我想可视化用cv2.approxPolyDP()
提取的多边形曲线。以下是我正在使用的图像:
我的代码试图隔离主岛,并定义和绘制等高线近似和等高线外壳。我绘制了绿色的轮廓,红色的近似值:
import numpy as np
import cv2
# load image and shrink - it's massive
img = cv2.imread('../data/UK.png')
img = cv2.resize(img, None,fx=0.25, fy=0.25, interpolation = cv2.INTER_CUBIC)
# get a blank canvas for drawing contour on and convert img to grayscale
canvas = np.zeros(img.shape, np.uint8)
img2gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
# filter out small lines between counties
kernel = np.ones((5,5),np.float32)/25
img2gray = cv2.filter2D(img2gray,-1,kernel)
# threshold the image and extract contours
ret,thresh = cv2.threshold(img2gray,250,255,cv2.THRESH_BINARY_INV)
im2,contours,hierarchy = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)
# find the main island (biggest area)
cnt = contours[0]
max_area = cv2.contourArea(cnt)
for cont in contours:
if cv2.contourArea(cont) > max_area:
cnt = cont
max_area = cv2.contourArea(cont)
# define main island contour approx. and hull
perimeter = cv2.arcLength(cnt,True)
epsilon = 0.01*cv2.arcLength(cnt,True)
approx = cv2.approxPolyDP(cnt,epsilon,True)
hull = cv2.convexHull(cnt)
# cv2.isContourConvex(cnt)
cv2.drawContours(canvas, cnt, -1, (0, 255, 0), 3)
cv2.drawContours(canvas, approx, -1, (0, 0, 255), 3)
## cv2.drawContours(canvas, hull, -1, (0, 0, 255), 3) # only displays a few points as well.
cv2.imshow("Contour", canvas)
k = cv2.waitKey(0)
if k == 27: # wait for ESC key to exit
cv2.destroyAllWindows()
以下是生成的图像:
第一幅图像以绿色绘制轮廓。第二个以红色绘制近似值-如何将此近似值绘制为连续闭合曲线
documentation不是很清楚,tutorial也不是很清楚,但我的理解是cv2.approxPolyDP()
应该定义一条连续的闭合曲线,我应该能够用cv2.drawContours()
绘制它。对吗?如果是,我做错了什么
问题只存在于可视化中:
drawContours
需要轮廓的数组(在python中是列表),而不仅仅是一个numpy数组(从approxPolyDP
返回)解决方案如下:更换
到
相关问题 更多 >
编程相关推荐