ios - ARKit 2 - 裁剪识别图像

Question

所以，我的目标是:

1. 查找已知图像

   guard let referenceImages = ARReferenceImage.referenceImages(inGroupNamed: "AR Resources", bundle: nil) else { return }
   
   let configuration = ARWorldTrackingConfiguration()
   configuration.detectionImages = referenceImages
   

.

从 sceneView 中拍摄快照

 func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {

       let image = sceneView.snapshot()  //  or else self.sceneView.session.currentFrame?.capturedImage

我需要从 SceneView 中提取图像。

这是我的代码， 我正在使用 renderer.projectPoint 方法。

  guard let imageAnchor = anchor as? ARImageAnchor else {
            return
        }
        let posx = anchorTr.x// fnode.convertPosition(node.position, to: node).x //self.positionFromTransform(node.simdTransform).x// node.simdTransform.columns.3.x
        let posy = anchorTr.y//fnode.convertPosition(node.position, to: node).y //self.positionFromTransform(node.simdTransform).y//node.simdTransform.columns.3.y
        let posz = anchorTr.z //node.simdTransform.columns.3.z


                  let width = referenceImage.physicalSize.width
        let height = referenceImage.physicalSize.height


        let topLeftPosition = SCNVector3(posx - Float(width / 2), posy - Float(height / 2), posz )
        let topRightPosition = SCNVector3(posx + Float(width / 2), posy - Float(height / 2), posz )
        let bottomLeftPosition = SCNVector3(posx - Float(width / 2), posy + Float(height / 2), posz )
        let bottomRightPosition = SCNVector3(posx + Float(width / 2), posy  + Float(height / 2), posz)


        let topLeftProjection = renderer.projectPoint(topLeftPosition)
        let topRightProjection = '''
        let bottomLeftProjection = '''
        let bottomRightProjection = '''

        let topLeft = CGPoint(x: CGFloat(topLeftProjection.x), y: CGFloat( topLeftProjection.y))
        let topRight = ''
        let bottomLeft = ''''''
        let bottomRight = '''


  let points = [topLeft, topRight, bottomRight, bottomLeft]

   self.drawPolygon(points, color:.green)

但是这个方法似乎取决于手机的位置。

Answer 1

就我而言，我通过对每个引用点执行此操作来解决该问题。

let transform = node.simdConvertTransform(node.simdTransform, to: node.parent!)

let x = transform.columns.3.x
let y = transform.columns.3.y
let z = transform.columns.3.z

let position = SCNVector3(x, y, z)
let projection = renderer.projectPoint(position)

let screenPoint =  CGPoint(x: CGFloat(projection.x), y: CGFloat( projection.y))