Python OpenCV - ConvexHull錯誤「點不是一個numpy數組，不是一個標量」？

Question

我正在嘗試運行一些凸面圖像處理。基本上我想要做的是關閉一個開放的輪廓。我發現this answer over at the opencv forum，這正是我想要做的。前段時間我開始將代碼從C++轉換爲Python。我成功地轉換了問題的代碼，但答案的代碼給了我比預期更加艱難的時間。

這是我到目前爲止有： 進口CV2 進口numpy的爲NP

def contoursConvexHull(contours): 
    print("contours length = ", len(contours)) 
    print("contours length of first item = ", len(contours[1])) 
    pts = [] 
    for i in range(0, len(contours)): 
     for j in range(0, len(contours[i])): 
      pts.append(contours[i][j]) 

    result = cv2.convexHull(pts) 
    return result 

# Get our image in color mode (1) 
src = cv2.imread("source.png", 1); 

# Convert the color from BGR to Gray 
srcGray = cv2.cvtColor(src, cv2.COLOR_BGR2GRAY) 

# Use Gaussian Blur 
srcBlur = cv2.GaussianBlur(srcGray, (3, 3), 0) 

# ret is the returned value, otsu is an image 
ret, otsu = cv2.threshold(srcBlur, 0, 255, 
          cv2.THRESH_BINARY+cv2.THRESH_OTSU) 

# Use canny 
srcCanny = cv2.Canny(srcBlur, ret, ret*2, 3) 

# im is the output image 
# contours is the contour list 
# I forgot what heirarchy was 
im, contours, heirarchy = cv2.findContours(srcCanny, 
              cv2.RETR_TREE, 
              cv2.CHAIN_APPROX_SIMPLE) 

cv2.drawContours(src, contours, -1, (0, 255, 0), 3) 

ConvexHullPoints = contoursConvexHull(contours) 
cv2.polylines(src, [ConvexHullPoints], True, (0, 255, 255), 2) 


cv2.imshow("Test", src) 

cv2.waitKey(0) 

，當我試圖運行它，它給了我

result = cv2.convexHull(pts) 
TypeError: points is not a numpy array, neither a scalar 

而且我米猜測我正在喂convexHull一個輸入，它想要別的東西。

我在C++上很體面，但我是Python的初學者。我想我可能會做一些錯誤的事情，我將輪廓元素追加到pts列表中？

說實話，我並不十分確定爲什麼我們需要將點追加回新的數組中，似乎沒有任何值操作或重新安排正在進行。

如果任何人都可以幫助我最終將此代碼從C++轉換爲Python，我將不勝感激。

下面是參考C++代碼：

#include "opencv2/imgproc/imgproc.hpp" 
#include "opencv2/highgui/highgui.hpp" 
#include <stdlib.h> 
#include <stdio.h> 

using namespace cv; 
using namespace std; 

vector<Point> contoursConvexHull(vector<vector<Point> > contours) 
{ 
    vector<Point> result; 
    vector<Point> pts; 
    for (size_t i = 0; i< contours.size(); i++) 
     for (size_t j = 0; j< contours[i].size(); j++) 
      pts.push_back(contours[i][j]); 
    convexHull(pts, result); 
    return result; 
} 

int main(int, char** argv) 
{ 
    Mat src, srcGray,srcBlur,srcCanny; 

    src = imread(argv[1], 1); 
    cvtColor(src, srcGray, CV_BGR2GRAY); 
    blur(srcGray, srcBlur, Size(3, 3)); 

    Canny(srcBlur, srcCanny, 0, 100, 3, true); 

    vector<vector<Point> > contours; 

    findContours(srcCanny, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE); 

    Mat drawing = Mat::zeros(srcCanny.size(), CV_8UC3); 

    for (int i = 0; i< contours.size(); i++) 
    { 
     Scalar color = Scalar(255,255,255); 
     drawContours(drawing, contours, i, color, 2); 
    } 

    vector<Point> ConvexHullPoints = contoursConvexHull(contours); 

    polylines(drawing, ConvexHullPoints, true, Scalar(0,0,255), 2); 
    imshow("Contours", drawing); 

    polylines(src, ConvexHullPoints, true, Scalar(0,0,255), 2); 
    imshow("contoursConvexHull", src); 
    waitKey(); 
    return 0; 
} 

Answer 1

錯誤說pts不是numpy的陣列;其python list。

要轉換pts到一個數組，進口numpy的和做簡單的換算：

import numpy as np 

# code .... 

pts = np.array(pts) 
result = cv2.convexHull(pts)