Choi's blog

This article is for personal use to review the way to create a dynamic AABB tree in Python. Broad Phase Collision Detection Before resolving collisions between objects in a simulation, we have to know which object pairs collide. However, when you test collisions between $n$ rigid objects in a physics simulation, there will be a total of $\frac{n(n+1)}{2}$ collision checks, causing the algorithm ..

This article is for personal use to record the way to do servo control "Parallax Feedback 360° High Speed Servo" in ESP32 microcontrollers. What is Continuous Servo Motor? Servo motors are closed-loop systems that usually use feedback loops to control position. Because of its high torque compared to its size and ease of use, it is often used for robotics applications. I also frequently use servo..

Long-range Video When I want to integrate a camera with some robot projects, I usually use ESP32-CAM modules, which are cheap and pretty fast. However, that only works when we have wi-fi available or are close to the module during AP mode. Sometimes, we want to receive video from very remote places, and my solution for it was to use FPV modules that many drone hobbyists use. FPV modules use radi..

This article is for personal use to review the way to web crawl images from different websites. Why Image Crawler? When I was studying object classifiers or detectors using deep learning methods, getting the right images to train was always the laborious part. Even though there are many existing image datasets that can be used, those sometimes did not have the object categories that I wanted or ..

This article is for personal use to review the way to create signed distance functions from 3D mesh using JAX. Triangle Mesh (Tri-mesh) Mesh is the common data representation of 3D objects. However, there are different kinds of mesh. Triangle mesh and quadrilateral mesh are the most common types that only save surface information. Quadilateral mesh is more accurate and mainly used for flow simul..

This article is for personal use to review self-organizing map, which is an unsupervised learning technique. What is Self-organizing Map (SOM)? According to Wikipedia, we get the following definition about self-organizing map. A self-organizing map (SOM) or self-organizing feature map (SOFM) is an unsupervised machine learning technique used to produce a low-dimensional (typically two-dimensiona..

This article is for personal use to review and organize the existing way to visualize signed distance functions for 3D mesh using JAX. What is Signed Distance Function (SDF)? According to Wikipedia, we get the following definition about signed distance function. In mathematics and its applications, the signed distance function (or oriented distance function) is the orthogonal distance of a given..

This article is for personal use to roughly review basic oriented bounding volume algorithms and practice JAX coding. Caution Before starting to read this article, I recommend you read the previous article about "Oriented Minimum Bounding Box" since it talks about the basic concepts of bounding volume and its need. What is Bounding Volume? According to the Wikipedia, we get a following definitio..

This article is for personal use to archive the visulization method for physics simulation in Google Colab. Caution Before we begin, I strongly recommend you just use your personal computer environment to visualize the physics engine. There is no "practical" way to render the physics engine in Colab, and modern computers are very good at rendering thanks to the game community. The reason I am wr..

This article is for personal use to roughly review basic oriented bounding box algorithms and practice JAX coding. What is Oriented Minimum Bounding Box? According to the Wikipedia, we get the following definitions about different bounding boxes. 1. Minimum bouding box In geometry, the minimum or smallest bounding or enclosing box for a point set S in N dimensions is the box with the smallest me..