iOS AVFoundation實現(xiàn)人臉識別

上一篇有介紹了設(shè)置session時添加輸入輸出設(shè)備,實現(xiàn)人臉設(shè)別也比較簡單,把獲取到的人臉用在預(yù)覽視圖上用框框圈出來.


#import "THCameraController.h"
#import <AVFoundation/AVFoundation.h>

@interface THCameraController ()<AVCaptureMetadataOutputObjectsDelegate>
@property(nonatomic,strong)AVCaptureMetadataOutput  *metadataOutput;

@end

@implementation THCameraController

- (BOOL)setupSessionOutputs:(NSError **)error {

    self.metadataOutput = [[AVCaptureMetadataOutput alloc]init];
     //為捕捉會話添加設(shè)備
    if ([self.captureSession canAddOutput:self.metadataOutput]){
        [self.captureSession addOutput:self.metadataOutput];
        
        //獲得人臉屬性
        NSArray *metadatObjectTypes = @[AVMetadataObjectTypeFace];
        
        //設(shè)置metadataObjectTypes 指定對象輸出的元數(shù)據(jù)類型雕拼。
        /*
         限制檢查到元數(shù)據(jù)類型集合的做法是一種優(yōu)化處理方法÷芽剩可以減少我們實際感興趣的對象數(shù)量
         支持多種元數(shù)據(jù)。這里只保留對人臉元數(shù)據(jù)感興趣
         */
        self.metadataOutput.metadataObjectTypes = metadatObjectTypes;
        
        //創(chuàng)建主隊列： 因為人臉檢測用到了硬件加速冬阳，而且許多重要的任務(wù)都在主線程中執(zhí)行倘核，所以需要為這次參數(shù)指定主隊列谷浅。
        dispatch_queue_t mainQueue = dispatch_get_main_queue();
        
        
        //通過設(shè)置AVCaptureVideoDataOutput的代理，就能獲取捕獲到一幀一幀數(shù)據(jù)
        [self.metadataOutput setMetadataObjectsDelegate:self queue:mainQueue];
     
        return YES;
    }else
    {
        //報錯
        if (error) {
            NSDictionary *userInfo = @{NSLocalizedDescriptionKey:@"Failed to still image output"};
            
            *error = [NSError errorWithDomain:THCameraErrorDomain code:THCameraErrorFailedToAddOutput userInfo:userInfo];
            
        }
        return NO;
    }

}

//捕捉數(shù)據(jù)
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputMetadataObjects:(NSArray *)metadataObjects
       fromConnection:(AVCaptureConnection *)connection {
    
    //使用循環(huán)局雄，打印人臉數(shù)據(jù)
    for (AVMetadataFaceObject *face in metadataObjects) {
        NSLog(@"Face detected with ID:%li",(long)face.faceID);
        NSLog(@"Face bounds:%@",NSStringFromCGRect(face.bounds));
        
    }
    
    //將元數(shù)據(jù) 傳遞給 THPreviewView.m   將元數(shù)據(jù)轉(zhuǎn)換為layer
    [self.faceDetectionDelegate didDetectFaces:metadataObjects];
}

@end


#import "THPreviewView.h"

@interface THPreviewView ()


@property(nonatomic,strong)CALayer *overlayLayer;

@property(strong,nonatomic)NSMutableDictionary *faceLayers;

@property(nonatomic,strong)AVCaptureVideoPreviewLayer *previewLayer;

@end

@implementation THPreviewView

+ (Class)layerClass {
    //重寫layerClass方法
    return [AVCaptureVideoPreviewLayer class];
}

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self setupView];
    }
    return self;
}

- (id)initWithCoder:(NSCoder *)coder {
    self = [super initWithCoder:coder];
    if (self) {
        [self setupView];
    }
    return self;
}

- (void)setupView {

    //初始化faceLayers屬性  字典
    self.faceLayers = [NSMutableDictionary dictionary];
    
    //設(shè)置videoGravity 使用AVLayerVideoGravityResizeAspectFill 鋪滿整個預(yù)覽層的邊界范圍
    self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    
    //初始化overlayLayer
    self.overlayLayer = [CALayer layer];
    
    //設(shè)置它的frame
    self.overlayLayer.frame = self.bounds;
    
    //子圖層形變 sublayerTransform屬性   Core  Animation動畫
    self.overlayLayer.sublayerTransform = CATransform3DMakePerspective(1000);
    
    //將子圖層添加到預(yù)覽圖層來
    [self.previewLayer addSublayer:self.overlayLayer];
    
}

//會話的get方法
- (AVCaptureSession*)session {

    return self.previewLayer.session;
}


//會話的set方法
- (void)setSession:(AVCaptureSession *)session {

    
    self.previewLayer.session = session;
    

}

//獲得layer
- (AVCaptureVideoPreviewLayer *)previewLayer {

    return (AVCaptureVideoPreviewLayer *)self.layer;
}



//將檢測到的人臉進行可視化
- (void)didDetectFaces:(NSArray *)faces {

    //創(chuàng)建一個本地數(shù)組 保存轉(zhuǎn)換后的人臉數(shù)據(jù)
    NSArray *transformedFaces = [self transformedFacesFromFaces:faces];
    
    //獲取faceLayers的key甥啄，用于確定哪些人移除了視圖并將對應(yīng)的圖層移出界面。
    /*
        支持同時識別10個人臉
     */
    NSMutableArray *lostFaces = [self.faceLayers.allKeys mutableCopy];
    
    //遍歷每個轉(zhuǎn)換的人臉對象
    for (AVMetadataFaceObject *face in transformedFaces) {
        
        //獲取關(guān)聯(lián)的faceID炬搭。這個屬性唯一標(biāo)識一個檢測到的人臉
        NSNumber *faceID = @(face.faceID);
        
        //將對象從lostFaces 移除
        [lostFaces removeObject:faceID];
        
        //拿到當(dāng)前faceID對應(yīng)的layer
        CALayer *layer = self.faceLayers[faceID];
        
        //如果給定的faceID 沒有找到對應(yīng)的圖層
        if (!layer) {
            
            //調(diào)用makeFaceLayer 創(chuàng)建一個新的人臉圖層
            layer = [self makeFaceLayer];
            
            //將新的人臉圖層添加到 overlayLayer上
            [self.overlayLayer addSublayer:layer];
            
            //將layer加入到字典中
            self.faceLayers[faceID] = layer;
            
        }
        
        //設(shè)置圖層的transform屬性 CATransform3DIdentity 圖層默認變化 這樣可以重新設(shè)置之前應(yīng)用的變化
        layer.transform = CATransform3DIdentity;
        
        //圖層的大小 = 人臉的大小
        layer.frame = face.bounds;
        
        //判斷人臉對象是否具有有效的斜傾交蜈漓。
        if (face.hasRollAngle) {
            
            //如果為YES,則獲取相應(yīng)的CATransform3D 值
            CATransform3D t = [self transformForRollAngle:face.rollAngle];
            
            //將它與標(biāo)識變化關(guān)聯(lián)在一起鼻由，并設(shè)置transform屬性
            layer.transform = CATransform3DConcat(layer.transform, t);
        }
        
        
        //判斷人臉對象是否具有有效的偏轉(zhuǎn)角
        if (face.hasYawAngle) {
            
            //如果為YES,則獲取相應(yīng)的CATransform3D 值
            CATransform3D  t = [self transformForYawAngle:face.yawAngle];
            layer.transform = CATransform3DConcat(layer.transform, t);
            
        }
    }
    
    
    //遍歷數(shù)組將剩下的人臉I(yè)D集合從上一個圖層和faceLayers字典中移除
    for (NSNumber *faceID in lostFaces) {
        
        CALayer *layer = self.faceLayers[faceID];
        [layer removeFromSuperlayer];
        [self.faceLayers  removeObjectForKey:faceID];
    }
    
}


//將設(shè)備的坐標(biāo)空間的人臉轉(zhuǎn)換為視圖空間的對象集合
- (NSArray *)transformedFacesFromFaces:(NSArray *)faces {

    NSMutableArray *transformeFaces = [NSMutableArray array];
    
    for (AVMetadataObject *face in faces) {
        
        //將攝像頭的人臉數(shù)據(jù) 轉(zhuǎn)換為 視圖上的可展示的數(shù)據(jù)
        //簡單說：UIKit的坐標(biāo) 與 攝像頭坐標(biāo)系統(tǒng)（0哨查，0）-（1，1）不一樣。所以需要轉(zhuǎn)換
        //轉(zhuǎn)換需要考慮圖層故觅、鏡像霹娄、視頻重力翎苫、方向等因素 在iOS6.0之前需要開發(fā)者自己計算兔院，但iOS6.0后提供方法
        AVMetadataObject *transformedFace = [self.previewLayer transformedMetadataObjectForMetadataObject:face];
        
        //轉(zhuǎn)換成功后，加入到數(shù)組中
        [transformeFaces addObject:transformedFace];
        
        
    }
    
    return transformeFaces;
    
    
    
}

- (CALayer *)makeFaceLayer {

    //創(chuàng)建一個layer
    CALayer *layer = [CALayer layer];
    
    //邊框?qū)挾葹?.0f
    layer.borderWidth = 5.0f;
    
    //邊框顏色為紅色
    layer.borderColor = [UIColor redColor].CGColor;
    
    layer.contents = (id)[UIImage imageNamed:@"551.png"].CGImage;
    
    //返回layer
    return layer;
    
}



//將 RollAngle 的 rollAngleInDegrees 值轉(zhuǎn)換為 CATransform3D
- (CATransform3D)transformForRollAngle:(CGFloat)rollAngleInDegrees {

    //將人臉對象得到的RollAngle 單位“度” 轉(zhuǎn)為Core Animation需要的弧度值
    CGFloat rollAngleInRadians = THDegreesToRadians(rollAngleInDegrees);

    //將結(jié)果賦給CATransform3DMakeRotation x,y,z軸為0谆吴，0倒源，1 得到繞Z軸傾斜角旋轉(zhuǎn)轉(zhuǎn)換
    return CATransform3DMakeRotation(rollAngleInRadians, 0.0f, 0.0f, 1.0f);
    
}


//將 YawAngle 的 yawAngleInDegrees 值轉(zhuǎn)換為 CATransform3D
- (CATransform3D)transformForYawAngle:(CGFloat)yawAngleInDegrees {

    //將角度轉(zhuǎn)換為弧度值
     CGFloat yawAngleInRaians = THDegreesToRadians(yawAngleInDegrees);
    
    //將結(jié)果CATransform3DMakeRotation x,y,z軸為0，-1句狼，0 得到繞Y軸選擇笋熬。
    //由于overlayer 需要應(yīng)用sublayerTransform，所以圖層會投射到z軸上腻菇，人臉從一側(cè)轉(zhuǎn)向另一側(cè)會有3D 效果
    CATransform3D yawTransform = CATransform3DMakeRotation(yawAngleInRaians, 0.0f, -1.0f, 0.0f);
    
    //因為應(yīng)用程序的界面固定為垂直方向胳螟，但需要為設(shè)備方向計算一個相應(yīng)的旋轉(zhuǎn)變換
    //如果不這樣，會造成人臉圖層的偏轉(zhuǎn)效果不正確
    return CATransform3DConcat(yawTransform, [self orientationTransform]);
}

- (CATransform3D)orientationTransform {

    CGFloat angle = 0.0;
    //拿到設(shè)備方向
    switch ([UIDevice currentDevice].orientation) {
            
            //方向：下
        case UIDeviceOrientationPortraitUpsideDown:
            angle = M_PI;
            break;
            
            //方向：右
        case UIDeviceOrientationLandscapeRight:
            angle = -M_PI / 2.0f;
            break;
        
            //方向：左
        case UIDeviceOrientationLandscapeLeft:
            angle = M_PI /2.0f;
            break;

            //其他
        default:
            angle = 0.0f;
            break;
    }
    
    return CATransform3DMakeRotation(angle, 0.0f, 0.0f, 1.0f);
    
}

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused"


static CGFloat THDegreesToRadians(CGFloat degrees) {

    return degrees * M_PI / 180;
}


static CATransform3D CATransform3DMakePerspective(CGFloat eyePosition) {
    
    
    //CATransform3D 圖層的旋轉(zhuǎn)筹吐，縮放糖耸，偏移，歪斜和應(yīng)用的透
    //CATransform3DIdentity是單位矩陣丘薛，該矩陣沒有縮放嘉竟，旋轉(zhuǎn)，歪斜洋侨，透視舍扰。該矩陣應(yīng)用到圖層上，就是設(shè)置默認值希坚。
    CATransform3D  transform = CATransform3DIdentity;
    
    
    //透視效果（就是近大遠斜咂弧），是通過設(shè)置m34 m34 = -1.0/D 默認是0.D越小透視效果越明顯
    //D:eyePosition 觀察者到投射面的距離
    transform.m34 = -1.0/eyePosition;
    
    return transform;
    
    
}


#pragma clang diagnostic pop

@end