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CG from Zero [A] to Hero [Z]_



OBSERVABILITY AND INCONSISTENCY IN A NUTSHELL

[TOC] Overview What is observability ? In control theory, observability is a
measure for how well internal states of a system can be inferred by knowledge of
its external outputs. What is consistenc
2022-07-16
State Estimation
#State Estimation #Observability and Consistency #FEJ #Lie Theory #Observability
Matrix #OC-VINS #Degeneracy


基于RGBD相机的多模态结构特征融合定位 (DRAFT)

[TOC] 概述
目前基于RGBD相机的视觉SLAM系统，都是基于特征点或者稠密点云进行定位，计算量大，而且在无纹理或弱纹理的环境，容易跟丢，鲁棒性较差。本文提出了一种基于RGBD相机的多模态结构化数据融合定位方法，算法主要框架如下图所示，通过充分利用视觉特征，融合二维特征点、二维曲线（边缘点）、二维线段和三维平面等，结合状态估计算法进行实时、鲁邦、准确的位姿估计。在二维特征点的基础上，同时提取边
2022-03-06
MSF
#Image Features #Visual SLAM #Multi-Sensor Fusion #Parameterization #Struct SLAM


FROM MAP, MLE, OLS, G-N TO IEKF, EKF

[TOC] Overview 本文主要包括以下几个方面：
将线性高斯系统的状态空间方程(运动和观测方程，即多个似然因子)组合为一个新的观测方程，其实就是将多个约束项放在一起 推导了MAP到MLE，再到OLS的历程
以上面系统的状态估计为出发点，推导了最小二乘、高斯牛顿、IEKF和EKF的区别与联系，将优化与滤波联系在一起，导出了高斯牛顿海塞矩阵H与EKF协方差矩阵P的关系，证明了IEKF与高斯牛
2021-12-30
State Estimation
#EKF #State Estimation #MAP


MARGINALIZATION AND FEJ IN SLIDING WINDOW VIO

[TOC] Overview 滑动窗口与共视图 我们根据 时空 对 局部BA 进行分类： 时间：滑动窗口 空间：共视图 通过
企业管理，解释滑窗的边缘化以及共视图为啥没有边缘化：
基于滑窗优化的边缘化，可以用公司小组成员离职类比，小组相当于滑窗，离职交接相当于保留共视信息，没有交接就回影响小组未来的发展；交接不好，重新搞；员工贡献不大直街裁掉，就是remove或throw；而基于共视图的，相
2021-07-04
SLAM
#Visual SLAM #VIO #Sliding Window #Observability and Consistency
#Marginalization #FEJ


BUNDLE ADJUSTMENT (BA) IN VSLAM OR SFM

[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 structur
2021-02-04
State Estimation
#Graph #Visual SLAM #SFM #Optimization #State Estimation #Bundle Adjustment #OLS


LINEAR ALGEBRA IN A NUTSHELL

Matrix 厄米特矩阵 埃尔米特矩阵等于自己的 共轭转置 厄米特矩阵 \(A^H = A\) 实对称矩阵 \(A^T = A\) 反厄米特矩阵 \(A^H =
-A\) 实反对称矩阵 \(A^T = -A\) 正规矩阵 \[ A^H A = A A^H \] 酉矩阵 \(A^H A = A A^H = I\) 正交矩阵
\(A^T A = AA^T = I\) 特殊正交矩阵：\
2019-01-28
Maths
#Matrix Decomposition


双目立体视觉原理

[TOC] Overview 双目立体视觉的整体流程包括： 图像采集 双目标定 双目矫正 立体匹配 三维重建 1. 图像采集 双目相机采集 左右目图像 2.
双目标定 通过 双目标定工具 对双目相机进行标定，得到如下结果参数： 内参 外参 相机矩阵 \(K_1, K_2\) 旋转矩阵 \(R\) 畸变系数
\(D_1, D_2\) 平移向量 \(t\) 《Lear
2018-07-22
Computer Vision
#Computer Vision #Stereo Vision


WHEN SLAM MEETS XR AND ROBOTICS

When SLAM meets XR When SLAM meets Robotics
2022-12-24
SLAM


GPG OVERVIEW

Overview PGP目前支持的算法 非对称算法: RSA, ELG, DSA, ECDH, ECDSA, EDDSA 对称算法: IDEA, 3DES,
CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH, CAMELLIA128, CAMELLIA192,
CAMELLIA256 哈希算法: SHA1, RIPEMD160, SHA256, SHA3
2022-12-12
DevOps
#GPG


移动机器人常见底盘及其运动学

Overview [1]
通常移动机器人依赖电机驱动车轮实现行走功能。机器人底盘结构不同，其运动学也完全不同。根据不同类型车轮，常见的底盘结构差速运动模型、滑移运动模型、阿克曼运动模型、全向轮运动模型等等。
下图中，（a）双轮差速式机器人，（b）阿克曼式机器人，（c）四轮驱动机器人，（d）双履带式机器人，（e）麦克纳姆轮全向机器人，（f）全向轮全向机器人，（g）四轮驱动四轮转向机器人
[2]
2022-11-22
Robotics
#Kinematics #RobotBase


ON-MANIFOLD OPTIMIZATION: LOCAL PARAMETERIZATION

Overview Manifold Space vs Tangent Space Jacobian w.r.t Error State Jacobian
w.r.t Error State vs True State According [1] 2.4, The idea is that for a \(x
\in N\) the function \(g(\delta) := f (x
2022-09-04
State Estimation
#Optimization #Parameterization #Kinematics #State Estimation #Lie Theory
#Manifold #Quarternion


MAPILLARY API AT A GLANCE

Embed images [1] The iframe tag below would show a 640x480px image with ID
550092599700936. 123456<iframe
src="https://www.mapillary.com/embed?image_key=550092599700936&style=classic"
heigh
2022-07-24
GIS
#GIS #Mapillary


PYTORCH ON UBUNTU 18.04

[TOC] Install PyTorch locally https://pytorch.org/get-started/locally/ Conda
(Python) 12345678910conda create -n torch python=3.9conda activate torch# select
oneconda install pytorch -c soumith c
2022-06-25
ML
#Machine Learning #Deep Learning #PyTorch


YOLO TEST ON UBUNTU 18.04

[TOC] YOLO Darknet: Open Source Neural Networks in C YOLO: Real-Time Object
Detection Build / Install Detection Using A Pre-Trained Model 1./darknet detect
cfg/yolov3.cfg yolov3.weights data/dog.jpg
2022-06-25
ML
#Machine Learning #Deep Learning #Object Detection #Yolo


IMAGE EXPOSURE CONTROLLER

msckf-vio Issue: About image exposure controller #41 [1] The auto exposure code
is not open source because for one the actual implementation is ugly, and second
because it ties into other software
2022-06-22
Computer Vision
#Computer Vision #Camera #Camera Control #Driver


A-LOAM

[TOC] Overview A-LOAM is an Advanced implementation of LOAM (J. Zhang and S.
Singh. LOAM: Lidar Odometry and Mapping in Real-time), which uses Eigen and
Ceres Solver to simplify code structure. Cod
2022-06-19
SLAM
#LiDAR SLAM #LIO


OPENMVG + OPENMVS BUILD & RUN

[TOC] Overview OpenMVG provides an end-to-end 3D reconstruction from images
framework compounded of libraries, binaries, and pipelines. a library mainly
focused on Multiple-View-Geometry and Structu
2022-06-18
Mapping
#3D Reconstruction #Mapping #SFM


MESH TEXTURING IN A NUTSHELL (LET THERE BE COLOR)

[TOC] .graphviz { display: flex; justify-content: center; } Overview digraph {
TV [label="TextureView"]; TVs [label="N TextureViews"]; Texturing [style=filled,
shape=box]; ColorImg->TV;
2022-06-12
Mapping
#Graph #3D Reconstruction #Mapping #Texturing #MAP-MRF #Dynamic Programming
#Belief Propagation


KINECT FUSION

[TOC] Overview Kinect Fusion 描述三维空间的方式叫
Volumetric。它把固定大小的一个空间（比如3𝑚×3𝑚×3𝑚）均匀分割成一个个小方块（比如512×512×512），每个小方块就是一个voxel，存储TSDF值以及权重。最终得到的三维重建就是对这些voxel进行线性插值。
重建流程如上图所示： Depth Map Conversion: 读入的深度
2022-06-10
Mapping
#3D Reconstruction #Visual SLAM #Mapping #TSDF


CMAKE FOR VISUAL STUDIO

[TOC] Property Sheet example main.props, 在此文件 设置工程，方便分享
12345678910111213141516171819202122232425262728293031323334<?xml version="1.0"
encoding="utf-8"?><Project DefaultTargets="Build" xml
2022-06-01
DevOps
#Cpp #Visual Studio #CMake
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