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我想检测对象并使用视觉框架跟踪该对象。我成功地完成了检测对象和一点点跟踪，但跟踪的准确性并不高。

我希望在转换帧时获得更高的准确性，因为它在跟踪对象时经常失去准确性。

请检查以下代码以检测和跟踪对象：

import UIKit 
import AVFoundation
import Vision

class ViewController: UIViewController {

private lazy var captureSession: AVCaptureSession = {
   let session = AVCaptureSession()
   session.sessionPreset = AVCaptureSession.Preset.photo
   guard let backCamera = AVCaptureDevice.default(for: .video),
       let input = try? AVCaptureDeviceInput(device: backCamera) else 
           {
            return session
           }
    session.addInput(input)
    return session
 }()

private lazy var cameraLayer: AVCaptureVideoPreviewLayer = 
AVCaptureVideoPreviewLayer(session: self.captureSession)

private let handler = VNSequenceRequestHandler()
fileprivate var lastObservation: VNDetectedObjectObservation?

lazy var highlightView: UIView = {
    let view = UIView()
    view.layer.borderColor = UIColor.red.cgColor
    view.layer.borderWidth = 4
    view.backgroundColor = .clear
    return view
}()

override func viewDidLoad() {
   super.viewDidLoad()

    view.layer.addSublayer(cameraLayer)
   view.addSubview(highlightView)

   let output = AVCaptureVideoDataOutput()
   output.setSampleBufferDelegate(self, queue: DispatchQueue(label: 
"queue"))
   captureSession.addOutput(output)

   captureSession.startRunning()

   let tapGestureRecognizer = UITapGestureRecognizer(target: self, 
action: #selector(tapAction))
    view.addGestureRecognizer(tapGestureRecognizer)
}

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    cameraLayer.frame = view.bounds
}

   // MARK: - Actions

  @objc private func tapAction(recognizer: UITapGestureRecognizer) {
    highlightView.frame.size = CGSize(width: 120, height: 120)
    highlightView.center = recognizer.location(in: view)

    let originalRect = highlightView.frame
    var convertedRect = 
    cameraLayer.metadataOutputRectConverted(fromLayerRect: 
    originalRect)
    convertedRect.origin.y = 1 - convertedRect.origin.y

     lastObservation = VNDetectedObjectObservation(boundingBox: 
     convertedRect)
}

fileprivate func handle(_ request: VNRequest, error: Error?) {
    DispatchQueue.main.async {
        guard let newObservation = request.results?.first as? 
VNDetectedObjectObservation else {
           return
        }
        self.lastObservation = newObservation
        var transformedRect = newObservation.boundingBox
        transformedRect.origin.y = 1 - transformedRect.origin.y
        let convertedRect = 
        self.cameraLayer.layerRectConverted(fromMetadataOutputRect: 
       transformedRect)
        self.highlightView.frame = convertedRect
    }
}
}

 extension ViewController: 
 AVCaptureVideoDataOutputSampleBufferDelegate {

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: 
   CMSampleBuffer, from connection: AVCaptureConnection) {
        guard let pixelBuffer = 
    CMSampleBufferGetImageBuffer(sampleBuffer),
            let observation = lastObservation else {
                return
        } 
        let request = VNTrackObjectRequest(detectedObjectObservation: 
    observation) { [unowned self] request, error in
            self.handle(request, error: error)
       }
       request.trackingLevel = .accurate
        do {
            try handler.perform([request], on: pixelBuffer)
        }
        catch {
            print(error)
        }
       }
       }

任何帮助将不胜感激！！谢谢。

4

1 回答 1

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我不太擅长视觉和核心机器学习，但显然你的代码看起来不错。您可以做的一件事是检查视觉在缓冲区中何时没有得到任何跟踪，如果跟踪请求置信度值降至 0 ，则必须将其属性isLastFrame标记为 true。

  if !trackingRequest.isLastFrame {
      if observation.confidence > 0.7 {
          trackingRequest.inputObservation = observation
      } else {
                trackingRequest.isLastFrame = true
            }
          newTrackingRequests.append(trackingRequest)

   }

这样就很容易找出视觉跟踪请求是丢失了跟踪对象还是只是跟踪了错误的对象。

于 2019-03-22T20:32:59.390 回答