def rect_grid_pyr(response_size,
rf,
search_size,
rect_size,
scales,
name='rect_grid_pyr'):
'''Obtains the rectangles for a translation and scale scoremap.
Args:
response_size -- Dimension of scoremap. (height, width)
rf -- Receptive field of scoremap.
search_size -- Dimension of search image in pixels. (height, width)
rect_size -- Size of rectangle in normalized co-ords in search image. [b, 2]
'''
with tf.name_scope(name) as scope:
# Assert that receptive fields are centered.
receptive_field.assert_center_alignment(search_size, response_size, rf)
# Obtain displacement from center of search image.
# Not necessary to use receptive field offset because it is centered.
disp = displacement_from_center(response_size)
disp = tf.to_float(disp) * rf.stride / search_size
disp = tf.multiply(
tf.expand_dims(disp, -4), # [b, h, w, 2] -> [b, 1, h, w, 2]
expand_dims_n(scales, -1, 3)) # [s] -> [s, 1, 1, 1]
# Get centers of receptive field of each pixel.
centers = 0.5 + disp
rect_size = tf.multiply(
tf.expand_dims(rect_size, -2), # [b, 2] -> [b, 1, 2]
tf.expand_dims(scales, -1)) # [s] -> [s, 1]
rect_size = expand_dims_n(rect_size, -2,
2) # [b, s, 2] -> [b, s, 1, 1, 2]
return geom.make_rect_center_size(centers, rect_size)
def _clip_rect_size(rect, min_size=None, max_size=None, name='clip_rect_size'):
with tf.name_scope(name) as scope:
center, size = geom.rect_center_size(rect)
if max_size is not None:
size = tf.minimum(size, max_size)
if min_size is not None:
size = tf.maximum(size, min_size)
return geom.make_rect_center_size(center, size)
def _rect_translate_scale(rect, translate, scale, name='rect_translate_scale'):
'''
Args:
rect: [..., 4]
translate: [..., 2]
scale: [..., 1]
'''
with tf.name_scope(name) as scope:
center, size = geom.rect_center_size(rect)
return geom.make_rect_center_size(center + translate, size * scale)
def modify_aspect_ratio(rect, method='stretch', axis=-1, eps=1e-3, name='modify_aspect_ratio'):
if method == 'stretch':
return rect # No change.
with tf.name_scope(name) as scope:
center, size = geom.rect_center_size(rect)
with tf.control_dependencies([tf.assert_non_negative(size)]):
size = tf.identity(size)
size = tf.maximum(size, eps)
width = scalar_size(size, method, axis=axis, keepdims=True)
return geom.make_rect_center_size(center, width)