我正在尝试使用 Open CV 绘制圆弧,使用 cv2.ellipse 函数
我尝试阅读相同的文档,但我发现它非常令人困惑。在我的例子中它是一个圆弧,所以axes_x和axes_y是相同的,即半径。我的轴应该是什么,我应该在哪个方向计算开始和结束角度?这个旋转角度是多少?
给定的是函数 -cv2.ellipse(img, center, axes, angle, startAngle, endAngle, color[, thickness[, lineType[, shift]]])
import cv2
import numpy as np
def create_blank(height, width, color):
blank_image = np.zeros((int(height), int(width), 3), np.uint8)
blank_image[:, :] = color
return blank_image
def draw_arc(image):
height, width = image.shape[0:2]
# Ellipse parameters
radius = 100
center = (width / 2, height/2)
axes = (radius, radius)
angle = 0
startAngle = 135
endAngle = 180
cv2.line(image, (0, 150), (300, 150), (0, 0, 0), 2, cv2.CV_AA)
cv2.line(image, (150, 0), (150, 300), (0, 0, 0), 2, cv2.CV_AA)
cv2.ellipse(image, center, axes, angle, startAngle, endAngle, (0, 0, 0), 2, cv2.CV_AA)
cv2.imshow("ellipse", image)
# Create new blank 300x150 white image
width, height = 300, 300
image = create_blank(width, height, color=WHITE)
draw_arc(image)
cv2.waitKey(0)
cv2.destroyAllWindows()
When my startAngle is 135 and endAngle is 180, the result looks like
whereas when the startAngle is 0 and endAngle is 90, the result looks like
所以这让人很困惑,弧线是朝哪个方向旋转的。