Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

https://github.com/duzexu/ARuler

Mesure distance using apple ARKit
https://github.com/duzexu/ARuler

apple-arkit arkit mesure-distance ruler scenekit swift

Last synced: 16 days ago
JSON representation

Mesure distance using apple ARKit

Lists

README 

        


  




# ARuler

Mesure distance using apple ARKit



[ENGLISH README](./README_EN.md)



## 预览

  

  

## 运行

cd到工程目录下，运行`pod install`



## 安装

因为ARKit使用限制，设备要求为6s以上，系统最低要求为iOS11，Xcode版本为9以上



测量时需保证光线充足



## 问题

ARKit目前只能识别水平的平面，所以只能测量水平面的长度，不能测量垂直平面上的长度，不知道视频里的是怎么实现的，有知道的小伙伴可以一起交流一下



去除了识别平面后才进行测量的逻辑，采用最近的特征点，可以测量垂直的物体啦



## 说明

项目中确定起始和结束点的位置主要有以下几种



##### 如果存在检测到的平面，返回平面上一点



```

let planeHitTestResults = sceneView.hitTest(position, types: .existingPlaneUsingExtent)

    if let result = planeHitTestResults.first {



        let planeHitTestPosition = SCNVector3.positionFromTransform(result.worldTransform)

        let planeAnchor = result.anchor



        // Return immediately - this is the best possible outcome.

        return (planeHitTestPosition, planeAnchor as? ARPlaneAnchor, true)

    }

```



##### 根据当前ARFrame中的rawFeaturePoints计算点



* 获取以摄像头和屏幕上一点对应的透视消失点为轴，角度为10度，最小距离为10cm，最大距离为三米组成的截锥体内的特征点



```

let highQualityfeatureHitTestResults = sceneView.hitTestWithFeatures(position, coneOpeningAngleInDegrees: 5, minDistance: 0.1, maxDistance: 3.0)

```



* 假设抽样的特征点符合正态分布，过滤偏差值大于 3σ 的值



```

func fliterWithFeatures(_ features:[FeatureHitTestResult]) -> [SCNVector3] {

    guard features.count >= 3 else {

        return features.map { (featureHitTestResult) -> SCNVector3 in

            return featureHitTestResult.position

        };

    }

        

    var points = features.map { (featureHitTestResult) -> SCNVector3 in

        return featureHitTestResult.position

    }

    // 平均值

    let average = points.average!

    // 方差

    let variance = sqrtf(points.reduce(0) { (sum, point) -> Float in

        var sum = sum

        sum += (point-average).length()*100*(point-average).length()*100

        return sum

        }/Float(points.count-1))

    // 标准差

    let standard = sqrtf(variance)

    let σ = variance/standard

    points = points.filter { (point) -> Bool in

        if (point-average).length()*100 > 3*σ {

            print(point,average)

        }

        return (point-average).length()*100 < 3*σ

    }

    return points

}

```



* 根据过滤的点用[最小二乘法](https://wenku.baidu.com/view/c9d0713710661ed9ac51f305.html)进行平面推定



```

let detectPlane = planeDetectWithFeatureCloud(featureCloud: warpFeatures)

```



* 根据截锥体轴上的点和向量及平面上的点和法向量计算交点



```

var planePoint = SCNVector3Zero

if detectPlane.x != 0 {

	planePoint = SCNVector3(detectPlane.w/detectPlane.x,0,0)

}else if detectPlane.y != 0 {

    planePoint = SCNVector3(0,detectPlane.w/detectPlane.y,0)

}else {

    planePoint = SCNVector3(0,0,detectPlane.w/detectPlane.z)

}

    

let ray = sceneView.hitTestRayFromScreenPos(position)

let crossPoint = planeLineIntersectPoint(planeVector: SCNVector3(detectPlane.x,detectPlane.y,detectPlane.z), planePoint: planePoint, lineVector: ray!.direction, linePoint: ray!.origin)

```



* 如果直线和平面平行或不符合平面推定条件，返回点平均值

* 如果截锥体内没有符合的点，查找出距离轴最近的点



## 参考

看到微博上[AR虚拟尺子视频](https://m.weibo.cn/1652421612/4122791333240092)，就想试着模仿着实现一下



部分代码来自[苹果ARKitDemo](https://developer.apple.com/sample-code/wwdc/2017/PlacingObjects.zip)



平面拟合代码参考这篇[博客](http://blog.csdn.net/zhouyelihua/article/details/46122977)



## 建议

有任何建议或问题请提issue



## 开源协议

ARuler开源在 GPL 协议下，详细请查看 [LICENSE](./LICENSE) 文件