42 lines
1.3 KiB
Python
42 lines
1.3 KiB
Python
import numpy as np
|
|
|
|
def sample_points_from_masks(masks, num_points):
|
|
"""
|
|
sample points from masks and return its absolute coordinates
|
|
|
|
Args:
|
|
masks: np.array with shape (n, h, w)
|
|
num_points: int
|
|
|
|
Returns:
|
|
points: np.array with shape (n, points, 2)
|
|
"""
|
|
n, h, w = masks.shape
|
|
points = []
|
|
|
|
for i in range(n):
|
|
# find the valid mask points
|
|
indices = np.argwhere(masks[i] == 1)
|
|
# the output format of np.argwhere is (y, x) and the shape is (num_points, 2)
|
|
# we should convert it to (x, y)
|
|
indices = indices[:, ::-1] # (num_points, [y x]) to (num_points, [x y])
|
|
|
|
# import pdb; pdb.set_trace()
|
|
if len(indices) == 0:
|
|
# if there are no valid points, append an empty array
|
|
points.append(np.array([]))
|
|
continue
|
|
|
|
# resampling if there's not enough points
|
|
if len(indices) < num_points:
|
|
sampled_indices = np.random.choice(len(indices), num_points, replace=True)
|
|
else:
|
|
sampled_indices = np.random.choice(len(indices), num_points, replace=False)
|
|
|
|
sampled_points = indices[sampled_indices]
|
|
points.append(sampled_points)
|
|
|
|
# convert to np.array
|
|
points = np.array(points, dtype=np.float32)
|
|
return points
|