model that
allows programmers to quickly develop new graph primitives with small code size
and minimal GPU programming knowledge. We characterize the performance of
various optimization strategies and evaluate Gunrock's overall performance on
different GPU architectures on a wide range of graph primitives that span from
traversal-based algorithms and ranking algorithms, to triangle counting and
bipartite-graph-based algorithms. The results show that on a single GPU,
Gunrock has on average at least an order of magnitude speedup over Boost and
PowerGraph, comparable performance to the fastest GPU hardwired primitives and
CPU shared-memory graph libraries such as Ligra and Galois, and better
performance than any other GPU high-level graph library.Comment: 52 pages, invited paper to ACM Transactions on Parallel Computing
(TOPC), an extended version of PPoPP'16 paper "Gunrock: A High-Performance
Graph Processing Library on the GPU
A Novel Driver Distraction Behavior Detection Based on Self-Supervised Learning Framework with Masked Image Modeling
Driver distraction causes a significant number of traffic accidents every
year, resulting in economic losses and casualties. Currently, the level of
automation in commercial vehicles is far from completely unmanned, and drivers
still play an important role in operating and controlling the vehicle.
Therefore, driver distraction behavior detection is crucial for road safety. At
present, driver distraction detection primarily relies on traditional
Convolutional Neural Networks (CNN) and supervised learning methods. However,
there are still challenges such as the high cost of labeled datasets, limited
ability to capture high-level semantic information, and weak generalization
performance. In order to solve these problems, this paper proposes a new
self-supervised learning method based on masked image modeling for driver
distraction behavior detection. Firstly, a self-supervised learning framework
for masked image modeling (MIM) is introduced to solve the serious human and
material consumption issues caused by dataset labeling. Secondly, the Swin
Transformer is employed as an encoder. Performance is enhanced by reconfiguring
the Swin Transformer block and adjusting the distribution of the number of
window multi-head self-attention (W-MSA) and shifted window multi-head
self-attention (SW-MSA) detection heads across all stages, which leads to model
more lightening. Finally, various data augmentation strategies are used along
with the best random masking strategy to strengthen the model's recognition and
generalization ability. Test results on a large-scale driver distraction
behavior dataset show that the self-supervised learning method proposed in this
paper achieves an accuracy of 99.60%, approximating the excellent performance
of advanced supervised learning methods
Deep Learning for Decision Making and Autonomous Complex Systems
Deep learning consists of various machine learning algorithms that aim to learn multiple levels of abstraction from data in a hierarchical manner. It is a tool to construct models using the data that mimics a real world process without an exceedingly tedious modelling of the actual process. We show that deep learning is a viable solution to decision making in mechanical engineering problems and complex physical systems.
In this work, we demonstrated the application of this data-driven method in the design of microfluidic devices to serve as a map between the user-defined cross-sectional shape of the flow and the corresponding arrangement of micropillars in the flow channel that contributed to the flow deformation. We also present how deep learning can be used in the early detection of combustion instability for prognostics and health monitoring of a combustion engine, such that appropriate measures can be taken to prevent detrimental effects as a result of unstable combustion.
One of the applications in complex systems concerns robotic path planning via the systematic learning of policies and associated rewards. In this context, a deep architecture is implemented to infer the expected value of information gained by performing an action based on the states of the environment. We also applied deep learning-based methods to enhance natural low-light images in the context of a surveillance framework and autonomous robots. Further, we looked at how machine learning methods can be used to perform root-cause analysis in cyber-physical systems subjected to a wide variety of operation anomalies. In all studies, the proposed frameworks have been shown to demonstrate promising feasibility and provided credible results for large-scale implementation in the industry
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