tf_text_graph_ssd.py
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# This file is a part of OpenCV project.
# It is a subject to the license terms in the LICENSE file found in the top-level directory
# of this distribution and at http://opencv.org/license.html.
#
# Copyright (C) 2018, Intel Corporation, all rights reserved.
# Third party copyrights are property of their respective owners.
#
# Use this script to get the text graph representation (.pbtxt) of SSD-based
# deep learning network trained in TensorFlow Object Detection API.
# Then you can import it with a binary frozen graph (.pb) using readNetFromTensorflow() function.
# See details and examples on the following wiki page: https://github.com/opencv/opencv/wiki/TensorFlow-Object-Detection-API
import argparse
import re
from math import sqrt
from tf_text_graph_common import *
class SSDAnchorGenerator:
def __init__(self, min_scale, max_scale, num_layers, aspect_ratios,
reduce_boxes_in_lowest_layer, image_width, image_height):
self.min_scale = min_scale
self.aspect_ratios = aspect_ratios
self.reduce_boxes_in_lowest_layer = reduce_boxes_in_lowest_layer
self.image_width = image_width
self.image_height = image_height
self.scales = [min_scale + (max_scale - min_scale) * i / (num_layers - 1)
for i in range(num_layers)] + [1.0]
def get(self, layer_id):
if layer_id == 0 and self.reduce_boxes_in_lowest_layer:
widths = [0.1, self.min_scale * sqrt(2.0), self.min_scale * sqrt(0.5)]
heights = [0.1, self.min_scale / sqrt(2.0), self.min_scale / sqrt(0.5)]
else:
widths = [self.scales[layer_id] * sqrt(ar) for ar in self.aspect_ratios]
heights = [self.scales[layer_id] / sqrt(ar) for ar in self.aspect_ratios]
widths += [sqrt(self.scales[layer_id] * self.scales[layer_id + 1])]
heights += [sqrt(self.scales[layer_id] * self.scales[layer_id + 1])]
min_size = min(self.image_width, self.image_height)
widths = [w * min_size for w in widths]
heights = [h * min_size for h in heights]
return widths, heights
class MultiscaleAnchorGenerator:
def __init__(self, min_level, aspect_ratios, scales_per_octave, anchor_scale):
self.min_level = min_level
self.aspect_ratios = aspect_ratios
self.anchor_scale = anchor_scale
self.scales = [2**(float(s) / scales_per_octave) for s in range(scales_per_octave)]
def get(self, layer_id):
widths = []
heights = []
for a in self.aspect_ratios:
for s in self.scales:
base_anchor_size = 2**(self.min_level + layer_id) * self.anchor_scale
ar = sqrt(a)
heights.append(base_anchor_size * s / ar)
widths.append(base_anchor_size * s * ar)
return widths, heights
def createSSDGraph(modelPath, configPath, outputPath):
# Nodes that should be kept.
keepOps = ['Conv2D', 'BiasAdd', 'Add', 'AddV2', 'Relu', 'Relu6', 'Placeholder', 'FusedBatchNorm',
'DepthwiseConv2dNative', 'ConcatV2', 'Mul', 'MaxPool', 'AvgPool', 'Identity',
'Sub', 'ResizeNearestNeighbor', 'Pad', 'FusedBatchNormV3', 'Mean']
# Node with which prefixes should be removed
prefixesToRemove = ('MultipleGridAnchorGenerator/', 'Concatenate/', 'Postprocessor/', 'Preprocessor/map')
# Load a config file.
config = readTextMessage(configPath)
config = config['model'][0]['ssd'][0]
num_classes = int(config['num_classes'][0])
fixed_shape_resizer = config['image_resizer'][0]['fixed_shape_resizer'][0]
image_width = int(fixed_shape_resizer['width'][0])
image_height = int(fixed_shape_resizer['height'][0])
box_predictor = 'convolutional' if 'convolutional_box_predictor' in config['box_predictor'][0] else 'weight_shared_convolutional'
anchor_generator = config['anchor_generator'][0]
if 'ssd_anchor_generator' in anchor_generator:
ssd_anchor_generator = anchor_generator['ssd_anchor_generator'][0]
min_scale = float(ssd_anchor_generator['min_scale'][0])
max_scale = float(ssd_anchor_generator['max_scale'][0])
num_layers = int(ssd_anchor_generator['num_layers'][0])
aspect_ratios = [float(ar) for ar in ssd_anchor_generator['aspect_ratios']]
reduce_boxes_in_lowest_layer = True
if 'reduce_boxes_in_lowest_layer' in ssd_anchor_generator:
reduce_boxes_in_lowest_layer = ssd_anchor_generator['reduce_boxes_in_lowest_layer'][0] == 'true'
priors_generator = SSDAnchorGenerator(min_scale, max_scale, num_layers,
aspect_ratios, reduce_boxes_in_lowest_layer,
image_width, image_height)
print('Scale: [%f-%f]' % (min_scale, max_scale))
print('Aspect ratios: %s' % str(aspect_ratios))
print('Reduce boxes in the lowest layer: %s' % str(reduce_boxes_in_lowest_layer))
elif 'multiscale_anchor_generator' in anchor_generator:
multiscale_anchor_generator = anchor_generator['multiscale_anchor_generator'][0]
min_level = int(multiscale_anchor_generator['min_level'][0])
max_level = int(multiscale_anchor_generator['max_level'][0])
anchor_scale = float(multiscale_anchor_generator['anchor_scale'][0])
aspect_ratios = [float(ar) for ar in multiscale_anchor_generator['aspect_ratios']]
scales_per_octave = int(multiscale_anchor_generator['scales_per_octave'][0])
num_layers = max_level - min_level + 1
priors_generator = MultiscaleAnchorGenerator(min_level, aspect_ratios,
scales_per_octave, anchor_scale)
print('Levels: [%d-%d]' % (min_level, max_level))
print('Anchor scale: %f' % anchor_scale)
print('Scales per octave: %d' % scales_per_octave)
print('Aspect ratios: %s' % str(aspect_ratios))
else:
print('Unknown anchor_generator')
exit(0)
print('Number of classes: %d' % num_classes)
print('Number of layers: %d' % num_layers)
print('box predictor: %s' % box_predictor)
print('Input image size: %dx%d' % (image_width, image_height))
# Read the graph.
outNames = ['num_detections', 'detection_scores', 'detection_boxes', 'detection_classes']
writeTextGraph(modelPath, outputPath, outNames)
graph_def = parseTextGraph(outputPath)
def getUnconnectedNodes():
unconnected = []
for node in graph_def.node:
unconnected.append(node.name)
for inp in node.input:
if inp in unconnected:
unconnected.remove(inp)
return unconnected
def fuse_nodes(nodesToKeep):
# Detect unfused batch normalization nodes and fuse them.
# Add_0 <-- moving_variance, add_y
# Rsqrt <-- Add_0
# Mul_0 <-- Rsqrt, gamma
# Mul_1 <-- input, Mul_0
# Mul_2 <-- moving_mean, Mul_0
# Sub_0 <-- beta, Mul_2
# Add_1 <-- Mul_1, Sub_0
nodesMap = {node.name: node for node in graph_def.node}
subgraphBatchNorm = ['Add',
['Mul', 'input', ['Mul', ['Rsqrt', ['Add', 'moving_variance', 'add_y']], 'gamma']],
['Sub', 'beta', ['Mul', 'moving_mean', 'Mul_0']]]
subgraphBatchNormV2 = ['AddV2',
['Mul', 'input', ['Mul', ['Rsqrt', ['AddV2', 'moving_variance', 'add_y']], 'gamma']],
['Sub', 'beta', ['Mul', 'moving_mean', 'Mul_0']]]
# Detect unfused nearest neighbor resize.
subgraphResizeNN = ['Reshape',
['Mul', ['Reshape', 'input', ['Pack', 'shape_1', 'shape_2', 'shape_3', 'shape_4', 'shape_5']],
'ones'],
['Pack', ['StridedSlice', ['Shape', 'input'], 'stack', 'stack_1', 'stack_2'],
'out_height', 'out_width', 'out_channels']]
def checkSubgraph(node, targetNode, inputs, fusedNodes):
op = targetNode[0]
if node.op == op and (len(node.input) >= len(targetNode) - 1):
fusedNodes.append(node)
for i, inpOp in enumerate(targetNode[1:]):
if isinstance(inpOp, list):
if not node.input[i] in nodesMap or \
not checkSubgraph(nodesMap[node.input[i]], inpOp, inputs, fusedNodes):
return False
else:
inputs[inpOp] = node.input[i]
return True
else:
return False
nodesToRemove = []
for node in graph_def.node:
inputs = {}
fusedNodes = []
if checkSubgraph(node, subgraphBatchNorm, inputs, fusedNodes) or \
checkSubgraph(node, subgraphBatchNormV2, inputs, fusedNodes):
name = node.name
node.Clear()
node.name = name
node.op = 'FusedBatchNorm'
node.input.append(inputs['input'])
node.input.append(inputs['gamma'])
node.input.append(inputs['beta'])
node.input.append(inputs['moving_mean'])
node.input.append(inputs['moving_variance'])
node.addAttr('epsilon', 0.001)
nodesToRemove += fusedNodes[1:]
inputs = {}
fusedNodes = []
if checkSubgraph(node, subgraphResizeNN, inputs, fusedNodes):
name = node.name
node.Clear()
node.name = name
node.op = 'ResizeNearestNeighbor'
node.input.append(inputs['input'])
node.input.append(name + '/output_shape')
out_height_node = nodesMap[inputs['out_height']]
out_width_node = nodesMap[inputs['out_width']]
out_height = int(out_height_node.attr['value']['tensor'][0]['int_val'][0])
out_width = int(out_width_node.attr['value']['tensor'][0]['int_val'][0])
shapeNode = NodeDef()
shapeNode.name = name + '/output_shape'
shapeNode.op = 'Const'
shapeNode.addAttr('value', [out_height, out_width])
graph_def.node.insert(graph_def.node.index(node), shapeNode)
nodesToKeep.append(shapeNode.name)
nodesToRemove += fusedNodes[1:]
for node in nodesToRemove:
graph_def.node.remove(node)
nodesToKeep = []
fuse_nodes(nodesToKeep)
removeIdentity(graph_def)
def to_remove(name, op):
return (not name in nodesToKeep) and \
(op == 'Const' or (not op in keepOps) or name.startswith(prefixesToRemove))
removeUnusedNodesAndAttrs(to_remove, graph_def)
# Connect input node to the first layer
assert(graph_def.node[0].op == 'Placeholder')
try:
input_shape = graph_def.node[0].attr['shape']['shape'][0]['dim']
input_shape[1]['size'] = image_height
input_shape[2]['size'] = image_width
except:
print("Input shapes are undefined")
# assert(graph_def.node[1].op == 'Conv2D')
weights = graph_def.node[1].input[-1]
for i in range(len(graph_def.node[1].input)):
graph_def.node[1].input.pop()
graph_def.node[1].input.append(graph_def.node[0].name)
graph_def.node[1].input.append(weights)
# check and correct the case when preprocessing block is after input
preproc_id = "Preprocessor/"
if graph_def.node[2].name.startswith(preproc_id) and \
graph_def.node[2].input[0].startswith(preproc_id):
if not any(preproc_id in inp for inp in graph_def.node[3].input):
graph_def.node[3].input.insert(0, graph_def.node[2].name)
# Create SSD postprocessing head ###############################################
# Concatenate predictions of classes, predictions of bounding boxes and proposals.
def addConcatNode(name, inputs, axisNodeName):
concat = NodeDef()
concat.name = name
concat.op = 'ConcatV2'
for inp in inputs:
concat.input.append(inp)
concat.input.append(axisNodeName)
graph_def.node.extend([concat])
addConstNode('concat/axis_flatten', [-1], graph_def)
addConstNode('PriorBox/concat/axis', [-2], graph_def)
for label in ['ClassPredictor', 'BoxEncodingPredictor' if box_predictor is 'convolutional' else 'BoxPredictor']:
concatInputs = []
for i in range(num_layers):
# Flatten predictions
flatten = NodeDef()
if box_predictor is 'convolutional':
inpName = 'BoxPredictor_%d/%s/BiasAdd' % (i, label)
else:
if i == 0:
inpName = 'WeightSharedConvolutionalBoxPredictor/%s/BiasAdd' % label
else:
inpName = 'WeightSharedConvolutionalBoxPredictor_%d/%s/BiasAdd' % (i, label)
flatten.input.append(inpName)
flatten.name = inpName + '/Flatten'
flatten.op = 'Flatten'
concatInputs.append(flatten.name)
graph_def.node.extend([flatten])
addConcatNode('%s/concat' % label, concatInputs, 'concat/axis_flatten')
num_matched_layers = 0
for node in graph_def.node:
if re.match('BoxPredictor_\d/BoxEncodingPredictor/convolution', node.name) or \
re.match('BoxPredictor_\d/BoxEncodingPredictor/Conv2D', node.name) or \
re.match('WeightSharedConvolutionalBoxPredictor(_\d)*/BoxPredictor/Conv2D', node.name):
node.addAttr('loc_pred_transposed', True)
num_matched_layers += 1
assert(num_matched_layers == num_layers)
# Add layers that generate anchors (bounding boxes proposals).
priorBoxes = []
boxCoder = config['box_coder'][0]
fasterRcnnBoxCoder = boxCoder['faster_rcnn_box_coder'][0]
boxCoderVariance = [1.0/float(fasterRcnnBoxCoder['x_scale'][0]), 1.0/float(fasterRcnnBoxCoder['y_scale'][0]), 1.0/float(fasterRcnnBoxCoder['width_scale'][0]), 1.0/float(fasterRcnnBoxCoder['height_scale'][0])]
for i in range(num_layers):
priorBox = NodeDef()
priorBox.name = 'PriorBox_%d' % i
priorBox.op = 'PriorBox'
if box_predictor is 'convolutional':
priorBox.input.append('BoxPredictor_%d/BoxEncodingPredictor/BiasAdd' % i)
else:
if i == 0:
priorBox.input.append('WeightSharedConvolutionalBoxPredictor/BoxPredictor/Conv2D')
else:
priorBox.input.append('WeightSharedConvolutionalBoxPredictor_%d/BoxPredictor/BiasAdd' % i)
priorBox.input.append(graph_def.node[0].name) # image_tensor
priorBox.addAttr('flip', False)
priorBox.addAttr('clip', False)
widths, heights = priors_generator.get(i)
priorBox.addAttr('width', widths)
priorBox.addAttr('height', heights)
priorBox.addAttr('variance', boxCoderVariance)
graph_def.node.extend([priorBox])
priorBoxes.append(priorBox.name)
# Compare this layer's output with Postprocessor/Reshape
addConcatNode('PriorBox/concat', priorBoxes, 'concat/axis_flatten')
# Sigmoid for classes predictions and DetectionOutput layer
addReshape('ClassPredictor/concat', 'ClassPredictor/concat3d', [0, -1, num_classes + 1], graph_def)
sigmoid = NodeDef()
sigmoid.name = 'ClassPredictor/concat/sigmoid'
sigmoid.op = 'Sigmoid'
sigmoid.input.append('ClassPredictor/concat3d')
graph_def.node.extend([sigmoid])
addFlatten(sigmoid.name, sigmoid.name + '/Flatten', graph_def)
detectionOut = NodeDef()
detectionOut.name = 'detection_out'
detectionOut.op = 'DetectionOutput'
if box_predictor == 'convolutional':
detectionOut.input.append('BoxEncodingPredictor/concat')
else:
detectionOut.input.append('BoxPredictor/concat')
detectionOut.input.append(sigmoid.name + '/Flatten')
detectionOut.input.append('PriorBox/concat')
detectionOut.addAttr('num_classes', num_classes + 1)
detectionOut.addAttr('share_location', True)
detectionOut.addAttr('background_label_id', 0)
postProcessing = config['post_processing'][0]
batchNMS = postProcessing['batch_non_max_suppression'][0]
if 'iou_threshold' in batchNMS:
detectionOut.addAttr('nms_threshold', float(batchNMS['iou_threshold'][0]))
else:
detectionOut.addAttr('nms_threshold', 0.6)
if 'score_threshold' in batchNMS:
detectionOut.addAttr('confidence_threshold', float(batchNMS['score_threshold'][0]))
else:
detectionOut.addAttr('confidence_threshold', 0.01)
if 'max_detections_per_class' in batchNMS:
detectionOut.addAttr('top_k', int(batchNMS['max_detections_per_class'][0]))
else:
detectionOut.addAttr('top_k', 100)
if 'max_total_detections' in batchNMS:
detectionOut.addAttr('keep_top_k', int(batchNMS['max_total_detections'][0]))
else:
detectionOut.addAttr('keep_top_k', 100)
detectionOut.addAttr('code_type', "CENTER_SIZE")
graph_def.node.extend([detectionOut])
while True:
unconnectedNodes = getUnconnectedNodes()
unconnectedNodes.remove(detectionOut.name)
if not unconnectedNodes:
break
for name in unconnectedNodes:
for i in range(len(graph_def.node)):
if graph_def.node[i].name == name:
del graph_def.node[i]
break
# Save as text.
graph_def.save(outputPath)
if __name__ == "__main__":
parser = argparse.ArgumentParser(description='Run this script to get a text graph of '
'SSD model from TensorFlow Object Detection API. '
'Then pass it with .pb file to cv::dnn::readNetFromTensorflow function.')
parser.add_argument('--input', required=True, help='Path to frozen TensorFlow graph.')
parser.add_argument('--output', required=True, help='Path to output text graph.')
parser.add_argument('--config', required=True, help='Path to a *.config file is used for training.')
args = parser.parse_args()
createSSDGraph(args.input, args.config, args.output)