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import numpy as np
from shapely.geometry import Polygon
def intersection(g, p):
g = Polygon(g[:8].reshape((4, 2)))
p = Polygon(p[:8].reshape((4, 2)))
if not g.is_valid or not p.is_valid:
return 0
inter = Polygon(g).intersection(Polygon(p)).area
union = g.area + p.area - inter
if union == 0:
return 0
else:
return inter/union
def weighted_merge(g, p):
# g[0]=min(g[0],p[0])
# g[1] = min(g[1], p[1])
# g[4] = max(g[4], p[4])
# g[5]= max(g[5],p[5])
#
# g[2] = max(g[2], p[2])
# g[3] = min(g[3], p[3])
# g[6] = min(g[6], p[6])
# g[7] = max(g[7], p[7])
g[:8] = (g[8] * g[:8] + p[8] * p[:8])/(g[8] + p[8])
g[8] = (g[8] + p[8])
return g
def standard_nms(S, thres):
order = np.argsort(S[:, 8])[::-1]
keep = []
while order.size > 0:
i = order[0]
keep.append(i)
ovr = np.array([intersection(S[i], S[t]) for t in order[1:]])
inds = np.where(ovr <= thres)[0]
order = order[inds+1]
return S[keep]
def nms_locality(polys, thres=0.3):
'''
locality aware nms of EAST
:param polys: a N*9 numpy array. first 8 coordinates, then prob
:return: boxes after nms
'''
S = []
p = None
for g in polys:
if p is not None and intersection(g, p) > thres:
p = weighted_merge(g, p)
else:
if p is not None:
S.append(p)
p = g
if p is not None:
S.append(p)
if len(S) == 0:
return np.array([])
return standard_nms(np.array(S), thres)
if __name__ == '__main__':
# 343,350,448,135,474,143,369,359
print(Polygon(np.array([[343, 350], [448, 135],
[474, 143], [369, 359]])).area)
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