Kaichun Zhao

Shape from polarization based on a polarization representation and sparse self-attention

Zhenhua Wan, J. W. Wu, K. H. Li, Zhichao Yu et autres

Accurate estimation of surface normals plays a crucial role in 3D reconstruction tasks. Physics-based shape from polarization (SfP) methods face numerous limitations, such as difficulty in handling mixed reflections and local ambiguities. In contrast, deep learning-based SfP methods surpass physics-based approaches in …

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Full-System Simulation and Analysis of a Four-Mass Vibratory MEMS Gyroscope

Chenguang Ouyang, Wenzheng He, Lu Jia, Peng Wang et autres

This study presents a full-system simulation methodology for MEMS, addressing the critical need for reliable performance prediction in microsystem design. While existing digital tools have been widely adopted in related fields, current approaches often remain fragmented and focused on specific aspects of …

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Stereo Event-Based Visual–Inertial Odometry

Kunfeng Wang, Kaichun Zhao, Wenshuai Lu, Zheng You

Event-based cameras are a new type of vision sensor in which pixels operate independently and respond asynchronously to changes in brightness with microsecond resolution, instead of providing standard intensity frames. Compared with traditional cameras, event-based cameras have low latency, no motion blur, …

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面向无人机目标探测的分时型红外偏振成像系统

GUO Jie, Kaichun Zhao

针对分时型红外偏振成像系统在快速成像过程中的偏振响应稳定性问题，设计了一种长波红外偏振成像系统，用于无人机目标在红外强杂波背景下的目标探测。对偏振步进角度进行最优分析，通过角度误差模型仿真确定系统的最优步进角参数，从而减少偏振误差；设计了自适应检偏角度估计算法，通过时变参数型卡尔曼滤波算法实现角度的准确估计，以满足该系统在高转速下输出稳定偏振响应的需求。实验结果表明：在50 Hz的工作成像帧率下，经过滤波算法处理后的系统偏振响应波动降低91%，系统的偏振度精度达到了0.50%，偏振角精度达到了1.52°，相较于红外图像，偏振图像中的目标区域对比度可提升3~10倍。该成像系统能够提升无人机目标的对比度，满足红外强杂波背景下无人机目标的探测需求。

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Visual-Inertial Localization Leveraging Skylight Polarization Pattern Constraints

Zhenhua Wan, Kunfeng Wang, Kaichun Zhao

In this letter, we develop a tightly coupled polarization-visual-inertial localization system that utilizes naturally-attributed polarized skylight to provide a global heading. We introduce a focal plane polarization camera with negligible instantaneous field-of-view error to collect polarized skylight. Then, we design a robust …

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Measurement Modeling and Performance Analysis of a Bionic Polarimetric Imaging Navigation Sensor Using Rayleigh Scattering to Generate Scattered Sunlight

Zhenhua Wan, Kaichun Zhao, Haoyuan Cheng, Peng Fu

The bionic polarimetric imaging navigation sensor (BPINS) is a navigation sensor that provides absolute heading, and it is of practical engineering significance to model the measurement error of BPINS. The existing BPINSs are still modeled using photodiode-based measurements rather than imaging measurements …

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Adaptive visual inertial geomagnetic tightly coupled positioning system

Peng Fu, Zhen‐Hua Wan, Kunfeng WANG, Kaichun Zhao

为了解决视觉惯性组合导航系统绝对航向信息缺失与姿态发散的问题，进一步提升系统定位精度，设计并实现了针对未知磁场环境下的自适应视觉惯性地磁紧耦合定位系统。基于常用的三轴磁力计内外参数联合标定原理，提出了一种地磁信息全局及帧间约束残差构建方法。通过磁强度差异动态调整融合权重，利用非线性优化方法设计视觉/惯性/地磁紧耦合系统实现自身运动状态估计。最后，在校园环境下开展户外实验。实验结果表明：该系统能够在部分建筑及车辆磁场干扰环境下稳定运行，定位精度均优于0.8%（RMSE），相比于VINS位置误差平均降低了约24%，且具有良好的实时性。磁力计及自适应融合方法的引入可以有效改善现有视觉惯性导航系统的定位性能，为无人系统提供高可靠性的实时定位结果。

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Shape from polarization based on sparse self-attention

Zhiyang Yu, Zhen‐Hua Wan, Kaichun Zhao

对于物体表面法线的准确估计在各种计算机视觉任务中扮演着重要角色。采用基于物理的偏振表面法线估计方法存在诸多限制，限制了其实用性。相反，基于深度学习的偏振表面法线估计方法在精度和适用性上均超越了基于物理的方法，为了进一步提高基于深度学习的偏振表面法线估计精度，以使其能适用于更多的实际任务，本文提出了一种新的方法。首先，结合斯托克斯矢量提出了一种新的偏振信息表示方法，旨在提高模型对偏振物理先验信息的提取能力。随后结合基于双层路由的稀疏自注意力机制，以改进模型对全局上下文信息的感知能力，来更好地对局部偏振信息消歧。在DeepSfP数据集和自建测试数据进行测试。实验结果表明：提出的方法在DeepSfP数据集上平均角度误差为13.37°，并在精度和角度误差等所有测试指标上均优于现有方法，证明了该方法在估计法线效果方面的显著改进。通过引入新的偏振信息表示方法和稀疏自注意力机制，我们的方法提高了偏振表面法线估计的精度和适用性，为实际任务的应用提供了更强的支持。

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Measurement Modeling and Performance Analysis of a Bionic Polarization Imaging Navigation Sensor Using Rayleigh Scattering to Generate Scattered Sunlight

Zhenhua Wan, Kaichun Zhao, Haoyuan Cheng, Peng Fu

The bionic polarization imaging navigation sensor (BPINS) is a navigation sensor that provides absolute heading, and it is of practical engineering significance to model the measurement error of BPINS. The existing BPINSs are still modeled using photodiode-based measurements rather than imaging measurements …

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A semantic vector map-based approach for aircraft positioning in GNSS/GPS denied large-scale environment

Chenguang Ouyang, Suxing Hu, Fengqi Long, Shuai Shi et autres

Accurate positioning is one of the essential requirements for numerous applications of remote sensing data, especially in the event of a noisy or unreliable satellite signal. Toward this end, we present a novel framework for aircraft geo-localization in a large range that …

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Stereo Event-based Visual-Inertial Odometry

Kunfeng Wang, Kaichun Zhao

Event-based cameras are new type vision sensors whose pixels work independently and respond asynchronously to brightness change with microsecond resolution, instead of providing standard intensity frames. Compared with traditional cameras, event-based cameras have low latency, no motion blur, and high dynamic range …

Calibration of signal-to-noise ratio of sub focal plane polarization image sensors

Shuwang ZHU, Kaichun Zhao

为了标定分焦平面偏振图像传感器的信噪比，设计了分焦平面偏振图像传感器各通道信噪比标定实验。对分焦平面偏振图像传感器信噪比参数对偏振角度测量结果的影响程度、信噪比标定原理、标定实验流程等进行了研究。根据分焦平面偏振传感器的结构和数字图像传感器的数学模型得到信噪比的标定原理。在不同信噪比、不同入射角度线偏振光情况下，对偏振角度测量结果进行了仿真。然后，根据标定原理设计标定实验的装置结构和实验流程。最后，进行实际标定并对实验数据进行了分析。信噪比-偏振角度测量精度仿真结果表明：分焦平面偏振图像传感器的信噪比越大，偏振角度测量精度越高，且入射偏振光角度也会影响测量精度。分焦平面偏振图像传感器各通道信噪比参数的实际测试结果表明：标定值与指标值相差不超过0.55 dB。实验结果证明，该方法是准确有效的，能够较好地完成分焦平面偏振图像传感器各通道信噪比的标定任务。

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