Camera Calibration with OpenCV and Kinect

I have been recently working on projects that use the Microsoft Kinect, and also had the chance to use OpenCV to calibrate the color camera in the Kinect. This is because one of the projects use Aruco AR markers and to obtain the orientation of the Aruco markers, we need the camera's internal parameters and therefore, calibration! The Kinect's camera is just like any other webcam, so there is nothing special about it. But I thought the calibration process can help others who are just starting to use OpenCV and need to get camera internal parameters.

The code can be found here.
You need to prepare a calibration board with checker patterns with known length. The pattern image is also included in the repository but you'll need to find a sturdy planar object such as a wooden board.

Currently there is not any UI so it's probably good to share here that after you position your checker board you need to manually press 'c' to capture an image. Repeat this 10 times and a file named "camera_parameters.yml" will be generated in the same folder as the exe file.

Credit : The Kinect capture code is based on samples from this repository.

Comments

Using FCM with the new HTTP v1 API and NodeJS

When trying to send FCM notifications I found out that Google has changed their API specifications. The legacy API still works but if you want to use the latest v1 API you need to make several changes. The list of changes is listed on their site so I won't be repeating them again but I'll just mention some of the things that caused some trial and error on my project. The official guide from Google is here : Official Migration Guide to v1 . The request must have a Body with the JSON containing the message data. Most importantly it needs to have "message" field which must contain the target of the notification. Usually this is a Topic, or Device IDs. Since my previous project was using GAS, my request had a field called "payload" instead of "body". Using the request from my previous project, my request in Node JS was as follows: request ({ url: 'https://fcm.googleapis.com/v1/projects/safe-door-278108/messages:send' , method: ...

Building a native plugin for Intel Realsense D415 for Unity

Based on a previous post , I decided to write a plugin for the Intel Realsense SDK methods so we can use these methods from within Unity. FYI Intel also has their own Unity wrapper in their Github repository , but for our projects, I needed to perform image processing with OpenCV and passing the results to Unity instead of just the raw image/depth data. There is a plugin called OpenCVForUnity to use OpenCV functions from Unity but previous experiments indicate the image processing inside Unity can take a long time. I hope this post can help someone else who wants to use Intel's cameras or any other devices natively in Unity. Test Environment Windows 10 64bit Unity 2017.2.0f3 x64 bit Realsense SDK from Intel CMake 3.0 or higher Steps Checkout the native plugin code here . Don't worry about the other projects in the same repository. The relevant code is in the link above. Checkout the Unity sample project here . However, instead of master you need to go to the br...

Microsoft Azure Face API and Unity

During one of my projects, I came across Microsoft's face recognition API (Azure Face API) and it looked good enough to recognize people's faces and detect if a person is a newcomer or a repeating customer to our store. As our installations mainly use the game engine Unity, I wanted to be able to use the Face API from Unity. Face API does not have an SDK for Unity but their requests are just HTTP requests so the Networking classes in Unity can be wrapped into methods to make it easy to call these APIs. First of all, to those who just want to see the code, here it is . My tests focus on the identification of a face in an input image. The full tutorial I followed can be found here . The Main scene goes through the steps in the tutorial such as creating a PersonGroup and adding Persons to the group if it is not created yet. Just make sure you: Change the API key. I used a free trial key which is no longer valid. Use whatever images you want. I don't mind you us...

Time is a limited resource

Search This Blog