Optimal Radiometric Calibration for Camera-Display Communication

We present a novel method for communicating between a camera and display by embedding and recovering hidden and dynamic information within a displayed image. A handheld camera pointed at the display can receive not only the display image, but also the underlying message. These active scenes are fundamentally different from traditional passive scenes like QR codes because image formation is based on display emittance, not surface reflectance. Detecting and decoding the message requires careful photometric modeling for computational message recovery. Unlike standard watermarking and steganography methods that lie outside the domain of computer vision, our message recovery algorithm uses illumination to optically communicate hidden messages in real world scenes. The key innovation of our approach is an algorithm that performs simultaneous radiometric calibration and message recovery in one convex optimization problem. By modeling the photometry of the system using a camera-display transfer function (CDTF), we derive a physics-based kernel function for support vector machine classification. We demonstrate that our method of optimal online radiometric calibration (OORC) leads to an efficient and robust algorithm for computational messaging between nine commercial cameras and displays.Comment: 10 pages, Submitted to CVPR 201

Quartz sand surface morphology of granitic tafoni at Laoshan, China

43-48In this study, a SEM method was used to analyze the surface morphology of the quartz sand granitic tafoni at Laoshan, for the purpose of exploring the weathering process of this tafoni. Present study showed that granitic tafoni at Laoshan, the quartz sand roundness was dominated by angular and sub-angular morphologies. Massive Hydrodynamic features had been developed on the quartz sand surfaces, as well as wind and chemistry forms, which were more developed. It was determined that granitic tafoni at Laoshan, the quartz sand had suffered long-term rainy and windy mechanical erosion, as well as chemical dissolution from residual pit water. These findings differed from the earlier views that the tafone was formed by the glacial melt water

Phase messaging method for time-of-flight cameras

Ubiquitous light emitting devices and low-cost commercial digital cameras facilitate optical wireless communication system such as visual MIMO where handheld cameras communicate with electronic displays. While intensity-based optical communications are more prevalent in camera-display messaging, we present a novel method that uses modulated light phase for messaging and time-of-flight (ToF) cameras for receivers. With intensity-based methods, light signals can be degraded by reflections and ambient illumination. By comparison, communication using ToF cameras is more robust against challenging lighting conditions. Additionally, the concept of phase messaging can be combined with intensity messaging for a significant data rate advantage. In this work, we design and construct a phase messaging array (PMA), which is the first of its kind, to communicate to a ToF depth camera by manipulating the phase of the depth camera's infrared light signal. The array enables message variation spatially using a plane of infrared light emitting diodes and temporally by varying the induced phase shift. In this manner, the phase messaging array acts as the transmitter by electronically controlling the light signal phase. The ToF camera acts as the receiver by observing and recording a time-varying depth. We show a complete implementation of a 3×3 prototype array with custom hardware and demonstrating average bit accuracy as high as 97.8%. The prototype data rate with this approach is 1 Kbps that can be extended to approximately 10 Mbps.National Science Foundation (U.S.) (grant CNS-106546#

What learning strategies influence higher-order learning behaviours of medical students?

AbstractAims The aim of this study was to explore the relationship between the application of learning strategies and the emergence of higher-order learning behaviours among medical students in Chinese provincial undergraduate colleges, while also examining the impact of social demographic variables on the development of higher-order learning behaviours and learning strategy preferences.Methodology We conducted a relevant cross-sectional study using the Chinese College Student Survey (CCSS) online questionnaire to evaluate higher-order learning behaviours and learning strategies in medical undergraduate students attending provincial colleges in China. A total of 992 valid questionnaires were collected and analysed using SPSS 22.0 (SPSS Inc., Chicago, IL). We performed statistical analysis using one-sample t-tests to compare the results with the national norm score for medical subjects in undergraduate colleges. We also conducted variance analysis and regression analysis.Results The study found that the average scores for higher-order learning behaviours, enquiry-based learning and receptive learning behaviour among medical undergraduate students in provincial colleges were higher than the national norm score for medical subjects, indicating a positive trend. However, the average scores for other indicators were lower than the national norm score. The utilization of learning strategies and the development of higher-order learning behaviours among students were affected by various factors such as grade and gender. The study suggests that the preference for certain learning strategies, such as enquiry-based, receptive, integrative and collaborative, can have a significant impact on the emergence of higher-order learning behaviours.Conclusions The study has demonstrated a positive correlation between the utilization of learning strategies and the development of higher-order learning behaviours. This relationship has been observed in medical students attending provincial undergraduate colleges, where the adoption of enquiry-based, receptive, integrative and collaborative learning strategies has been found to significantly influence the emergence of higher-order learning behaviours.KEY MESSAGESThe implementation of learning strategies among medical students in provincial undergraduate colleges in China has a significant impact on high-level learning behaviours.The impact of high-level learning behaviours is reliant on comprehensive support from four distinct learning strategies: receptive learning, inquiry-based learning, comprehensive learning and collaborative learning.One of the most impactful learning strategies is receptive learning, particularly on high-order learning behaviours. On the other hand, reflective learning does not seem to have a significant effect.Changes in grades can significantly impact higher-order learning behaviours and affect the propensity for reflective and collaborative learning strategies.Females generally exhibit a greater preference for receptive learning strategies, while males tend to exhibit a greater preference for inquiry-based learning strategie

Memory-efficient Segmentation of High-resolution Volumetric MicroCT Images

In recent years, 3D convolutional neural networks have become the dominant approach for volumetric medical image segmentation. However, compared to their 2D counterparts, 3D networks introduce substantially more training parameters and higher requirement for the GPU memory. This has become a major limiting factor for designing and training 3D networks for high-resolution volumetric images. In this work, we propose a novel memory-efficient network architecture for 3D high-resolution image segmentation. The network incorporates both global and local features via a two-stage U-net-based cascaded framework and at the first stage, a memory-efficient U-net (meU-net) is developed. The features learnt at the two stages are connected via post-concatenation, which further improves the information flow. The proposed segmentation method is evaluated on an ultra high-resolution microCT dataset with typically 250 million voxels per volume. Experiments show that it outperforms state-of-the-art 3D segmentation methods in terms of both segmentation accuracy and memory efficiency.Comment: The paper is accepted to MIDL 2022. The codes are available at https://github.com/Virgil3706/Memory-efficient-U-ne

Distributed Optimization of Joint Seaport-All-Electric-Ships System under Polymorphic Network

As a result of the trend towards auto intelligence and greening of vehicles and with the concept of polymorphic network being put forward, the power transmission mode between seaports and all-electric ships (AESs) is likely to be converted to “peer-to-peer” transmission. According to practical shore power systems and carbon trade mechanisms, an advanced peer-to-peer power dispatching model-joint seaport-AESs microgrid(MG) system has been proposed in the paper. The joint seaport–AES system model is proposed to minimize the total operational cost of power production and marketing, including distributed generation (DG) cost, electricity trading cost, and carbon emissions, and the boundary conditions are given as well. A parameter projection distributed optimization (PPDO) algorithm is utilized to solve the distributed optimization power operation planning of the proposed joint seaport–AES MG system under a polymorphic network and to guarantee the precision of power dispatching, which compensates for the insufficiency of the computing power. Finally, a case study of a five-node polymorphic joint seaport-AESs system is conducted. The feasibility of the parameter projection approach and the peer-to-peer power dispatching model are verified via the convergence of all the agents within the constraint sets

Dynamic and Invisible Messaging for Visual MIMO

The growing ubiquity of cameras in hand-held devices and the prevalence of electronic displays in signage creates a novel framework for wireless communications. Traditionally, the term MIMO is used for multiple-input multipleoutput where the multiple-input component is a set of radio transmitters and the multiple-output component is a set of radio receivers. We employ the concept of visual MIMO where pixels are transmitters and cameras are receivers. In this manner, the techniques of computer vision can be combined with principles from wireless communications to create an optical line-of-sight communications channel. Two major challenges are addressed: (1) The message for transmission must be embedded in the observed display so that the message is hidden from the observer and the electronic display can simultaneously be used for its originally intended purpose (e.g. signage, advertisements, maps); (2) Photometric and geometric distortions during the imaging process corrupt the information channel between the transmitter display and the receiver camera. These distortions must be modeled and removed. In this paper, we present a real-time messaging paradigm and its implementation in an operational visual MIMO optical systems. As part of the system, we develop a novel algorithm for photographic message extraction which includes automatic display detection, message embedding and message retrieval. Experiments show that the system achieves an average accuracy of 94.6 % at the bitrate of 6222.2 bps. 1

MATRIX FACTORIZATION FOR FAST DCT ALGORITHMS

Two principles to produce new possibilities for the radix-2 Discrete Cosine Transform (DCT) have been presented in this paper. One is to employ matrix factorization through revealing the intrinsic relationship among several existing famous algorithms, which is regarded as an effective guide for exploring new algorithms. The other is to make use of the orthogonal property of the DCT matrix. As long as the recursive kernel of an algorithm is orthogonal, there must be a twin fast DCT algorithm of it. Matrix factorization is applied through the research and can be used to show how data flows and compute the computational complexity easily. At the end of this paper, we also present a new fast algorithm for DCT. It enjoys the parallel structure which is simpler for programming and hardware implementation and keeps the same numbers of the additions and multiplications as the fastest algorithms. 1