Navigating the complexities of coordinate frames: A guide to understanding the differences in Three.js, ROS, and Unreal Engine
Coordinate frames are an important aspect of robotics and computer graphics, as they determine the position and orientation of objects in 3D space. However, different platforms and software libraries use different conventions for their coordinate frames, which can lead to confusion and errors when working with multiple systems.
Three.js, ROS, and Unreal Engine are all popular platforms in their respective fields, but each has its own unique coordinate frame. Three.js uses a right-handed coordinate frame, where the positive x-axis points to the right, the positive y-axis points up, and the positive z-axis points towards the viewer. On the other hand, ROS uses a left-handed coordinate frame, where the positive x-axis points to the right, the positive y-axis points down, and the positive z-axis points away from the viewer. Unreal Engine also uses a left-handed coordinate frame, but the positive y-axis points up and the positive z-axis points towards the viewer.
To convert from one coordinate frame to another, it is important to take into account the left-hand or right-hand rule. The left-hand rule states that if you curl the fingers of your left hand in the direction of the positive x-axis, y-axis, and z-axis, your thumb will point in the direction of the positive z-axis. The right-hand rule is the opposite, where if you curl the fingers of your right hand in the direction of the positive x-axis, y-axis, and z-axis, your thumb will point in the direction of the positive z-axis.
When calibrating sensors, it is important to perform coordinate frame transformations to ensure that the data is being recorded and interpreted correctly. This involves taking into account the order of operations for the angles and the polarity of the angles, as well as any other variations in the coordinate frame conventions. To facilitate this process, it is useful to use a markup language, such as the Extensible Markup Language (XML) or the Robot Operating System (ROS) Parameter Server, to describe the transformations and parameters.
In summary, Three.js, ROS, and Unreal Engine all use different coordinate frames, and converting between them requires taking into account the left-hand or right-hand rule. Sensor calibration also requires the use of coordinate frame transformations, and using a markup language to describe these transformations can make the process more manageable