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FIX: fix angle convention

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François Boulogne
2013-10-12 14:09:51 +02:00
parent e9f3bd66ac
commit 7a1b1c28de
2 changed files with 28 additions and 4 deletions
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skimage/transform/_hough_transform.pyx
+8 -1
View File
@@ -206,9 +206,16 @@ def hough_ellipse(cnp.ndarray img, int threshold=4, double accuracy=1,
hist_max = np.max(hist)
if hist_max > threshold:
angle = np.arctan2(p1x - p2x, p1y - p2y)
# pi - angle to keep ellipse_perimeter() convention
# to keep ellipse_perimeter() convention
if angle != 0:
angle = np.pi - angle
# When angle is not in [-pi:pi]
# it would mean in ellipse_perimeter()
# that a < b. But we keep a > b.
if angle > np.pi:
angle = angle - np.pi / 2.
elif angle < - np.pi:
angle = angle + np.pi / 2.
b = sqrt(bin_edges[hist.argmax()])
results.append((x0,
y0,
skimage/transform/tests/test_hough_transform.py
+20 -3
View File
@@ -165,9 +165,9 @@ def test_hough_ellipse_zero_angle():
def test_hough_ellipse_non_zero_angle():
img = np.zeros((30, 20), dtype=int)
img = np.zeros((30, 24), dtype=int)
a = 6
b = 9
b = 12
x0 = 10
y0 = 15
angle = np.pi / 1.35
@@ -176,10 +176,27 @@ def test_hough_ellipse_non_zero_angle():
result = tf.hough_ellipse(img, threshold=15, accuracy=3)
assert_almost_equal(result[0][0] / 100., x0 / 100., decimal=1)
assert_almost_equal(result[0][1] / 100., y0 / 100., decimal=1)
assert_almost_equal(result[0][2] / 100., b / 100., decimal=1)
assert_almost_equal(result[0][2] / 10., b / 10., decimal=1)
assert_almost_equal(result[0][3] / 100., a / 100., decimal=1)
assert_almost_equal(result[0][4], angle, decimal=1)
def test_hough_ellipse_non_zero_angle2():
img = np.zeros((30, 24), dtype=int)
b = 6
a = 12
x0 = 10
y0 = 15
angle = np.pi / 1.35
rr, cc = ellipse_perimeter(y0, x0, b, a, orientation=angle)
img[rr, cc] = 1
result = tf.hough_ellipse(img, threshold=15, accuracy=3)
assert_almost_equal(result[0][0] / 100., x0 / 100., decimal=1)
assert_almost_equal(result[0][1] / 100., y0 / 100., decimal=1)
assert_almost_equal(result[0][2] / 100., a / 100., decimal=1)
assert_almost_equal(result[0][3] / 100., b / 100., decimal=1)
assert_almost_equal(result[0][4], angle, decimal=1)
if __name__ == "__main__":
np.testing.run_module_suite()