def setup(self, bottom, top)方法: 該方法主要是在創建RoIDataLayer的時候調用,初始化self._name_to_top_map(從blobname 到 blobid的一個映射)。結合_caffe.cpp裏面.def("setup", &Layer<Dtype>::LayerSetUp)
,個人認爲,setup(self, bottom, top)應該還是調用底層的Layer::LayerSetUp方法,同時bottom, top
也分別對應着:const vector<Blob<Dtype>*>& bottom, const vector<Blob<Dtype>*>& top
。
回顧底層的src/Net.cpp文件中,caffe將在Creating Layer,AppendTob 和 AppendBottom完成之後,再調用Layer::SetUp方法來 setting up layer…
def setup(self, bottom, top):
"""Setup the RoIDataLayer."""
# print '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Creating layer input-data'
# parse the layer parameter string, which must be valid YAML
layer_params = yaml.load(self.param_str_)
# 解析prototxt文件中Python Layer的python_param參數
self._num_classes = layer_params['num_classes']
self._name_to_top_map = {}
# print '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ _name_to_top_map'
# data blob: holds a batch of N images, each with 3 channels
idx = 0
# 設定top[0]即‘data’的shape,這樣,即使每次迭代的minibatch中圖片的shape不同,也能保證在前向傳播的
# 時候不發生錯誤,訓練日誌中輸出的Top shape信息也是在這裏設置的。但是每次具體的foward的時候都需要重新reshape top blobs。
top[idx].reshape(cfg.TRAIN.IMS_PER_BATCH, 3,
max(cfg.TRAIN.SCALES), cfg.TRAIN.MAX_SIZE)
self._name_to_top_map['data'] = idx
idx += 1
# 在訓練RPN的時候,cfg.TRAIN.HAS_RPN爲true
if cfg.TRAIN.HAS_RPN:
top[idx].reshape(1, 3)
self._name_to_top_map['im_info'] = idx
idx += 1
top[idx].reshape(1, 4)
self._name_to_top_map['gt_boxes'] = idx
idx += 1
else: # not using RPN
# rois blob: holds R regions of interest, each is a 5-tuple
# (n, x1, y1, x2, y2) specifying an image batch index n and a
# rectangle (x1, y1, x2, y2)
top[idx].reshape(1, 5)
self._name_to_top_map['rois'] = idx
idx += 1
# labels blob: R categorical labels in [0, ..., K] for K foreground
# classes plus background
top[idx].reshape(1)
self._name_to_top_map['labels'] = idx
idx += 1
# 例如,在訓練fast rcnn的時候,cfg.TRAIN.BBOX_REG
if cfg.TRAIN.BBOX_REG:
# bbox_targets blob: R bounding-box regression targets with 4
# targets per class
top[idx].reshape(1, self._num_classes * 4)
self._name_to_top_map['bbox_targets'] = idx
idx += 1
# bbox_inside_weights blob: At most 4 targets per roi are active;
# thisbinary vector sepcifies the subset of active targets
# bbox_inside_weights blob 和 bbox_outside_weights blob 是用在SmoothL1Loss layer
#中
top[idx].reshape(1, self._num_classes * 4)
self._name_to_top_map['bbox_inside_weights'] = idx
idx += 1
top[idx].reshape(1, self._num_classes * 4)
self._name_to_top_map['bbox_outside_weights'] = idx
idx += 1
print 'RoiDataLayer: name_to_top:', self._name_to_top_map
assert len(top) == len(self._name_to_top_map)
def _shuffle_roidb_inds(self): 打亂training roidb的順序
def _shuffle_roidb_inds(self):
"""Randomly permute the training roidb."""
if cfg.TRAIN.ASPECT_GROUPING:
# 將roidb中長寬比近似的圖像放在一起(其實也就2種情況,扁的還是豎的),有利於計算速度(具體的,還不清除)
widths = np.array([r['width'] for r in self._roidb])
heights = np.array([r['height'] for r in self._roidb])
horz = (widths >= heights)
vert = np.logical_not(horz)
horz_inds = np.where(horz)[0]
vert_inds = np.where(vert)[0]
inds = np.hstack((
np.random.permutation(horz_inds),
np.random.permutation(vert_inds)))
inds = np.reshape(inds, (-1, 2))
# permutation隨機打亂,而且返回的元素沒有重複(np.random.choice()中replace=False), 類似功能的函數還有np.random.choice()
row_perm = np.random.permutation(np.arange(inds.shape[0]))
inds = np.reshape(inds[row_perm, :], (-1,))
self._perm = inds
else:
self._perm = np.random.permutation(np.arange(len(self._roidb)))
#當前處理的圖像的索引
self._cur = 0
def _get_next_minibatch_inds(self) 在這個方法中,爲什麼要考慮“self._cur + cfg.TRAIN.IMS_PER_BATCH >= len(self._roidb)” 這是因爲訓練的時候要迭代好幾遍整個訓練集
def _get_next_minibatch_inds(self):
"""Return the roidb indices for the next minibatch."""
if self._cur + cfg.TRAIN.IMS_PER_BATCH >= len(self._roidb):
self._shuffle_roidb_inds()
db_inds = self._perm[self._cur:self._cur + cfg.TRAIN.IMS_PER_BATCH]
self._cur += cfg.TRAIN.IMS_PER_BATCH
return db_inds
def _get_next_minibatch(self)
def _get_next_minibatch(self):
"""Return the blobs to be used for the next minibatch.
If cfg.TRAIN.USE_PREFETCH is True, then blobs will be computed in a
separate process and made available through self._blob_queue.
"""
if cfg.TRAIN.USE_PREFETCH:
return self._blob_queue.get()
else:
db_inds = self._get_next_minibatch_inds()
minibatch_db = [self._roidb[i] for i in db_inds]
# 調用minibatch.py中的get_minibatch方法
return get_minibatch(minibatch_db, self._num_classes)
def forward(self, bottom, top): 前向傳播,這個層的前向傳播只需要進行拷貝就可以了,在不同的階段下,根據各自的prototxt文件定義的網絡結構來拷貝數據;
+ 有一點需要記住的是:在模板類Layer的forward函數裏面,會再次調用調用Reshape()函數,也就是說,即使我們每次迭代每個minibatch裏的圖像(或者特徵)的shape不一致,也沒有關係,因爲在真正調用forward_cpu / forward_gpu 之前都會重新Reshape;SetUp裏面的Reshape只是設置了初始的Top blobs 的shape
def forward(self, bottom, top):
"""Get blobs and copy them into this layer's top blob vector."""
blobs = self._get_next_minibatch()
# 1. 對於stage1_rpn_train.pt文件中,該layer只有3個top blob:'data'、'im_info'、'gt_boxes'
# 2. 對於stage1_fast_rcnn_train.pt文件中,該layer有6個top blob:top: 'data'、
#'rois'、'labels'、'bbox_targets'、'bbox_inside_weights'、'bbox_outside_weights'
for blob_name, blob in blobs.iteritems():
top_ind = self._name_to_top_map[blob_name]
# Reshape net's input blobs 調用Caffe.Blob的reshape方法
# 每次迭代forwad的時候都需要reshape,是因爲每次迭代都需要去取minibatch,即
# _get_next_minibatch, 在train fast-rcnn的時候,每個minibatch所包含的圖像的data,rois,
# labels, bbox_targets等的具體的shape都會有所改變,所以每次迭代都需要reshape top blobs
top[top_ind].reshape(*(blob.shape))
# Copy data into net's input blobs
top[top_ind].data[...] = blob.astype(np.float32, copy=False)
def backward(self, top, propagate_down, bottom):
def backward(self, top, propagate_down, bottom):
"""This layer does not propagate gradients."""
pass
def reshape(self, bottom, top):
def reshape(self, bottom, top):
"""Reshaping happens during the call to forward."""
pass
def set_roidb(self, roidb): 主要工作:1. RoIDataLayer設置roidb,2. 打亂shuffle
def set_roidb(self, roidb):
"""Set the roidb to be used by this layer during training."""
# self._roidb = roidb,self表示RoIDataLayer的實例對象,而非類 pascal_voc 或者 imdb的實例對象;
# 賦值符號右側的roidb是我們在創建imdb 或者pascal_voc實例對象時設置的,並且在新建SolverWrapper實例
# 之後在其__init__方法中調用self.solver.net.layers[0].set_roidb(roidb) 傳參而來。
self._roidb = roidb
self._shuffle_roidb_inds()
if cfg.TRAIN.USE_PREFETCH:
self._blob_queue = Queue(10)
self._prefetch_process = BlobFetcher(self._blob_queue,
self._roidb,
self._num_classes)
self._prefetch_process.start()
# Terminate the child process when the parent exists
def cleanup():
print 'Terminating BlobFetcher'
self._prefetch_process.terminate()
self._prefetch_process.join()
import atexit
atexit.register(cleanup)