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insightface/SSH/rcnn/processing/generate_anchor.py
2018-07-09 14:31:13 +08:00

97 lines
2.8 KiB
Python

"""
Generate base anchors on index 0
"""
from __future__ import print_function
import sys
#from builtins import range
import numpy as np
from ..cython.anchors import anchors_cython
def anchors_plane(feat_h, feat_w, stride, base_anchor):
return anchors_cython(feat_h, feat_w, stride, base_anchor)
def generate_anchors(base_size=16, ratios=[0.5, 1, 2],
scales=2 ** np.arange(3, 6)):
"""
Generate anchor (reference) windows by enumerating aspect ratios X
scales wrt a reference (0, 0, 15, 15) window.
"""
base_anchor = np.array([1, 1, base_size, base_size]) - 1
ratio_anchors = _ratio_enum(base_anchor, ratios)
anchors = np.vstack([_scale_enum(ratio_anchors[i, :], scales)
for i in range(ratio_anchors.shape[0])])
return anchors
def generate_anchors_fpn(base_size=[64,32,16,8,4], ratios=[0.5, 1, 2],
scales=8):
"""
Generate anchor (reference) windows by enumerating aspect ratios X
scales wrt a reference (0, 0, 15, 15) window.
"""
anchors = []
_ratios = ratios.reshape( (len(base_size), -1) )
_scales = scales.reshape( (len(base_size), -1) )
for i,bs in enumerate(base_size):
__ratios = _ratios[i]
__scales = _scales[i]
#print('anchors_fpn', bs, __ratios, __scales, file=sys.stderr)
r = generate_anchors(bs, __ratios, __scales)
#print('anchors_fpn', r.shape, file=sys.stderr)
anchors.append(r)
return anchors
def _whctrs(anchor):
"""
Return width, height, x center, and y center for an anchor (window).
"""
w = anchor[2] - anchor[0] + 1
h = anchor[3] - anchor[1] + 1
x_ctr = anchor[0] + 0.5 * (w - 1)
y_ctr = anchor[1] + 0.5 * (h - 1)
return w, h, x_ctr, y_ctr
def _mkanchors(ws, hs, x_ctr, y_ctr):
"""
Given a vector of widths (ws) and heights (hs) around a center
(x_ctr, y_ctr), output a set of anchors (windows).
"""
ws = ws[:, np.newaxis]
hs = hs[:, np.newaxis]
anchors = np.hstack((x_ctr - 0.5 * (ws - 1),
y_ctr - 0.5 * (hs - 1),
x_ctr + 0.5 * (ws - 1),
y_ctr + 0.5 * (hs - 1)))
return anchors
def _ratio_enum(anchor, ratios):
"""
Enumerate a set of anchors for each aspect ratio wrt an anchor.
"""
w, h, x_ctr, y_ctr = _whctrs(anchor)
size = w * h
size_ratios = size / ratios
ws = np.round(np.sqrt(size_ratios))
hs = np.round(ws * ratios)
anchors = _mkanchors(ws, hs, x_ctr, y_ctr)
return anchors
def _scale_enum(anchor, scales):
"""
Enumerate a set of anchors for each scale wrt an anchor.
"""
w, h, x_ctr, y_ctr = _whctrs(anchor)
ws = w * scales
hs = h * scales
anchors = _mkanchors(ws, hs, x_ctr, y_ctr)
return anchors