Renderer.swift

    func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
        
        let node = SCNNode()
        
        if let imageAnchor = anchor as? ARImageAnchor{
            let plane = SCNPlane(width: imageAnchor.referenceImage.physicalSize.width, height: imageAnchor.referenceImage.physicalSize.height)
            plane.firstMaterial?.diffuse.contents = UIColor(cgColor: CIColor.white as! CGColor)
            
            let planeNode =  SCNNode(geometry: plane)
            planeNode.eulerAngles.x = - .pi/2
            node.addChildNode(planeNode)
            
        }
        return node
        
    }