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我正在制作线/弧检测算法。我发现了这组讨厌的点：

[(215, 69), (217, 70), (220, 67), (223, 65), (226, 64), (229, 62), (232, 60), (236, 57), ( 239, 56), (242, 54), (245, 52), (248, 50), (251, 48), (254, 47), (257, 45), (260, 43), (264, 40), (267, 39), (270, 37), (273, 35), (276, 33), (279, 31), (282, 29), (285, 28), (288, 26) , (291, 24)]

我需要确定这些是形成一条线还是一条曲线。我绘制了一组，它看起来像这样： 一组绿色点在一条线上

它们清楚地代表一条线。

但是，我尝试了各种测试来确定它们是直线还是曲线。

  1. 我测试了每个点之间的角度是否大致相等。然而，因为线有点曲折，有一些异常点不相等

  2. 我测试了线的任何 3 个连续点的叉积，以检查它们是否共线

    for k in range(0,len(pts-3),1):
cp1=pts[k]
cp2=pts[k+1]
cp3=pts[k+2]
c1,c2,c3= (cp1.x,cp1.y),(cp2.x,cp2.y),(cp3.x,cp3.y)
cros= (p2.x - p1.x)*(p3.y - p1.y) - (p3.x - p1.x)*(p2.y - p1.y)
print(abs(cros))

其中一些具有非常重要的交叉产品。再次因为这条线是我认为的曲折线。

这种曲折的结构让我的算法崩溃了！那么如何确定曲折的曲折线是直线还是曲线？

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1 回答 1

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假设点是根据与线末端的接近程度来排序的，我们可以将每条线的梯度与它们的邻居进行比较，以确定它们是否位于一条线上。渐变的好处是我们可以如何指定一个容差水平来定义一条线是否太偏离而不能被视为该线的一部分。

JS给定点的一个例子是一个多维数组：

function calculateIsLine() {
let startingGradient=getGradientFromPoint(0);//we get a baseline and compare to every other point. If it is for example, inverted or completely off,
//we can confirm it doesn't line up.

console.log("Starting Gradient: "+startingGradient);

for (let i = 0; i < points.length-1; i++) {//ignoring last point as no point after it.
    if(Math.abs(startingGradient-getGradientFromPoint(i))>0.5){//0.5 is our tolerance level
        console.log("Conflicting Point: "+points[i]+" "+getGradientFromPoint(i));

        return false;
    }

}
return true;

}
function getGradientFromPoint(offset){
    return (points[offset+1][1]-points[offset][1])/(points[offset+1][0]-points[offset][0]);//gradient formula

}

工作片段

let points = [];
let pointsString = "[(215, 69), (217, 70), (220, 67), (223, 65), (226, 64), (229, 62), (300, 60), (236, 57), (239, 56), (242, 54), (245, 52), (248, 50), (251, 48), (254, 47), (257, 45), (260, 43), (264, 40), (267, 39), (270, 37), (273, 35), (276, 33), (279, 31), (282, 29), (285, 28), (288, 26), (291, 24)]";

let conflictingPointIndex;

function setup() {
  let canvas = createCanvas(500, 100);
  let arrayPoints = pointsString.split("(");

  arrayPoints.splice(0, 1);

  for (let i = 0; i < arrayPoints.length; i++) {
    arrayPoints[i] = arrayPoints[i].substr(0, arrayPoints[i].indexOf(")")).replace(" ", "");
    let stringPoint = arrayPoints[i].split(",");
    for (let j = 0; j < 2; j++) {
      if (!points[i])
        points[i] = [];
      points[i][j] = parseInt(stringPoint[j]);

    }
  }
  points.sort((p1, p2) => {
    return p1[0] - p2[0];

  });
 // console.log(points);


}
function draw() {
  background(0);
  console.log(calculateIsLine());
  for (let i = 0; i < points.length; i++) {
    if (i === conflictingPointIndex + 1)
      stroke(255, 0, 0);
    else stroke(255);
    point(points[i][0], points[i][1]);
  }
  noLoop();

}

function calculateIsLine() {
  let startingGradient = getGradientFromPoint(0); //we get a baseline and compare to every other point. If it is for example, inverted or completely off,
  //we can confirm it doesn't line up.
  console.log("Starting Gradient: " + startingGradient);
  for (let i = 0; i < points.length - 1; i++) { //ignoring last point as no point after it.
    if (Math.abs(startingGradient - getGradientFromPoint(i)) > 1.6) { //0.5 is our tolerance level
      console.log("Conflicting Point: " + points[i] + " " + getGradientFromPoint(i) + " " + Math.abs(startingGradient - getGradientFromPoint(i)));
      conflictingPointIndex = i;
      return false;
    }

  }
  return true;

}

function getGradientFromPoint(offset) {
  return (points[offset + 1][1] - points[offset][1]) / (points[offset + 1][0] - points[offset][0]); //gradient formula

}
<script src="https://github.com/processing/p5.js/releases/download/0.6.1/p5.js"></script>

我想不出一种用于曲线的方法。但希望您能想到与此类似的方法。其他人也可能有关于曲线的解决方案。

于 2018-06-10T07:19:07.120 回答