如何在OpenCV.js中为文档绘制轮廓

Question

我是OpenCV的初学者，在文档图像周围绘制4点轮廓时遇到了一个问题，我遵循了本教程和OpenCV.js 的StackOverflow中的这个例子

得到以下错误：

BindingError {name: "BindingError", message: "Cannot pass "[object Object]" as a MatVector", 
stack: "BindingError: Cannot pass "[object Object]....

不确定如何将我发现的轮廓正确传递给drawContours方法

以下是代码示例：

let color = new cv.Scalar(0, 255, 0);
let edgeDetected = new cv.Mat();
let contours = new cv.MatVector();
let hierarchy = new cv.Mat();
cv.Canny(img, edgeDetected, 100, 200, 3, true);
cv.findContours(edgeDetected, contours, hierarchy, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_NONE);
let foundContour = new cv.MatVector();
//Get area for all contours so we can find the biggest
let sortableContours = [];
for (let i = 0; i < contours.size(); i++) {
let cnt = contours.get(i);
let area = cv.contourArea(cnt, false);
let perim = cv.arcLength(cnt, false);
sortableContours.push({ areaSize: area, perimiterSize: perim, contour: cnt });
}
sortableContours = sortableContours.sort((item1, item2) => { return (item1.areaSize > item2.areaSize) ? -1 : (item1.areaSize < item2.areaSize) ? 1 : 0; }).slice(0, 5);
//Ensure the top area contour has 4 corners (NOTE: This is not a perfect science and likely needs more attention)
let approx = new cv.Mat();
cv.approxPolyDP(sortableContours[0].contour, approx, .05 * sortableContours[0].perimiterSize, true);
if (approx.rows == 4) {
console.log('Found a 4-corner approx');
foundContour = approx;
}
else{
console.log('No 4-corner large contour!');
return;
}
//Find the corners
let corner1 = new cv.Point(foundContour.data32S[0], foundContour.data32S[1]);
let corner2 = new cv.Point(foundContour.data32S[2], foundContour.data32S[3]);
let corner3 = new cv.Point(foundContour.data32S[4], foundContour.data32S[5]);
let corner4 = new cv.Point(foundContour.data32S[6], foundContour.data32S[7]);
//Order the corners
let cornerArray = new cv.MatVector();
cornerArray = [{ corner: corner1 }, { corner: corner2 }, { corner: corner3 }, { corner: corner4 }];
//Sort by Y position (to get top-down)
cornerArray.sort((item1, item2) => { 
return (item1.corner.y < item2.corner.y) ? -1 : (item1.corner.y > item2.corner.y) ? 1 : 0; 
}).slice(0, 5);

for (c of cornerArray) {
cv.drawContours(img, c.corner, -1, color, 1, cv.LINE_8, hierarchy, 100);
}
cv.imshow('canvasOutput', img);

任何帮助都将不胜感激。非常感谢。

Answer 1

我看不出您在哪里初始化了opencv。做这个

const cv = require("./opencv.js");
cv['onRuntimeInitialized']=()=>{
let mat = new cv.Mat();
console.log(mat.size()); //use this line to test if opencv was initialized successfully
mat.delete();
};

从这个片段开始