ios - ARKit ARCamera 变换错误地顺时针旋转 90 度

Question

我正在关注 ARKit 上的一个较旧的 WWDC 视频: https://developer.apple.com/videos/play/wwdc2017/602/

在此视频中，他们创建了一个 AR 应用程序，该应用程序监听点击手势并使用场景 View 的快照创建图像平面。

这是视频中的相关代码:

但是，当我在我的设备上运行代码时，生成的平面总是相对于我的设备方向顺时针旋转 90 度。例如，当我的设备处于纵向模式时，生成的平面如下所示:

同样，如果我以横向右手方向握住设备，图像平面的“顶部”将指向下方。

ARCamera 转换似乎总是相对于设备方向偏离 90 度，这是有原因的吗？

Answer 1

By default, image captured by iPhone or iPad's camera is encoded in the camera sensor's native landscape orientation. When you make a snapshot (even if your device is in portrait orientation), iOS writes an orientation value of:

CGImagePropertyOrientation.right

in the resulting image file. ARKit app reads this value from the file's metadata and then displays the image applying a 90° ClockWise rotation, so your captured image appears in the intended photographer's orientation.

您需要应用相反的操作——旋转图像 90° CounterClockWise。

因此，请阅读 this post 以了解如何使用 CVPixelBuffer 进行制作。

此外，以下扩展方法也可以帮助您:

extension CGImagePropertyOrientation {

    init(_ uiOrientation: UIImage.Orientation) {

        switch uiOrientation {
            case .up: self = .up
            case .upMirrored: self = .upMirrored
            case .down: self = .down
            case .downMirrored: self = .downMirrored
            case .left: self = .left
            case .leftMirrored: self = .leftMirrored
            case .right: self = .right
            case .rightMirrored: self = .rightMirrored
            @unknown default: fatalError()
        }
    }
} 
extension UIImage.Orientation {

    init(_ cgOrientation: UIImage.Orientation) {

        switch cgOrientation {
            case .up: self = .up
            case .upMirrored: self = .upMirrored
            case .down: self = .down
            case .downMirrored: self = .downMirrored
            case .left: self = .left
            case .leftMirrored: self = .leftMirrored
            case .right: self = .right
            case .rightMirrored: self = .rightMirrored
            @unknown default: fatalError()
        }
    }
}