swift - 没有得到正确的裁剪图像？

Question

我正在使用 ARKit 扫描面部并通过func scanForFaces()以 1 秒的间隔调用来获取 ARSession 的当前帧，然后通过裁剪图像仅裁剪该图像到面部，但我得到的是从图像顶部而不是从面部裁剪的图像与图像

   private func scanForFaces() {

        //remove the test views and empty the array that was keeping a reference to them
        _ = scannedFaceViews.map { $0.removeFromSuperview() }
        scannedFaceViews.removeAll()

        //get the captured image of the ARSession's current frame
        guard let capturedImage = sceneView.session.currentFrame?.capturedImage else { return }

        let image = CIImage.init(cvPixelBuffer: capturedImage)
        let cimage = self.convertCIImageToCGImage(inputImage: image)

        let detectFaceRequest = VNDetectFaceRectanglesRequest { (request, error) in

            DispatchQueue.main.async {
                //Loop through the resulting faces and add a red UIView on top of them.
                if let faces = request.results as? [VNFaceObservation] {
                    for face in faces {

                        let faceView = UIView(frame: self.faceFrame(from: face.boundingBox))
                        faceView.backgroundColor = .red
                        self.sceneView.addSubview(faceView)
                        let rotatedimage1 = UIImage(cgImage: cimage!).rotate(radians: .pi/2).fixImageOrientation()
                        var frame = self.faceFrame(from: faceView.bounds)
                        frame.origin = faceView.frame.origin
                        let imagefix =  self.crop(imageToCrop: rotatedimage1!, toRect: frame)
                        print(frame)
                        let abcview = self.storyboard?.instantiateViewController(withIdentifier: "MyViewController") as! MyViewController
                        abcview.image = imagefix
                        self.navigationController?.pushViewController(abcview, animated: true)
                        self.scannedFaceViews.append(faceView)
                    }
                }
            }
        }

        DispatchQueue.global().async {
            try? VNImageRequestHandler(ciImage: image, orientation: self.imageOrientation).perform([detectFaceRequest])
        }
    }

    private func faceFrame(from boundingBox: CGRect) -> CGRect {

        //translate camera frame to frame inside the ARSKView
        let origin = CGPoint(x: boundingBox.minX * sceneView.bounds.width, y: (1 - boundingBox.maxY) * sceneView.bounds.height)
        let size = CGSize(width: boundingBox.width * sceneView.bounds.width, height: boundingBox.height * sceneView.bounds.height)

        return CGRect(origin: origin, size: size)
    }
}

extension FaceDetectionViewController: ARSCNViewDelegate {
    func cropImage(image: CGImage, toRect: CGRect) -> UIImage? {
        // Cropping is available trhough CGGraphics
        let cgImage :CGImage! = image
        let croppedCGImage: CGImage! = cgImage.cropping(to: toRect)

        return UIImage(cgImage: croppedCGImage)
    }
    func convertCIImageToCGImage(inputImage: CIImage) -> CGImage? {
        let context = CIContext(options: nil)
        if let cgImage = context.createCGImage(inputImage, from: inputImage.extent) {
            return cgImage
        }
        return nil
    }
    func crop(imageToCrop:UIImage, toRect rect:CGRect) -> UIImage{

        let imageRef:CGImage = imageToCrop.cgImage!.cropping(to: rect)!
        let cropped:UIImage = UIImage(cgImage:imageRef)
        return cropped
    }
    //implement ARSCNViewDelegate functions for things like error tracking
}

extension UIImage {

    func rotate(radians: CGFloat) -> UIImage {
        let rotatedSize = CGRect(origin: .zero, size: size)
            .applying(CGAffineTransform(rotationAngle: CGFloat(radians)))
            .integral.size
        UIGraphicsBeginImageContext(rotatedSize)
        if let context = UIGraphicsGetCurrentContext() {
            let origin = CGPoint(x: rotatedSize.width / 2.0,
                                 y: rotatedSize.height / 2.0)
            context.translateBy(x: origin.x, y: origin.y)
            context.rotate(by: radians)
            draw(in: CGRect(x: -origin.x, y: -origin.y,
                            width: size.width, height: size.height))
            let rotatedImage = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()

            return rotatedImage ?? self
        }

        return self
}

标签： swiftarkitface-detection