使用ARKit进行面部追踪（使用Vision）

Question

我目前正在使用Vision和ARKit来查找框架中的任何面孔。我用来执行此操作的代码如下：

func runFaceDetection() {
        let pixelBuffer : CVPixelBuffer? = (sceneView.session.currentFrame?.capturedImage)
        if pixelBuffer == nil { return }
        let ciImage = CIImage(cvPixelBuffer: pixelBuffer!)
        let imageRequestHandler = VNImageRequestHandler(ciImage: ciImage, options: [:])

        do {
            try imageRequestHandler.perform(self.visionRequests)
        } catch {
            print(error)
        }
}

我正在使用以下代码尝试将这些返回的矩形映射到给定的面：

func faceRectanglesCompletionHandler(request: VNRequest, error: Error?) {
        if error != nil {
            print("error: " + (error?.localizedDescription)!)
            return
        }

        guard let faces = request.results else {
            print("No faces found in frame")
            return
        }

        DispatchQueue.main.async {
            for faceRect in self.faceRects {
                faceRect.removeFromSuperview()
            }

            self.faceRects = []

        }

        for face in faces {
            let observation = face as! VNFaceObservation
            print(observation.boundingBox)

            let newWidth = bounds.width * observation.boundingBox.width
            let newHeight = bounds.height * observation.boundingBox.height
            let newX = bounds.width * observation.boundingBox.origin.x
            let newY = bounds.height * observation.boundingBox.origin.y
            let newBoundingBox = CGRect(x: newX, y: newY, width: newWidth, height: newHeight)

            DispatchQueue.main.async {
                let faceView = UIView.init(frame: newBoundingBox)
                faceView.backgroundColor = .red
                faceView.alpha = 0.5
                self.faceRects.append(faceView)
            }
        }

        DispatchQueue.main.async {
            for faceRect in self.faceRects {
                self.view.addSubview(faceRect)
            }
        }
    }

问题是这不能正确地将脸部矩形映射到屏幕上的点。我的viewController的bounds属性设置为bounds = sceneView.bounds，其中sceneView是我的AR场景。当面部矩形出现时，它们通常不会出现，它们将显示为具有太多高度和宽度不足的细长矩形。我在映射代码中做错了什么？问题的图像如下。