DepthData - Get per-pixel depth data (CVPixelBuffer data analysis)

Question

Now I run AVDepthPhotoFilter that Rendering Depth Deta from a stereo camera of iPhone7Plus.

So, I want to access per-pixel depth data, but, I don’t know how to do it. Please advice.

Answer 1

How to get DepthData and analysis CVPixelBuffer data

1. You need to make sure your AVCapturePhotoSettings() has isDepthDataDeliveryEnabled = true

2. You have to use the function func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?)

   func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
   
       //## Convert Disparity to Depth ##
   
       let depthData = (photo.depthData as AVDepthData!).converting(toDepthDataType: kCVPixelFormatType_DepthFloat32)
       let depthDataMap = depthData.depthDataMap //AVDepthData -> CVPixelBuffer
   
       //## Data Analysis ##
   
       // Useful data
       let width = CVPixelBufferGetWidth(depthDataMap) //768 on an iPhone 7+
       let height = CVPixelBufferGetHeight(depthDataMap) //576 on an iPhone 7+
       CVPixelBufferLockBaseAddress(depthDataMap, CVPixelBufferLockFlags(rawValue: 0))
   
       // Convert the base address to a safe pointer of the appropriate type
       let floatBuffer = unsafeBitCast(CVPixelBufferGetBaseAddress(depthDataMap), to: UnsafeMutablePointer<Float32>.self)
   
       // Read the data (returns value of type Float)
       // Accessible values : (width-1) * (height-1) = 767 * 575
   
       let distanceAtXYPoint = floatBuffer[Int(x * y)]
   
   }
   

If you want more informations about CVPixelBuffer analysis, here is a useful post -> details