CIDetector trackingID从不显示

问题描述

我正在使用OSX Mavericks上的一些面部检测代码，我试图利用CIDetector提供的多个静态函数中的新的（10.8）面部跟踪。

我有基本的面部检测工作正常，像这样：

   - （void）captureOutput：（AVCaptureOutput * ）captureOutput 
 didOutputSampleBuffer：（CMSampleBufferRef）sampleBuffer 
 fromConnection：（AVCaptureConnection *）connection {
 
 CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer（sampleBuffer）; 
 CIImage * image = [CIImage imageWithCVImageBuffer：imageBuffer]; 
 CIDetector * faceDetector = [CIDetector detectorOfType：CIDetectorTypeFace 
 context：nil 
 options：@ {CIDetectorAccuracy：CIDetectorAccuracyHigh，
 CIDetectorTracking：@YES 
} 
 NSArray * features = [faceDetector featuresInImage：image]; 
 for（CIFaceFeature * feature in features）{
 if（feature.hasTrackingID）{
 NSLog（@tracking id：％@，@（feature.trackingID））; 
} 
} 
} 
  

功能列表正确但是trackingID从来不似乎存在。
有谁得到这个工作在小牛？

我在这里看到过类似的问题（）但我没有学到任何新的东西。

对于它值得它似乎在iOS上正常运行。

解决方案

再次，答案证明是非常明显的：我不断地重新初始化CIDetector，这是坏的性能，也有复位其内部跟踪数据每帧的结果。因此，第一次检测到面部总是第一次检测到该特定CIDetector实例的面部。

此外，CIDetector在文档中警告： p>

这个类可以维护许多可能影响性能的状态变量，因此为了获得最佳性能，重用CIDetector实例而不是创建新的实例。，从。

I'm working on some face detection code on OSX Mavericks and I'm trying to take advantage of the newish (as of 10.8) face tracking across multiple stills functionality that CIDetector offers.

I have basic face detection working fine, like so:

- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
       fromConnection:(AVCaptureConnection *)connection {

    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CIImage *image =  [CIImage imageWithCVImageBuffer:imageBuffer];
    CIDetector *faceDetector = [CIDetector detectorOfType:CIDetectorTypeFace
                                                  context:nil
                                                  options:@{ CIDetectorAccuracy : CIDetectorAccuracyHigh,
                                                         CIDetectorTracking : @YES
                                                        }];
    NSArray *features = [faceDetector featuresInImage:image];
    for ( CIFaceFeature *feature in features ) {
        if (feature.hasTrackingID) {
            NSLog(@"tracking id: %@", @(feature.trackingID));
        }
    }
}

The features list does get populated correctly but that trackingID never seems to be present.Has anyone gotten this working on Mavericks? It fails the same way on Mountain Lion.

I have seen a similar question here (CIFaceFeature trackingID is always coming same for multiple faces) but I didn't learn anything new there.

For what it's worth it does seem to function correctly on iOS.

解决方案

I looked at this code again and the answer turned out to be pretty obvious: I was constantly re-initializing the CIDetector, which was bad for performance and also had the consequence of resetting its internal tracking data each frame. So the first time a face was detected was always the first time a face was detected for that particular CIDetector instance.

Also, CIDetector warns about this in the docs:

"This class can maintain many state variables that can impact performance. So for best performance, reuse CIDetector instances instead of creating new ones.", from https://developer.apple.com/library/mac/documentation/CoreImage/Reference/CIDetector_Ref/Reference/Reference.html.

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