how to map face contours points on real time face, which we get from Firebase MLKit for iOS

Question

how to map 2D Vision points array to create face map after getting vision points from faceDetector ??

faceDetector.process(visionImage) { features, error in

    guard error == nil, let features = features, !features.isEmpty else {
        return
    }
    for face in faces {
        let frame = face.frame
        if let leftEyeContour = face.contour(ofType: .leftEye) {
            // 2D vision Points array
            let leftEyePoints = leftEyeContour.points
        }
        if let upperLipBottomContour = face.contour(ofType: .upperLipBottom) {
            let upperLipBottomPoints = upperLipBottomContour.points
        }
    }
}