在 ARKit 中获取设备围绕世界原点 y 轴的旋转 [英] Getting the rotation of device around the world origin's y axis in ARKit

问题描述

当我在 ARKit 中围绕 y 轴旋转我的设备时，我试图计算它的旋转.为了澄清起见，ARKit 中的 y 轴是垂直于地面指向上方的轴.

I am trying to calculate the rotation of my device when I rotate it around the y-axis in ARKit. For clarification the y-axis in ARKit is the axis pointing upwards perpendicular to the ground.

我像这样使用欧拉角来获得相机的旋转:

I used eulerangles to get the rotation of the camera like this:

var alpha = sceneView.pointOfView?.eulerAngles.y

当 0=<alpha<pi/2 和 -pi/2<alpha<=0 时，这大致有效，但是对于应该是其他角度的情况，我得到了错误的读数.我怀疑这与万向节锁定有关，并且我必须以某种方式使用四元数才能获得正确的角度，而不管象限如何.非常感谢任何帮助！

This approximately works when 0=<alpha<pi/2 and when -pi/2<alpha<=0, but for what is supposed to be other angles I get the wrong readings. I suspect this has to do with gimbal lock and that I have to somehow use quaternions to be able to get the correct angle regardless of quadrant. Any help is much appreciated!

推荐答案

通过使用四元数而不是欧拉角来解决它.这是我使用的代码:

Solved it by using quaternions instead of eulerangles. This is the code I used:

  guard let cameraNode = sceneView.pointOfView else { return }

  //Get camera orientation expressed as a quaternion
  let q = cameraNode.orientation

  //Calculate rotation around y-axis (heading) from quaternion and convert angle so that
  //0 is along -z-axis (forward in SceneKit) and positive angle is clockwise rotation.
  let alpha = Float.pi - atan2f( (2*q.y*q.w)-(2*q.x*q.z), 1-(2*pow(q.y,2))-(2*pow(q.z,2)) )

我使用了 this 中列出的四元数到标题/euler 转换网站.

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