如何将 3D 关节点（变换）投影到 2D 屏幕 ARKit 上？

Question

我正在尝试使用 ARKit 将 3D 人体关节点投影到 iPhone 的屏幕上。

1. 我正在提取全局变换：

    let rightArmPosition = skeleton.modelTransform(for: ARSkeleton.JointName(rawValue: "right_arm_joint"))!
    let rootPosition = skeleton.modelTransform(for: .root)!

2. 我正在计算偏移量

    let rightOffset = simd_make_float3(rightArmPosition.columns.3)
    let rootOffset = simd_make_float3(rootPosition.columns.3)

3. 我正在预测积分

let pMatrix = camera.projectionMatrix
        
let pRightOffset = camera.projectPoint(rightOffset, orientation: .portrait, viewportSize: CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height))
        
let pRootOffset = camera.projectPoint(rootOffset, orientation: .portrait, viewportSize: CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height))
        
humanJointsView.frame = UIScreen.main.bounds
humanJointsView.points = [pRightOffset, pRootOffset]

4. 我正在尝试在目标视图中绘制点：

override func draw(_ rect: CGRect) {
        path.removeAllPoints()
        self.points.forEach { point in
            path = UIBezierPath(ovalIn: CGRect(x: point.x, y: point.y, width: CGFloat(30), height: CGFloat(30)))
            UIColor.green.setFill()
            path.fill()
        }
    }

但是这种方法不起作用，我的错误在哪里？

谢谢！

Answer 1

右臂和根变换在骨架模型空间中，您需要将它们与身体锚点变换相乘。

rightArmWorldTransform = body.transform * rightArmPosition