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[TOC] 一阶低通滤波 一阶低通滤波，又叫 一阶惯性滤波，其算法公式为： \[Y_k = \alpha X_k + (1-\alpha) Y_{k-1}\] 根据安卓开发者文档中提供的低通滤波算法： // https://developer.android.com/guide/topics/sensors/sensors_motion#java public void onSensorChanged(SensorEvent event){ // In this example, alpha is calculated as t / (t + dT), // where t is the low-pass filter's time-constant and ...

[TOC] Ego-motion Ego-motion is defined as the 3D motion of a system (ex camera) within an environment. Visual Odometry Odometry is generally used to refer to an elapsed or relative position and orientation and, because it is not absolute, is prone to drift over time. Visual odometry in general is the estimation of ego-m...

[TOC] Overview Bundle adjustment (wikipedia) BA is a key ingredient of Structure and Motion Estimation (SaM), almost always used as its last step It is an optimization problem over the 3D structure and viewing parameters (camera pose, intrinsic calibration, radial distortion parameters), which are simultaneous...

[TOC] Overview EKF and ESKF: EKF: Extended Kalman Filter –> Direct Kalman Filter ESKF: Error State Kalman Filter –> Indirect Kalman Filter Estimator State Types: True State Nominal State Error State ESKF Advantages: The orientation error-state is minimal (i.e., it has the same number of parameters as degrees of...

[TOC] MSCKF typedef std::map<FeatureIDType, Feature, std::less<int>, Eigen::aligned_allocator<std::pair<const FeatureIDType, Feature> > > MapServer; struct Feature { FeatureIDType id; Eigen::Vector3d position; std::map<StateIDType, Eigen::Vector4d, std::less<StateIDType>, Eigen::aligned_allocator...

[TOC] Overview 忽略掉了 shift to base frame：w_t_vio, w_r_vio loop closure 初始化 PoseGraph 设置 设置参数 启动线程 PoseGraph::optimize4DoF 或 PoseGraph::optimize6DoF 加载 词典文件 启动线程 SystemROS::loop_closing 线程 loop_closing 获取同步的图像、位姿、2D与3D点信息 img pose point_id, point_3d, point_2d_uv, ...

ref: https://vision.in.tum.de/data/datasets/visual-inertial-dataset

[TOC] Overview Oriented FAST + Rotated BRIEF Feature/Corner Detector FAST方法 – 定位特征点坐标 矩方法 – 特征点方向 非极大值抑制 – 特征点响应值（分数） 图像金字塔 – 特征点具有 尺度不变性 Descriptor BRIEF – 特征点描述子 特征点方向 – 描述子具有 旋转不变性 oFAST: FAST Keypoint Orientation Multiscale Image Pyramid level: 8 scale: 1.2 down sample: bilinear ...