We present Separated‑SLAM, a visual–inertial framework for effective indoor scene recognition and tracking. A new Atlas Evaluator thread evaluates the sparse indoor map for scene recognition and scene matching. For scene recognition, we preprocess sparse map points, project them onto three planes with a topology‑preserving intensity model, and encode the projections as compact histograms for fast matching. The matching results allow Separated‑SLAM to load the corresponding atlas from the database in real time while SLAM is running. After loop‑closure detection, the atlases are merged and the system switches to only‑tracking. During only‑tracking, ORB parameters are dynamically adjusted via the mode decision module to reduce the cost of feature extraction while preserving accuracy. Experiments on TUM‑VI show that Separated‑SLAM achieves accuracy comparable to ORB‑SLAM3 while reducing computation runtime by about 30% on average over complete trajectories; fine‑grained profiling further shows a 56.9% per‑frame reduction in the stabilized only‑tracking regime relative to full SLAM. The approach substantially lowers computational overhead when an atlas is available, streamlines sparse‑map matching, and provides a practical strategy to accelerate tracking after atlas merging.

Tactile sensing plays a crucial role in robot grasping and manipulation by providing essential contact information between the robot and the environment. In this paper, we present AllTact Fin Ray, a novel compliant gripper design with omni-directional and local tactile sensing capabilities. The finger body is unibody-casted using transparent elastic silicone, and a camera positioned at the base of the finger captures the deformation of the whole body and the contact face. Due to the global deformation of the adaptive structure, existing vision-based tactile sensing approaches that assume constant illumination are no longer applicable. To address this, we propose a novel sensing method where the global deformation is first reconstructed from the image using edge features and spatial constraints. Then, detailed contact geometry is computed from the brightness difference against a dynamically retrieved reference image. Extensive experiments validate the effectiveness of our proposed gripper design and sensing method in contact detection, force estimation, object grasping, and precise manipulation.

Reconstructing 3D human pose and body shape from monocular images or videos is a fundamental task for comprehending human dynamics. Frame-based methods can be broadly categorized into two fashions: those regressing parametric model parameters (e.g., SMPL) and those exploring alternative representations (e.g., volumetric shapes, 3D coordinates). Non-parametric representations have demonstrated superior performance due to their enhanced flexibility. However, when applied to video data, these non-parametric frame-based methods tend to generate inconsistent and unsmooth results. To this end, we present a novel approach that directly regresses the 3D coordinates of the mesh vertices and body joints with a spatial–temporal Transformer. In our method, we introduce a SpatioTemporal Learning Block (STLB) with Spatial Learning Module (SLM) and Temporal Learning Module (TLM), which leverages spatial and temporal information to model interactions at a finer granularity, specifically at the body token level. Our method outperforms previous state-of-the-art approaches on Human3.6M and 3DPW benchmark datasets.

Mobile edge computing (MEC) driven by 5G cellular systems has recently emerged as a promising paradigm, enabling mobile devices (MDs) with limited computing resources to offload various computation-intensive tasks (such as autopilot, online game) to edge servers to enhance the data processing capabilities of MDs. However, the uncertainty of wireless channel state and data volume of offloading tasks, as well as the data security privacy of offloading tasks, bring serious challenges to computation offloading in MEC. In this article, we consider a time-varying MEC scenario and formalize the delay and energy consumption during the computation offloading process as a joint optimization problem. Then the optimization problem is decomposed into two sub-problems: intelligent task prediction and resource allocation. Different from traditional methods, we improve the federated learning (FL) algorithm and propose a thoughtful cloud-edge-client FL task prediction mechanism based on Bidirectional Long Short-Term Memory. Each participating MD trains the model locally without uploading data to the server, and periodically aggregates the model in the edge and in the cloud. The algorithm both eliminates the need to solve complex optimization problems and ensures user privacy security. Finally, experimental results show that our proposed algorithm significantly outperforms other benchmark algorithms in energy efficiency.

UV-lamp driver especially for radiation at 253.7nm plays an important role in sewage treatment. In this paper, characteristics of the excitation of mercury atoms in the lamp are investigated deeply based on both theoretical knowledge on collision and experimental results on relationship between the irradiance at 253.7nm with the lamp power. An optimization design scheme is proposed to prolong the life span of the UV-lamp and enhance the irradiation of 253.7nm. The irradiance in each waveband emitted by the lamp is measured by illuminometers to validate the accuracy of the proposed optimization scheme. Experimental results verify the soundness of the theoretical analyses.

The parameters of the resistance model are obtained through various experiments under different lamp power in this study. Polynomial fitting curves are obtained for these parameters to get the values under some certain lamp power. Then simulations in PSIM are conducted by using the calculated values to verify the reliability and accuracy of the method adopted. Good agreement is obtained between the experimental results and simulation results. Finally, In order to improve the lifetime of the lamp and increase the UV irradiance at 253.7nm, the double capacitor topology is proposed and studied.

Compensation is a vital part in Inductively Coupled Power Transfer (ICPT) to achieve higher efficiency, power density and reliability. This article proposes two unilateral LC compensation topologies for ICPT system after thorough theoretical analysis, which achieve both zero-voltage switching and constant voltage output characteristics over a wide range of load. A 300W phase-shifted full bridge DC-DC Wireless Power Transfer device is designed and built which achieves an efficiency of 87.8% using proposed structure.

In compressive sensing (CS), a challenge is to find a space in which the signal is sparse and, hence, faithfully recoverable. Since many natural signals such as images have locally varying statistics, the sparse space varies in time/spatial domain. As such, CS recovery should be conducted in locally adaptive signal-dependent spaces to counter the fact that the CS measurements are global and irrespective of signal structures. On the contrary, existing CS reconstruction methods use a fixed set of bases (e.g., wavelets, DCT, and gradient spaces) for the entirety of a signal. To rectify this problem, we propose a new framework for model-guided adaptive recovery of compressive sensing (MARX) and show how a 2-D piecewise autoregressive model can be integrated into the MARX framework to make CS recovery adaptive to spatially varying second order statistics of an image. In addition, MARX offers a mechanism of characterizing and exploiting structured sparsities of natural images, greatly restricting the CS solution space. Simulation results over a wide range of natural images show that the proposed MARX technique can improve the reconstruction quality of existing CS methods by 2-7 dB.

In compressive sensing (CS) a challenge is to find a space in which the signal is sparse and hence recoverable faithfully and efficiently. Given the nonstationarity of many natural signals such as images, the sparse space varies in time/spatial domain. As such, CS recovery should be conducted in locally adaptive, signal-dependent spaces to counter the fact that the CS measurements are global and irrespective of signal structures. On the contrary most CS methods seek for a fixed set of bases (e.g., wavelets, DCT, and gradient spaces) for the entirety of a signal. To rectify this problem we propose a new framework for model-guided adaptive recovery of compressive sensing (MARX), and show how a piecewise autoregressive model can be integrated into the MARX framework to adapt to changing second order statistics of a signal in CS recovery. In addition, MARX offers a powerful mechanism of characterizing and exploiting structured sparsities of a signal, greatly restricting the CS solution space. A case study on CS-acquired images shows that the proposed MARX technique can increase the reconstruction quality by up to 8 dB over existing methods.

H.264 SVC extension, as the state of art scalable video coding standard, can offer a single code stream to serve diverse communication bandwidths and display resolutions. However, the rate-distortion performance of H.264 SVC is still inferior to the non-scalable H.264 AVC. To reduce the performance gap between H.264 SVC and H.264 AVC, we propose a model-based adaptive resolution upconversion algorithm to improve the precision of the H.264 SVC inter-layer prediction. The new algorithm treats the up-sampling of video frames as an inverse problem of initial H.264 SVC down-sampling operation, and it significantly improves the performance of current H.264 SVC by optimally reversing the down-sampling filter.

The problem of crosstalk between different color bands was seemingly overlooked by existing color demosaicking algorithms. In this paper we propose a new joint demosaicking and decrosstalk technique that corrects channel crosstalks by adaptive least-squares inverse filtering. The new technique integrates the operations of deconvolution for crosstalk removal and interpolation for color demosaicking, and it introduces a general framework in which any spatially varying crosstalks and varying spatial-spectral correlations can be modeled and factored into the color reproduction. Simulation results show that the proposed technique is highly effective and capable to obtain both high color fidelity and sharp, clean spatial details.

In interest of low cost, low power consumption, and compact size, most digital cameras adopt a design of single sensor array coupled with a color filter array. This design inevitably suffers, due to physical characteristics of the optical and semiconductor components and the imperfection of manufacturing, from the problem of crosstalk between different color channels. Channel crosstalk can desaturate colors and blur image details, but the problem was seemingly overlooked by existing color demosaicking algorithms. To rectify this deficiency we propose a new joint demosaicking and decrosstalk technique that counters the effects of channel crosstalks by adaptive least-squares inverse filtering. The new technique integrates the operations of deconvolution for crosstalk removal and interpolation for color demosaicking, and it introduces a general framework in which any spatially varying crosstalks and varying spatial-spectral correlations can be modeled and factored into the color reproduction. Simulation results show that the proposed technique is highly effective and capable to obtain both high color fidelity and sharp, clean spatial details.

For the new signal acquisition methodology of compressive sensing (CS) a challenge is to find a space in which the signal is sparse and hence recoverable faithfully. Given the nonstationarity of many natural signals such as images, the sparse space is varying in time or spatial domain. As such, CS recovery should be conducted in locally adaptive, signal-dependent spaces to counter the fact that the CS measurements are global and irrespective of signal structures. On the contrary existing CS reconstruction methods use a fixed set of bases (e.g., wavelets, DCT, and gradient spaces) for the entirety of a signal. To rectify this problem we propose a new model-based framework to facilitate the use of adaptive bases in CS recovery. In a case study we integrate a piecewise stationary autoregressive model into the recovery process for CS-coded images, and are able to increase the reconstruction quality by 2 ~ 7dB over existing methods. The new CS recovery framework can readily incorporate prior knowledge to boost reconstruction quality.

We propose a new image restoration algorithm that is driven by an adaptive piecewise autoregressive model (PAR). The strength of the new algorithm is its ability to preserve spatial structures better than its predecessors. The high adaptability is achieved by locally fitting 2D image waveform to the PAR model in moving windows. The problem is posed as one of nonlinear least-square estimation of both PAR parameters and original pixels, constrained by the degradation function. Robust solutions of the underlying underdetermined inverse problem are obtained by an innovative use of multiple PAR models that circumvent the issue of model overfitting, and by applying a structured total least-square technique.

We propose a new image acquisition and recovery strategy of hybrid sensing (HS) that combines random sampling of compressive sensing (CS) and uniform down sampling. HS lets the two sampling schemes complement each other so that one can have the best of both worlds: signal-independent sparse sampling that is the hallmark of CS, and locally adaptive signal reconstruction that is afforded by uniform sampling. We suggest a few important applications of HS in image acquisition and communication, such as multispectral imaging, multiple description image coding, multiview video, and ultra-high throughput imaging (e.g., functional medical imaging).

Recently, many researchers started to challenge a long-standing practice of digital photography: oversampling followed by compression and pursuing more intelligent sparse sampling techniques. In this paper, we propose a practical approach of uniform down sampling in image space and yet making the sampling adaptive by spatially varying, directional low-pass prefiltering. The resulting down-sampled prefiltered image remains a conventional square sample grid, and, thus, it can be compressed and transmitted without any change to current image coding standards and systems. The decoder first decompresses the low-resolution image and then upconverts it to the original resolution in a constrained least squares restoration process, using a 2-D piecewise autoregressive model and the knowledge of directional low-pass prefiltering. The proposed compression approach of collaborative adaptive down-sampling and upconversion (CADU) outperforms JPEG 2000 in PSNR measure at low to medium bit rates and achieves superior visual quality, as well. The superior low bit-rate performance of the CADU approach seems to suggest that oversampling not only wastes hardware resources and energy, and it could be counterproductive to image quality given a tight bit budget.

Recently, many researchers started to question a long-standing paradox in the engineering practice of digital photography: oversampling followed by compression, and pursue more intelligent sparse sampling techniques. In this research we take a practical approach of uniform down sampling in image space, and the sampling is made adaptive by a spatially varying directional low-pass prefiltering. Since the down-sampled prefiltered image is a low-resolution image of conventional square sample grid, it can be compressed and transmitted without any change to current image coding standards and systems. The decoder first decompresses the low-resolution image and then upsamples it to the original resolution by least-square estimation using a 2D piecewise autoregressive model and the knowledge of directional low-pass filter. The proposed joint adaptive down-sampling and up-sampling technique outperforms JPEG 2000 (the state-of-the-art in lossy image coding) in PSNR measure at low to modest bit rates and achieves superior visual quality at all bit rates. This work shows that oversampling not only increases cost and energy consumption, but it could, even when coupled with a sophisticated rate-distortion optimized compression scheme, cause inferior image quality at certain bit rates.

We propose a practical standard-compliant multiple description (MD) image coding technique. Multiple descriptions of an image are generated in the spatial domain by an adaptive prefiltering and uniform down sampling process. The resulting side descriptions are conventional square sample grids that are interleaved with one the other. As such each side description can be coded by any of the existing image compression standards. A side decoder reconstructs the input image by first decompressing the down-sampled image and then solving a least-squares inverse problem, guided by a two-dimensional windowed piecewise autoregressive model. The central decoder is algorithmically similar to the side decoder, but it improves the reconstruction quality by using received side descriptions as additional constraints when solving the underlying inverse problem. Compared with its predecessors the proposed image MD technique offers the lowest encoder complexity, complete standard compliance, competitive rate-distortion performance, and superior subjective quality.

The challenge of image interpolation is to preserve spatial details. We propose a soft-decision interpolation technique that estimates missing pixels in groups rather than one at a time. The new technique learns and adapts to varying scene structures using a 2-D piecewise autoregressive model. The model parameters are estimated in a moving window in the input low-resolution image. The pixel structure dictated by the learnt model is enforced by the soft-decision estimation process onto a block of pixels, including both observed and estimated. The result is equivalent to that of a high-order adaptive nonseparable 2-D interpolation filter. This new image interpolation approach preserves spatial coherence of interpolated images better than the existing methods, and it produces the best results so far over a wide range of scenes in both PSNR measure and subjective visual quality. Edges and textures are well preserved, and common interpolation artifacts (blurring, ringing, jaggies, zippering, etc.) are greatly reduced.

Considering that quincunx lattice is a more efficient spatial sampling scheme than square lattice, we investigate a new approach of image coding for quincunx sample arrangement. The key findings are: 1) adaptive directional lifting is particularly suited to decorrelate samples on quincunx lattice, and 2) quincunx samples can be processed by a 2D piecewise autoregressive model to reproduce the image of conventional square pixel grid, while preserving high frequency spatial features well. By incorporating these two techniques into the encoder and decoder respectively, we are able to improve the performance of JPEG 2000 image codec at low to modest bit rates. Since an image can be easily split into quincunx segments, this work has significance for multiple description image/video coding as well

The performance of image interpolation depends on an image model that can adapt to nonstationary statistics of natural images when estimating the missing pixels. However, the construction of such an adaptive model needs the knowledge of every pixels that are absent. We resolve this dilemma by a new piecewise 2D autoregressive technique that builds the model and estimates the missing pixels jointly. This task is formulated as a non-linear optimization problem. Although computationally demanding, the new non-linear approach produces superior results than current methods in both PSNR and subjective visual quality. Moreover, in quest for a practical solution, we break the non-linear optimization problem into two subproblems of linear least-squares estimation. This linear approach proves very effective in our experiments.

We propose a new image compression technique based on adaptive edge-guided interpolation. The design criterion of the new image compression technique is a perceptual one. We aim to preserve the spatial correlation structures of image edges because human visual system is highly sensitive to distortions of spatial coherence of edges. Experimental results show that the proposed technique indeed achieves superior visual quality than JPEG 2000 at low to modest bit rates. For situations when the encoder has limited computing resources and/or power supply (e.g., wireless communications and sensor networks), the new technique has the desirable property of low encoding complexity.

We propose a new non-linear approach of high order context to image interpolation. A global texture orientation map is generated by directional Gabor filters to estimate the edge directions in subpixel precision. The interpolation direction is further refined by a kernel Fisher discriminant that exploits prior knowledge gained from a training set. Experiments show that the proposed method can preserve edge sharpness and subdue the ringing artifacts better than the existing methods, and it obtains higher PSNR as well.