File size: 11,240 Bytes
9a393e2 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 |
# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Keypoint operations.
Keypoints are represented as tensors of shape [num_instances, num_keypoints, 2],
where the last dimension holds rank 2 tensors of the form [y, x] representing
the coordinates of the keypoint.
"""
import numpy as np
import tensorflow as tf
def scale(keypoints, y_scale, x_scale, scope=None):
"""Scales keypoint coordinates in x and y dimensions.
Args:
keypoints: a tensor of shape [num_instances, num_keypoints, 2]
y_scale: (float) scalar tensor
x_scale: (float) scalar tensor
scope: name scope.
Returns:
new_keypoints: a tensor of shape [num_instances, num_keypoints, 2]
"""
with tf.name_scope(scope, 'Scale'):
y_scale = tf.cast(y_scale, tf.float32)
x_scale = tf.cast(x_scale, tf.float32)
new_keypoints = keypoints * [[[y_scale, x_scale]]]
return new_keypoints
def clip_to_window(keypoints, window, scope=None):
"""Clips keypoints to a window.
This op clips any input keypoints to a window.
Args:
keypoints: a tensor of shape [num_instances, num_keypoints, 2]
window: a tensor of shape [4] representing the [y_min, x_min, y_max, x_max]
window to which the op should clip the keypoints.
scope: name scope.
Returns:
new_keypoints: a tensor of shape [num_instances, num_keypoints, 2]
"""
with tf.name_scope(scope, 'ClipToWindow'):
y, x = tf.split(value=keypoints, num_or_size_splits=2, axis=2)
win_y_min, win_x_min, win_y_max, win_x_max = tf.unstack(window)
y = tf.maximum(tf.minimum(y, win_y_max), win_y_min)
x = tf.maximum(tf.minimum(x, win_x_max), win_x_min)
new_keypoints = tf.concat([y, x], 2)
return new_keypoints
def prune_outside_window(keypoints, window, scope=None):
"""Prunes keypoints that fall outside a given window.
This function replaces keypoints that fall outside the given window with nan.
See also clip_to_window which clips any keypoints that fall outside the given
window.
Args:
keypoints: a tensor of shape [num_instances, num_keypoints, 2]
window: a tensor of shape [4] representing the [y_min, x_min, y_max, x_max]
window outside of which the op should prune the keypoints.
scope: name scope.
Returns:
new_keypoints: a tensor of shape [num_instances, num_keypoints, 2]
"""
with tf.name_scope(scope, 'PruneOutsideWindow'):
y, x = tf.split(value=keypoints, num_or_size_splits=2, axis=2)
win_y_min, win_x_min, win_y_max, win_x_max = tf.unstack(window)
valid_indices = tf.logical_and(
tf.logical_and(y >= win_y_min, y <= win_y_max),
tf.logical_and(x >= win_x_min, x <= win_x_max))
new_y = tf.where(valid_indices, y, np.nan * tf.ones_like(y))
new_x = tf.where(valid_indices, x, np.nan * tf.ones_like(x))
new_keypoints = tf.concat([new_y, new_x], 2)
return new_keypoints
def change_coordinate_frame(keypoints, window, scope=None):
"""Changes coordinate frame of the keypoints to be relative to window's frame.
Given a window of the form [y_min, x_min, y_max, x_max], changes keypoint
coordinates from keypoints of shape [num_instances, num_keypoints, 2]
to be relative to this window.
An example use case is data augmentation: where we are given groundtruth
keypoints and would like to randomly crop the image to some window. In this
case we need to change the coordinate frame of each groundtruth keypoint to be
relative to this new window.
Args:
keypoints: a tensor of shape [num_instances, num_keypoints, 2]
window: a tensor of shape [4] representing the [y_min, x_min, y_max, x_max]
window we should change the coordinate frame to.
scope: name scope.
Returns:
new_keypoints: a tensor of shape [num_instances, num_keypoints, 2]
"""
with tf.name_scope(scope, 'ChangeCoordinateFrame'):
win_height = window[2] - window[0]
win_width = window[3] - window[1]
new_keypoints = scale(keypoints - [window[0], window[1]], 1.0 / win_height,
1.0 / win_width)
return new_keypoints
def to_normalized_coordinates(keypoints, height, width,
check_range=True, scope=None):
"""Converts absolute keypoint coordinates to normalized coordinates in [0, 1].
Usually one uses the dynamic shape of the image or conv-layer tensor:
keypoints = keypoint_ops.to_normalized_coordinates(keypoints,
tf.shape(images)[1],
tf.shape(images)[2]),
This function raises an assertion failed error at graph execution time when
the maximum coordinate is smaller than 1.01 (which means that coordinates are
already normalized). The value 1.01 is to deal with small rounding errors.
Args:
keypoints: A tensor of shape [num_instances, num_keypoints, 2].
height: Maximum value for y coordinate of absolute keypoint coordinates.
width: Maximum value for x coordinate of absolute keypoint coordinates.
check_range: If True, checks if the coordinates are normalized.
scope: name scope.
Returns:
tensor of shape [num_instances, num_keypoints, 2] with normalized
coordinates in [0, 1].
"""
with tf.name_scope(scope, 'ToNormalizedCoordinates'):
height = tf.cast(height, tf.float32)
width = tf.cast(width, tf.float32)
if check_range:
max_val = tf.reduce_max(keypoints)
max_assert = tf.Assert(tf.greater(max_val, 1.01),
['max value is lower than 1.01: ', max_val])
with tf.control_dependencies([max_assert]):
width = tf.identity(width)
return scale(keypoints, 1.0 / height, 1.0 / width)
def to_absolute_coordinates(keypoints, height, width,
check_range=True, scope=None):
"""Converts normalized keypoint coordinates to absolute pixel coordinates.
This function raises an assertion failed error when the maximum keypoint
coordinate value is larger than 1.01 (in which case coordinates are already
absolute).
Args:
keypoints: A tensor of shape [num_instances, num_keypoints, 2]
height: Maximum value for y coordinate of absolute keypoint coordinates.
width: Maximum value for x coordinate of absolute keypoint coordinates.
check_range: If True, checks if the coordinates are normalized or not.
scope: name scope.
Returns:
tensor of shape [num_instances, num_keypoints, 2] with absolute coordinates
in terms of the image size.
"""
with tf.name_scope(scope, 'ToAbsoluteCoordinates'):
height = tf.cast(height, tf.float32)
width = tf.cast(width, tf.float32)
# Ensure range of input keypoints is correct.
if check_range:
max_val = tf.reduce_max(keypoints)
max_assert = tf.Assert(tf.greater_equal(1.01, max_val),
['maximum keypoint coordinate value is larger '
'than 1.01: ', max_val])
with tf.control_dependencies([max_assert]):
width = tf.identity(width)
return scale(keypoints, height, width)
def flip_horizontal(keypoints, flip_point, flip_permutation, scope=None):
"""Flips the keypoints horizontally around the flip_point.
This operation flips the x coordinate for each keypoint around the flip_point
and also permutes the keypoints in a manner specified by flip_permutation.
Args:
keypoints: a tensor of shape [num_instances, num_keypoints, 2]
flip_point: (float) scalar tensor representing the x coordinate to flip the
keypoints around.
flip_permutation: rank 1 int32 tensor containing the keypoint flip
permutation. This specifies the mapping from original keypoint indices
to the flipped keypoint indices. This is used primarily for keypoints
that are not reflection invariant. E.g. Suppose there are 3 keypoints
representing ['head', 'right_eye', 'left_eye'], then a logical choice for
flip_permutation might be [0, 2, 1] since we want to swap the 'left_eye'
and 'right_eye' after a horizontal flip.
scope: name scope.
Returns:
new_keypoints: a tensor of shape [num_instances, num_keypoints, 2]
"""
with tf.name_scope(scope, 'FlipHorizontal'):
keypoints = tf.transpose(keypoints, [1, 0, 2])
keypoints = tf.gather(keypoints, flip_permutation)
v, u = tf.split(value=keypoints, num_or_size_splits=2, axis=2)
u = flip_point * 2.0 - u
new_keypoints = tf.concat([v, u], 2)
new_keypoints = tf.transpose(new_keypoints, [1, 0, 2])
return new_keypoints
def flip_vertical(keypoints, flip_point, flip_permutation, scope=None):
"""Flips the keypoints vertically around the flip_point.
This operation flips the y coordinate for each keypoint around the flip_point
and also permutes the keypoints in a manner specified by flip_permutation.
Args:
keypoints: a tensor of shape [num_instances, num_keypoints, 2]
flip_point: (float) scalar tensor representing the y coordinate to flip the
keypoints around.
flip_permutation: rank 1 int32 tensor containing the keypoint flip
permutation. This specifies the mapping from original keypoint indices
to the flipped keypoint indices. This is used primarily for keypoints
that are not reflection invariant. E.g. Suppose there are 3 keypoints
representing ['head', 'right_eye', 'left_eye'], then a logical choice for
flip_permutation might be [0, 2, 1] since we want to swap the 'left_eye'
and 'right_eye' after a horizontal flip.
scope: name scope.
Returns:
new_keypoints: a tensor of shape [num_instances, num_keypoints, 2]
"""
with tf.name_scope(scope, 'FlipVertical'):
keypoints = tf.transpose(keypoints, [1, 0, 2])
keypoints = tf.gather(keypoints, flip_permutation)
v, u = tf.split(value=keypoints, num_or_size_splits=2, axis=2)
v = flip_point * 2.0 - v
new_keypoints = tf.concat([v, u], 2)
new_keypoints = tf.transpose(new_keypoints, [1, 0, 2])
return new_keypoints
def rot90(keypoints, scope=None):
"""Rotates the keypoints counter-clockwise by 90 degrees.
Args:
keypoints: a tensor of shape [num_instances, num_keypoints, 2]
scope: name scope.
Returns:
new_keypoints: a tensor of shape [num_instances, num_keypoints, 2]
"""
with tf.name_scope(scope, 'Rot90'):
keypoints = tf.transpose(keypoints, [1, 0, 2])
v, u = tf.split(value=keypoints[:, :, ::-1], num_or_size_splits=2, axis=2)
v = 1.0 - v
new_keypoints = tf.concat([v, u], 2)
new_keypoints = tf.transpose(new_keypoints, [1, 0, 2])
return new_keypoints
|