ios - 如何从 AVDepthData 缓冲区读取 CGPoint 处的深度数据

Question

我试图在捕获的图像中的某个点找到深度数据，并返回以 米 为单位的距离。

我已启用深度数据并在图像旁边捕获数据。我从图像中心的 X、Y 坐标(以及按下时)获取点，并使用

将其转换为缓冲区索引

Int((width - touchPoint.x) * (height - touchPoint.y))

WIDTH 和 HEIGHT 是捕获图像的尺寸。不过，我不确定这是否是实现此目标的正确方法。

我这样处理深度数据:

func handlePhotoDepthCalculation(point : Int) {

    guard let depth = self.photo else {
        return
    }

    //
    // Convert Disparity to Depth
    //
    let depthData = (depth.depthData as AVDepthData!).converting(toDepthDataType: kCVPixelFormatType_DepthFloat32)
    let depthDataMap = depthData.depthDataMap //AVDepthData -> CVPixelBuffer

    //
    // Set Accuracy feedback
    //
    let accuracy = depthData.depthDataAccuracy
    switch (accuracy) {
    case .absolute:
        /* 
        NOTE - Values within the depth map are absolutely 
        accurate within the physical world.
        */
        self.accuracyLbl.text = "Absolute"
        break
    case .relative:
        /* 
        NOTE - Values within the depth data map are usable for 
        foreground/background separation, but are not absolutely 
        accurate in the physical world. iPhone always produces this.
        */
        self.accuracyLbl.text = "Relative"
    }

    //
    // We convert the data
    //
    CVPixelBufferLockBaseAddress(depthDataMap, CVPixelBufferLockFlags(rawValue: 0))
    let depthPointer = unsafeBitCast(CVPixelBufferGetBaseAddress(depthDataMap), to: UnsafeMutablePointer<Float32>.self)

    //
    // Get depth value for image center
    //
    let distanceAtXYPoint = depthPointer[point]

    //
    // Set UI
    //
    self.distanceLbl.text = "\(distanceAtXYPoint) m" //Returns distance in meters?
    self.filteredLbl.text = "\(depthData.isDepthDataFiltered)" 
}

我不相信我得到了正确的位置。从我的研究来看，精度似乎只在 .relative 或 .absolute 中返回，而不是 float /整数？

Answer 1

要访问 CGPoint 的深度数据，请执行以下操作:

let point = CGPoint(35,26)
let width = CVPixelBufferGetWidth(depthDataMap)
let distanceAtXYPoint = depthPointer[Int(point.y * CGFloat(width) + point.x)]

我希望它有用。