ios - AVDepthData を手動でビルドする方法

Question

独自の深度マップを作成し、ポートレート写真のような画像を深度情報とともに保存したいと考えています。まず、AVDepthData を生成する必要があります。それがどのように構築されたかを掘り下げた後、私はそれを再現しようとします:

func buildDepth() {
    // ...
    let info: [AnyHashable: Any] = [kCGImagePropertyPixelFormat: kCVPixelFormatType_DisparityFloat32,
                                    kCGImagePropertyWidth: width,
                                    kCGImagePropertyHeight: height,
                                    kCGImagePropertyBytesPerRow: bytesPerRow]
    let metadata = generateMetadata(photo: photo)
    let dic: [AnyHashable: Any] = [kCGImageAuxiliaryDataInfoDataDescription: info,
                                   kCGImageAuxiliaryDataInfoData: data,
                                   kCGImageAuxiliaryDataInfoMetadata: metadata]
    guard let depthData = try? AVDepthData(fromDictionaryRepresentation: dic) else {
        return false
    }
    print(depthData.cameraCalibrationData) // <----- prints nil
}

private static func generateMetadata(photo: Photo) -> CGImageMetadata {
    let metadata = CGImageMetadataCreateMutable()

    let fxy = max(photo.orig.size.width, photo.orig.size.height)
    let cx = photo.orig.size.width/2
    let cy = photo.orig.size.height/2

    addMetadataTag(metadata, key: "Filtered", value: true)
    addMetadataTag(metadata, key: "Quality", value: "high")
    addMetadataTag(metadata, key: "Accuracy", value: "relative")
    addMetadataTag(metadata, key: "DepthDataVersion", value: 65538)
    addMetadataTag(metadata, key: "PixelSize", value: 0.001000)


    addMetadataTag(metadata, key: "LensDistortionCoefficients", value: [0,0,0,0,0,0,0,0])
    addMetadataTag(metadata, key: "InverseLensDistortionCoefficients", value: [0,0,0,0,0,0,0,0])


    addMetadataTag(metadata, key: "IntrinsicMatrixReferenceWidth", value: photo.orig.size.width)
    addMetadataTag(metadata, key: "IntrinsicMatrixReferenceHeight", value: photo.orig.size.height)
    addMetadataTag(metadata, key: "LensDistortionCenterOffsetX", value: cx)
    addMetadataTag(metadata, key: "LensDistortionCenterOffsetY", value: cy)
    addMetadataTag(metadata, key: "ExtrinsicMatrix", value: [1,0,0,
                                                                  0,1,0,
                                                                  0,0,1,
                                                                  0,0,0])

    addMetadataTag(metadata, key: "IntrinsicMatrix", value: [fxy,0,0,
                                                                  0,fxy,0,
                                                                  cx,cy,1])

    addMetadataTag(metadata, type: .depthBlur, key: "SimulatedAperture", value: 4.5)
    addMetadataTag(metadata, type: .depthBlur, key: "RenderingParameters", value: "UkVORAEAAAAwAAAAAgAAAJqZmT4K1yM8F0iSOTVeuj0zM7M/DdXOOwAAAD+amRk+")
    print(metadata)
    return metadata
}

enum MetadataType {
    case depth, depthBlur
}

@discardableResult private static func addMetadataTag(_ metadata: CGMutableImageMetadata, type: MetadataType = .depth, key: String, value: Any) -> Bool {
    let namespace: String
    let prefix: String
    switch type {
    case .depth:
        namespace = "http://ns.apple.com/depthData/1.0/"
        prefix = "depthData"
    case .depthBlur:
        namespace = "http://ns.apple.com/depthBlurEffect/1.0/"
        prefix = "depthBlurEffect"
    }
    guard let metadataTag = CGImageMetadataTagCreate(namespace as CFString, prefix as CFString, key as CFString, .default, value as CFTypeRef)
        else { return false }

    print("type", CGImageMetadataTagGetType(metadataTag).rawValue)
    return CGImageMetadataSetTagWithPath(metadata, nil, ("xmp:"+key) as CFString, metadataTag)
}

この後、AVDepthData画像に保存できる魔女を取得します。しかし、このデータには のような追加情報は含まれていませんcameraCalibrationData。システムによって生成された辞書は、私の辞書に似ています。