Calculate Absolute Trajectory Error with ROS

Absolute Trajectory Error (ATE) 是衡量 SLAM 算法的一个重要指标。它描述了 SLAM 估计出来的机器人路径和 ground truth 之间的差异大小。显然 SLAM 算法的表现越好,那么估计出来的路径误差就会越小。

Ubuntu Won't Boot With Nvidia Driver Installed

I recently got a new Alienware M15 R6 gaming laptop computer from my lab. After installing Ubuntu (dual boot with Windows), the next thing to do is to utilize its RTX 3080 GPU by installing Nvidia drivers. The problem was with Nvidia drivers installed, the whole system won’t boot up. It just shows a black screen with some system prompt text and stuck.

How to fix

First Time Using a Total Station

全站仪(Total Station)是一种可以用来测量物体到机器角度、距离等数据的仪器。学土木工程或测绘的同学们对它都非常熟悉,但是作为一个 ECE 专业的学生,平时的确没什么机会接触到全站仪,感觉很好玩因此简单记录一下。


Readers / Writers Lock

在工程实践中,客户端需要从服务端拉取一个配置列表来决定自身的功能表现。几乎所有的 feature 都需要通过 settings 来判断自身的状态,例如是否应该开启本功能(如 A/B Testing),该显示什么样的文案,或是需要打开的 H5 链接是什么。可见,读取 settings 是一个非常高频的操作。在以前的工作中,通过运行 profiling 工具,也确实发现读取 settings 是耗时最久的高频函数。

Using python-pcl with Python3.6

PointCloud Library (PCL) 是一个用来处理点云数据的 C++ 库。python-pcl 是一个 Python 的桥接,让我们可以用 Python 调用 PCL 的大多数 API。然而 python-pcl 有些疏于维护,因此并没有办法简单得通过 pip install 的方式安装,会报错。


How to Build and Run VINS-Mobile

VINS-Mono is a SLAM framework developed by researchers at HKUST. The authors also published its mobile version, VINS-Mobile, which can run on iOS devices. Although they provided a pretty good README file to guide us on how to compile and run it, beginners may still feel confused. In this article, I’m going to document all the problems I met, and hopefully, it can be helpful for others.

The missing opencv2.framework

Bundle Adjustment using Ceres-Solver

Bundle Adjustment (BA) has a broad application in Structure From Motion (SFM) problems, which further optimize the location of points to achieve 3D reconstruction. In recent years, traditional filter-based SLAM algorithms have been taken place by optimization-based SLAM, in which BA is the core part. BA can simultaneously optimize camera poses as well as the locations of 3D points by minimizing the reprojection error.

VSCode sigset_t is Undefined

在使用 VSCode 写 signal 相关的代码时,IntelliSense 提示 sigset_t is undefined。

ORB Feature Extraction with OpenCV

Oriented FAST and rotated BRIEF (ORB) 特征是 SLAM 中比较常用的一种图像特征。它的准确率并没有 SIFT 高,但是其计算速度更快,可以满足实时特征提取的需求。ORB 特征还具有旋转、尺度不变性的特点,因此很适合应用在 SLAM 场景中。

Time-Frequency Uncertainty

The Uncertainty Principle is first proposed by Heisenberg to describe that you can’t precisely measure the position and momentum of a particle at the same time. This principle is well known in quantum physics. It then became a very “general” idea, and can also be used in the field of signal processing. In this article, I will describe the time-frequency uncertainty principle theorem and then show the proof.

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