ARKit

Question

我正在创建一个锚点并将其添加到我的 ARSKView 中，位于相机前方一定距离处，如下所示：

func displayToken(distance: Float) {
        print("token dropped at: \(distance)")
        guard let sceneView = self.view as? ARSKView else {
            return
        }

        // Create anchor using the camera's current position
        if let currentFrame = sceneView.session.currentFrame {
            // Create a transform with a translation of x meters in front of the camera
            var translation = matrix_identity_float4x4
            translation.columns.3.z = -distance
            let transform = simd_mul(currentFrame.camera.transform, translation)

            // Add a new anchor to the session
            let anchor = ARAnchor(transform: transform)
            sceneView.session.add(anchor: anchor)
        }
    }

然后像这样为锚点创建节点：

func view(_ view: ARSKView, nodeFor anchor: ARAnchor) -> SKNode? {
        // Create and configure a node for the anchor added to the view's session.
        if let image = tokenImage {
            let texture = SKTexture(image: image)
            let tokenImageNode = SKSpriteNode(texture: texture)
            tokenImageNode.name = "token"
            return tokenImageNode
        } else {
            return nil
        }
    }

效果很好，我看到图像添加到适当的距离。但是，我要做的是计算 anchor/node 在您移动时在相机前面的距离。问题是使用 fabs(cameraZ - anchor.transform.columns.3.z) 计算似乎立即关闭。请看我下面的代码，它在 update() 方法中计算相机和物体之间的距离：

override func update(_ currentTime: TimeInterval) {
        // Called before each frame is rendered
        guard let sceneView = self.view as? ARSKView else {
            return
        }

        if let currentFrame = sceneView.session.currentFrame {
            let cameraZ =  currentFrame.camera.transform.columns.3.z
            for anchor in currentFrame.anchors {
                if let spriteNode = sceneView.node(for: anchor), spriteNode.name == "token", intersects(spriteNode) {
                    // token is within the camera view
                    //print("token is within camera view from update method")
                    print("DISTANCE BETWEEN CAMERA AND TOKEN: \(fabs(cameraZ - anchor.transform.columns.3.z))")
                    print(cameraZ)
                    print(anchor.transform.columns.3.z)
                }
            }
        }
    }

感谢任何帮助以准确获得相机和锚点之间的距离。

Answer 1

这个是给scenekit用的，不过我会把它留在这里。

let end = node.presentation.worldPosition
let start = sceneView.pointOfView?.worldPosition

let dx = (end?.x)! - (start?.x)!
let dy = (end?.y)! - (start?.y)!
let dz = (end?.z)! - (start?.z)!

let distance = sqrt(pow(dx,2)+pow(dy,2)+pow(dz,2))

Answer 2

4x4 变换矩阵的最后一列是平移向量（或相对于父坐标的位置 space），因此您只需减去这些向量即可获得两个变换之间的三维距离。

let anchorPosition = anchor.transforms.columns.3
let cameraPosition = camera.transform.columns.3

// here’s a line connecting the two points, which might be useful for other things
let cameraToAnchor = cameraPosition - anchorPosition
// and here’s just the scalar distance
let distance = length(cameraToAnchor)

您正在做的事情不正确，因为您要减去每个向量的 z 坐标。如果两个点的 x、y 和 z 不同，则仅减去 z 并不能得到距离。

Answer 3

正如@codeman 上面提到的，这是正确的解决方案：

let distance = simd_distance(YOUR_NODE.simdTransform.columns.3, (sceneView.session.currentFrame?.camera.transform.columns.3)!);

Answer 4

3D 距离 - 您可以查看这些实用程序，

class ARSceneUtils {
        /// return the distance between anchor and camera.
        class func distanceBetween(anchor : ARAnchor,AndCamera camera: ARCamera) -> CGFloat {
        let anchorPostion = SCNVector3Make(
            anchor.transform.columns.3.x,
            anchor.transform.columns.3.y,
            anchor.transform.columns.3.z
        )
        let cametaPosition = SCNVector3Make(
            camera.transform.columns.3.x,
            camera.transform.columns.3.y,
            camera.transform.columns.3.z
        )
        return CGFloat(self.calculateDistance(from: cametaPosition , to: anchorPostion))
    }

    /// return the distance between 2 vectors.
    class func calculateDistance(from: SCNVector3, to: SCNVector3) -> Float {
        let x = from.x - to.x
        let y = from.y - to.y
        let z = from.z - to.z
        return sqrtf( (x * x) + (y * y) + (z * z))
    }

}

现在您可以拨打：

guard let camera = session.currentFrame?.camera else { return }
let anchor = // you anchor
let distanceAchorAndCamera = ARSceneUtils.distanceBetween(anchor: anchor, AndCamera: camera)

Answer 5

使用 RealityKit 的方法略有不同。如果您使用的是世界跟踪配置，您的 AnchorEntity 对象符合 HasAnchoring，这会给您一个 target。目标是 AnchoringComponent.Target 的枚举。它有一个案例.world(let transform)。您可以像这样比较您的世界变换与相机的世界变换：

if case let AnchoringComponent.Target.world(transform) = yourAnchorEntity.anchoring.target {
    let theDistance = distance(transform.columns.3, frame.camera.transform.columns.3)
 }

我花了一些时间才弄清楚，但我认为其他可能正在使用 RealityKit 的人可能会从中受益。

ARKit - 从相机到锚点的距离

ARKit - getting distance from camera to anchor

ios

swift