def __init__(self, iou_loss_type, min_level, max_level, num_scales,
aspect_ratios, anchor_scale, image_size, **kwargs):
super().__init__(**kwargs)
self.iou_loss_type = iou_loss_type
self.input_anchors = anchors.Anchors(min_level, max_level, num_scales,
aspect_ratios, anchor_scale,
image_size)
def __call__(self, params, input_context=None, batch_size=None):
input_anchors = anchors.Anchors(params['min_level'],
params['max_level'],
params['num_scales'],
params['aspect_ratios'],
params['anchor_scale'],
params['image_size'])
anchor_labeler = anchors.AnchorLabeler(input_anchors,
params['num_classes'])
example_decoder = tf_example_decoder.TfExampleDecoder(
include_mask='segmentation' in params['heads'],
regenerate_source_id=params['regenerate_source_id'])
batch_size = batch_size or params['batch_size']
seed = params['tf_random_seed'] if self._debug else None
dataset = tf.data.Dataset.list_files(self._file_pattern,
shuffle=self._is_training,
seed=seed)
if input_context:
dataset = dataset.shard(input_context.num_input_pipelines,
input_context.input_pipeline_id)
# Prefetch data from files.
def _prefetch_dataset(filename):
if params.get('dataset_type', None) == 'sstable':
pass
else:
dataset = tf.data.TFRecordDataset(filename).prefetch(1)
return dataset
dataset = dataset.interleave(_prefetch_dataset,
num_parallel_calls=tf.data.AUTOTUNE)
dataset = dataset.with_options(self.dataset_options)
if self._is_training:
dataset = dataset.shuffle(64, seed=seed)
# Parse the fetched records to input tensors for model function.
# pylint: disable=g-long-lambda
if params.get('dataset_type', None) == 'sstable':
map_fn = lambda key, value: self.dataset_parser(
value, example_decoder, anchor_labeler, params)
else:
map_fn = lambda value: self.dataset_parser(value, example_decoder,
anchor_labeler, params)
# pylint: enable=g-long-lambda
dataset = dataset.map(map_fn, num_parallel_calls=tf.data.AUTOTUNE)
dataset = dataset.prefetch(batch_size)
dataset = dataset.batch(batch_size,
drop_remainder=params['drop_remainder'])
dataset = dataset.map(
lambda *args: self.process_example(params, batch_size, *args))
dataset = dataset.prefetch(tf.data.AUTOTUNE)
if self._is_training:
dataset = dataset.repeat()
if self._use_fake_data:
# Turn this dataset into a semi-fake dataset which always loop at the
# first batch. This reduces variance in performance and is useful in
# testing.
dataset = dataset.take(1).cache().repeat()
return dataset
def tflite_pre_nms(params, cls_outputs, box_outputs):
"""Pre-NMS that is compatible with TFLite's custom NMS op.
For details, see tensorflow/lite/kernels/detection_postprocess.cc
Args:
params: a dict of parameters.
cls_outputs: a list of tensors for classes, each tensor denotes a level of
logits with shape [1, H, W, num_class * num_anchors].
box_outputs: a list of tensors for boxes, each tensor ddenotes a level of
boxes with shape [1, H, W, 4 * num_anchors]. Each box format is [y_min,
x_min, y_max, x_man].
Returns:
boxes: boxes encoded as {y_center, x_center, height, width}
scores: scores converted from `cls_outputs` logits using sigmoid
anchors: normalized anchors encoded as {y_center, x_center, height, width}
"""
cls_outputs = to_list(cls_outputs)
box_outputs = to_list(box_outputs)
cls_outputs, box_outputs = merge_class_box_level_outputs(
params, cls_outputs, box_outputs)
eval_anchors = anchors.Anchors(params['min_level'], params['max_level'],
params['num_scales'],
params['aspect_ratios'],
params['anchor_scale'],
params['image_size'])
# TODO(b/175166514): Consider computing Top-K boxes & anchors here. We don't
# do this currently since the resultant graph does not support TFLite
# delegates well. `topk_class_boxes` won't work as-is, since the outputs
# will need to be modified appropriately for TFLite op's consumption.
# TFLite's object detection APIs require normalized anchors.
height, width = utils.parse_image_size(params['image_size'])
normalize_factor = tf.constant([height, width, height, width],
dtype=tf.float32)
normalized_anchors = eval_anchors.boxes / normalize_factor
decoded_anchors = anchors.decode_anchors_to_centersize(
box_outputs, normalized_anchors)
# convert logits to scores.
scores = tf.math.sigmoid(cls_outputs)
return box_outputs, scores, decoded_anchors
def pre_nms(params, cls_outputs, box_outputs, topk=True):
"""Detection post processing before nms.
It takes the multi-level class and box predictions from network, merge them
into unified tensors, and compute boxes, scores, and classes.
Args:
params: a dict of parameters.
cls_outputs: a list of tensors for classes, each tensor denotes a level of
logits with shape [N, H, W, num_class * num_anchors].
box_outputs: a list of tensors for boxes, each tensor ddenotes a level of
boxes with shape [N, H, W, 4 * num_anchors].
topk: if True, select topk before nms (mainly to speed up nms).
Returns:
A tuple of (boxes, scores, classes).
"""
# get boxes by apply bounding box regression to anchors.
eval_anchors = anchors.Anchors(params['min_level'], params['max_level'],
params['num_scales'],
params['aspect_ratios'],
params['anchor_scale'],
params['image_size'])
cls_outputs, box_outputs = merge_class_box_level_outputs(
params, cls_outputs, box_outputs)
if topk:
# select topK purely based on scores before NMS, in order to speed up nms.
cls_outputs, box_outputs, classes, indices = topk_class_boxes(
params, cls_outputs, box_outputs)
anchor_boxes = tf.gather(eval_anchors.boxes, indices)
else:
anchor_boxes = eval_anchors.boxes
classes = None
boxes = anchors.decode_box_outputs(box_outputs, anchor_boxes)
# convert logits to scores.
scores = tf.math.sigmoid(cls_outputs)
return boxes, scores, classes
