def create_faster_rcnn_eval_model(model, image_input, dims_input, cfg, rpn_model=None):
    print("creating eval model")
    last_conv_node_name = cfg["MODEL"].LAST_CONV_NODE_NAME
    conv_layers = clone_model(model, [cfg["MODEL"].FEATURE_NODE_NAME], [last_conv_node_name], CloneMethod.freeze)
    conv_out = conv_layers(image_input)

    model_with_rpn = model if rpn_model is None else rpn_model
    rpn = clone_model(model_with_rpn, [last_conv_node_name], ["rpn_cls_prob_reshape", "rpn_bbox_pred"], CloneMethod.freeze)
    rpn_out = rpn(conv_out)
    # we need to add the proposal layer anew to account for changing configs when buffering proposals in 4-stage training
    rpn_rois = create_proposal_layer(rpn_out.outputs[0], rpn_out.outputs[1], dims_input, cfg)

    roi_fc_layers = clone_model(model, [last_conv_node_name, "rpn_target_rois"], ["cls_score", "bbox_regr"], CloneMethod.freeze)
    pred_net = roi_fc_layers(conv_out, rpn_rois)
    cls_score = pred_net.outputs[0]
    bbox_regr = pred_net.outputs[1]

    if cfg.BBOX_NORMALIZE_TARGETS:
        num_boxes = int(bbox_regr.shape[1] / 4)
        bbox_normalize_means = np.array(cfg.BBOX_NORMALIZE_MEANS * num_boxes)
        bbox_normalize_stds = np.array(cfg.BBOX_NORMALIZE_STDS * num_boxes)
        bbox_regr = plus(element_times(bbox_regr, bbox_normalize_stds), bbox_normalize_means, name='bbox_regr')

    cls_pred = softmax(cls_score, axis=1, name='cls_pred')
    eval_model = combine([cls_pred, rpn_rois, bbox_regr])

    return eval_model
Exemple #2
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def create_faster_rcnn_eval_model(model, image_input, dims_input, cfg, rpn_model=None):
    print("creating eval model")
    last_conv_node_name = cfg["MODEL"].LAST_CONV_NODE_NAME
    conv_layers = clone_model(model, [cfg["MODEL"].FEATURE_NODE_NAME], [last_conv_node_name], CloneMethod.freeze)
    conv_out = conv_layers(image_input)

    model_with_rpn = model if rpn_model is None else rpn_model
    rpn = clone_model(model_with_rpn, [last_conv_node_name], ["rpn_cls_prob_reshape", "rpn_bbox_pred"], CloneMethod.freeze)
    rpn_out = rpn(conv_out)
    # we need to add the proposal layer anew to account for changing configs when buffering proposals in 4-stage training
    rpn_rois = create_proposal_layer(rpn_out.outputs[0], rpn_out.outputs[1], dims_input, cfg)

    roi_fc_layers = clone_model(model, [last_conv_node_name, "rpn_target_rois"], ["cls_score", "bbox_regr"], CloneMethod.freeze)
    pred_net = roi_fc_layers(conv_out, rpn_rois)
    cls_score = pred_net.outputs[0]
    bbox_regr = pred_net.outputs[1]

    if cfg.BBOX_NORMALIZE_TARGETS:
        num_boxes = int(bbox_regr.shape[1] / 4)
        bbox_normalize_means = np.array(cfg.BBOX_NORMALIZE_MEANS * num_boxes)
        bbox_normalize_stds = np.array(cfg.BBOX_NORMALIZE_STDS * num_boxes)
        bbox_regr = plus(element_times(bbox_regr, bbox_normalize_stds), bbox_normalize_means, name='bbox_regr')

    cls_pred = softmax(cls_score, axis=1, name='cls_pred')
    eval_model = combine([cls_pred, rpn_rois, bbox_regr])

    return eval_model
def create_faster_rcnn_model(features, scaled_gt_boxes, dims_input, cfg):
    # Load the pre-trained classification net and clone layers
    base_model = load_model(cfg['BASE_MODEL_PATH'])
    conv_layers = clone_conv_layers(base_model, cfg)
    fc_layers = clone_model(base_model, [cfg["MODEL"].POOL_NODE_NAME],
                            [cfg["MODEL"].LAST_HIDDEN_NODE_NAME],
                            clone_method=CloneMethod.clone)

    # Normalization and conv layers
    feat_norm = features - Constant([[[v]]
                                     for v in cfg["MODEL"].IMG_PAD_COLOR])
    conv_out = conv_layers(feat_norm)

    # RPN and prediction targets
    rpn_rois, rpn_losses = create_rpn(conv_out, scaled_gt_boxes, dims_input,
                                      cfg)
    rois, label_targets, bbox_targets, bbox_inside_weights = \
        create_proposal_target_layer(rpn_rois, scaled_gt_boxes, cfg)

    # Fast RCNN and losses
    cls_score, bbox_pred = create_fast_rcnn_predictor(conv_out, rois,
                                                      fc_layers, cfg)
    detection_losses = create_detection_losses(cls_score, label_targets,
                                               bbox_pred, rois, bbox_targets,
                                               bbox_inside_weights, cfg)
    loss = rpn_losses + detection_losses
    pred_error = classification_error(cls_score, label_targets, axis=1)

    return loss, pred_error
Exemple #4
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def create_faster_rcnn_model(features, scaled_gt_boxes, dims_input, cfg):
    # Load the pre-trained classification net and clone layers
    base_model = load_model(cfg['BASE_MODEL_PATH'])
    conv_layers = clone_conv_layers(base_model, cfg)
    fc_layers = clone_model(base_model, [cfg["MODEL"].POOL_NODE_NAME], [cfg["MODEL"].LAST_HIDDEN_NODE_NAME], clone_method=CloneMethod.clone)

    # Normalization and conv layers
    feat_norm = features - Constant([[[v]] for v in cfg["MODEL"].IMG_PAD_COLOR])
    conv_out = conv_layers(feat_norm)

    # RPN and prediction targets
    rpn_rois, rpn_losses = create_rpn(conv_out, scaled_gt_boxes, dims_input, cfg)
    rois, label_targets, bbox_targets, bbox_inside_weights = \
        create_proposal_target_layer(rpn_rois, scaled_gt_boxes, cfg)

    # Fast RCNN and losses
    cls_score, bbox_pred = create_fast_rcnn_predictor(conv_out, rois, fc_layers, cfg)
    detection_losses = create_detection_losses(cls_score, label_targets, bbox_pred, rois, bbox_targets, bbox_inside_weights, cfg)
    loss = rpn_losses + detection_losses
    pred_error = classification_error(cls_score, label_targets, axis=1)

    return loss, pred_error
def train_faster_rcnn_alternating(cfg):
    '''
        4-Step Alternating Training scheme from the Faster R-CNN paper:
        
        # Create initial network, only rpn, without detection network
            # --> train only the rpn (and conv3_1 and up for VGG16)
        # buffer region proposals from rpn
        # Create full network, initialize conv layers with imagenet, use buffered proposals
            # --> train only detection network (and conv3_1 and up for VGG16)
        # Keep conv weights from detection network and fix them
            # --> train only rpn
        # buffer region proposals from rpn
        # Keep conv and rpn weights from step 3 and fix them
            # --> train only detection network
    '''

    # setting pre- and post-nms top N to training values since buffered proposals are used for further training
    test_pre = cfg["TEST"].RPN_PRE_NMS_TOP_N
    test_post = cfg["TEST"].RPN_POST_NMS_TOP_N
    cfg["TEST"].RPN_PRE_NMS_TOP_N = cfg["TRAIN"].RPN_PRE_NMS_TOP_N
    cfg["TEST"].RPN_POST_NMS_TOP_N = cfg["TRAIN"].RPN_POST_NMS_TOP_N

    # Learning parameters
    rpn_lr_factor = cfg["MODEL"].RPN_LR_FACTOR
    rpn_lr_per_sample_scaled = [x * rpn_lr_factor for x in cfg["CNTK"].RPN_LR_PER_SAMPLE]
    frcn_lr_factor = cfg["MODEL"].FRCN_LR_FACTOR
    frcn_lr_per_sample_scaled = [x * frcn_lr_factor for x in cfg["CNTK"].FRCN_LR_PER_SAMPLE]

    l2_reg_weight = cfg["CNTK"].L2_REG_WEIGHT
    mm_schedule = momentum_schedule(cfg["CNTK"].MOMENTUM_PER_MB)
    rpn_epochs = cfg["CNTK"].RPN_EPOCHS
    frcn_epochs = cfg["CNTK"].FRCN_EPOCHS

    feature_node_name = cfg["MODEL"].FEATURE_NODE_NAME
    last_conv_node_name = cfg["MODEL"].LAST_CONV_NODE_NAME
    print("Using base model:   {}".format(cfg["MODEL"].BASE_MODEL))
    print("rpn_lr_per_sample:  {}".format(rpn_lr_per_sample_scaled))
    print("frcn_lr_per_sample: {}".format(frcn_lr_per_sample_scaled))

    debug_output=cfg["CNTK"].DEBUG_OUTPUT
    if debug_output:
        print("Storing graphs and models to %s." % cfg.OUTPUT_PATH)

    # Input variables denoting features, labeled ground truth rois (as 5-tuples per roi) and image dimensions
    image_input = input_variable(shape=(cfg.NUM_CHANNELS, cfg.IMAGE_HEIGHT, cfg.IMAGE_WIDTH),
                                 dynamic_axes=[Axis.default_batch_axis()],
                                 name=feature_node_name)
    feat_norm = image_input - Constant([[[v]] for v in cfg["MODEL"].IMG_PAD_COLOR])
    roi_input = input_variable((cfg.INPUT_ROIS_PER_IMAGE, 5), dynamic_axes=[Axis.default_batch_axis()])
    scaled_gt_boxes = alias(roi_input, name='roi_input')
    dims_input = input_variable((6), dynamic_axes=[Axis.default_batch_axis()])
    dims_node = alias(dims_input, name='dims_input')
    rpn_rois_input = input_variable((cfg["TRAIN"].RPN_POST_NMS_TOP_N, 4), dynamic_axes=[Axis.default_batch_axis()])
    rpn_rois_buf = alias(rpn_rois_input, name='rpn_rois')

    # base image classification model (e.g. VGG16 or AlexNet)
    base_model = load_model(cfg['BASE_MODEL_PATH'])

    print("stage 1a - rpn")
    if True:
        # Create initial network, only rpn, without detection network
            #       initial weights     train?
            # conv: base_model          only conv3_1 and up
            # rpn:  init new            yes
            # frcn: -                   -

        # conv layers
        conv_layers = clone_conv_layers(base_model, cfg)
        conv_out = conv_layers(feat_norm)

        # RPN and losses
        rpn_rois, rpn_losses = create_rpn(conv_out, scaled_gt_boxes, dims_node, cfg)
        stage1_rpn_network = combine([rpn_rois, rpn_losses])

        # train
        if debug_output: plot(stage1_rpn_network, os.path.join(cfg.OUTPUT_PATH, "graph_frcn_train_stage1a_rpn." + cfg["CNTK"].GRAPH_TYPE))
        train_model(image_input, roi_input, dims_input, rpn_losses, rpn_losses,
                    rpn_lr_per_sample_scaled, mm_schedule, l2_reg_weight, rpn_epochs, cfg)

    print("stage 1a - buffering rpn proposals")
    buffered_proposals_s1 = compute_rpn_proposals(stage1_rpn_network, image_input, roi_input, dims_input, cfg)

    print("stage 1b - frcn")
    if True:
        # Create full network, initialize conv layers with imagenet, fix rpn weights
            #       initial weights     train?
            # conv: base_model          only conv3_1 and up
            # rpn:  stage1a rpn model   no --> use buffered proposals
            # frcn: base_model + new    yes

        # conv_layers
        conv_layers = clone_conv_layers(base_model, cfg)
        conv_out = conv_layers(feat_norm)

        # use buffered proposals in target layer
        rois, label_targets, bbox_targets, bbox_inside_weights = \
            create_proposal_target_layer(rpn_rois_buf, scaled_gt_boxes, cfg)

        # Fast RCNN and losses
        fc_layers = clone_model(base_model, [cfg["MODEL"].POOL_NODE_NAME], [cfg["MODEL"].LAST_HIDDEN_NODE_NAME], CloneMethod.clone)
        cls_score, bbox_pred = create_fast_rcnn_predictor(conv_out, rois, fc_layers, cfg)
        detection_losses = create_detection_losses(cls_score, label_targets, bbox_pred, rois, bbox_targets, bbox_inside_weights, cfg)
        pred_error = classification_error(cls_score, label_targets, axis=1, name="pred_error")
        stage1_frcn_network = combine([rois, cls_score, bbox_pred, detection_losses, pred_error])

        # train
        if debug_output: plot(stage1_frcn_network, os.path.join(cfg.OUTPUT_PATH, "graph_frcn_train_stage1b_frcn." + cfg["CNTK"].GRAPH_TYPE))
        train_model(image_input, roi_input, dims_input, detection_losses, pred_error,
                    frcn_lr_per_sample_scaled, mm_schedule, l2_reg_weight, frcn_epochs, cfg,
                    rpn_rois_input=rpn_rois_input, buffered_rpn_proposals=buffered_proposals_s1)
        buffered_proposals_s1 = None

    print("stage 2a - rpn")
    if True:
        # Keep conv weights from detection network and fix them
            #       initial weights     train?
            # conv: stage1b frcn model  no
            # rpn:  stage1a rpn model   yes
            # frcn: -                   -

        # conv_layers
        conv_layers = clone_model(stage1_frcn_network, [feature_node_name], [last_conv_node_name], CloneMethod.freeze)
        conv_out = conv_layers(image_input)

        # RPN and losses
        rpn = clone_model(stage1_rpn_network, [last_conv_node_name, "roi_input", "dims_input"], ["rpn_rois", "rpn_losses"], CloneMethod.clone)
        rpn_net = rpn(conv_out, dims_node, scaled_gt_boxes)
        rpn_rois = rpn_net.outputs[0]
        rpn_losses = rpn_net.outputs[1]
        stage2_rpn_network = combine([rpn_rois, rpn_losses])

        # train
        if debug_output: plot(stage2_rpn_network, os.path.join(cfg.OUTPUT_PATH, "graph_frcn_train_stage2a_rpn." + cfg["CNTK"].GRAPH_TYPE))
        train_model(image_input, roi_input, dims_input, rpn_losses, rpn_losses,
                    rpn_lr_per_sample_scaled, mm_schedule, l2_reg_weight, rpn_epochs, cfg)

    print("stage 2a - buffering rpn proposals")
    buffered_proposals_s2 = compute_rpn_proposals(stage2_rpn_network, image_input, roi_input, dims_input, cfg)

    print("stage 2b - frcn")
    if True:
        # Keep conv and rpn weights from step 3 and fix them
            #       initial weights     train?
            # conv: stage2a rpn model   no
            # rpn:  stage2a rpn model   no --> use buffered proposals
            # frcn: stage1b frcn model  yes                   -

        # conv_layers
        conv_layers = clone_model(stage2_rpn_network, [feature_node_name], [last_conv_node_name], CloneMethod.freeze)
        conv_out = conv_layers(image_input)

        # Fast RCNN and losses
        frcn = clone_model(stage1_frcn_network, [last_conv_node_name, "rpn_rois", "roi_input"],
                           ["cls_score", "bbox_regr", "rpn_target_rois", "detection_losses", "pred_error"], CloneMethod.clone)
        stage2_frcn_network = frcn(conv_out, rpn_rois_buf, scaled_gt_boxes)
        detection_losses = stage2_frcn_network.outputs[3]
        pred_error = stage2_frcn_network.outputs[4]

        # train
        if debug_output: plot(stage2_frcn_network, os.path.join(cfg.OUTPUT_PATH, "graph_frcn_train_stage2b_frcn." + cfg["CNTK"].GRAPH_TYPE))
        train_model(image_input, roi_input, dims_input, detection_losses, pred_error,
                    frcn_lr_per_sample_scaled, mm_schedule, l2_reg_weight, frcn_epochs, cfg,
                    rpn_rois_input=rpn_rois_input, buffered_rpn_proposals=buffered_proposals_s2)
        buffered_proposals_s2 = None

    # resetting config values to original test values
    cfg["TEST"].RPN_PRE_NMS_TOP_N = test_pre
    cfg["TEST"].RPN_POST_NMS_TOP_N = test_post

    return create_faster_rcnn_eval_model(stage2_frcn_network, image_input, dims_input, cfg, rpn_model=stage2_rpn_network)
Exemple #6
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def train_faster_rcnn_alternating(cfg):
    '''
        4-Step Alternating Training scheme from the Faster R-CNN paper:
        
        # Create initial network, only rpn, without detection network
            # --> train only the rpn (and conv3_1 and up for VGG16)
        # buffer region proposals from rpn
        # Create full network, initialize conv layers with imagenet, use buffered proposals
            # --> train only detection network (and conv3_1 and up for VGG16)
        # Keep conv weights from detection network and fix them
            # --> train only rpn
        # buffer region proposals from rpn
        # Keep conv and rpn weights from step 3 and fix them
            # --> train only detection network
    '''

    # setting pre- and post-nms top N to training values since buffered proposals are used for further training
    test_pre = cfg["TEST"].RPN_PRE_NMS_TOP_N
    test_post = cfg["TEST"].RPN_POST_NMS_TOP_N
    cfg["TEST"].RPN_PRE_NMS_TOP_N = cfg["TRAIN"].RPN_PRE_NMS_TOP_N
    cfg["TEST"].RPN_POST_NMS_TOP_N = cfg["TRAIN"].RPN_POST_NMS_TOP_N

    # Learning parameters
    rpn_lr_factor = cfg["MODEL"].RPN_LR_FACTOR
    rpn_lr_per_sample_scaled = [x * rpn_lr_factor for x in cfg["CNTK"].RPN_LR_PER_SAMPLE]
    frcn_lr_factor = cfg["MODEL"].FRCN_LR_FACTOR
    frcn_lr_per_sample_scaled = [x * frcn_lr_factor for x in cfg["CNTK"].FRCN_LR_PER_SAMPLE]

    l2_reg_weight = cfg["CNTK"].L2_REG_WEIGHT
    mm_schedule = momentum_schedule(cfg["CNTK"].MOMENTUM_PER_MB)
    rpn_epochs = cfg["CNTK"].RPN_EPOCHS
    frcn_epochs = cfg["CNTK"].FRCN_EPOCHS

    feature_node_name = cfg["MODEL"].FEATURE_NODE_NAME
    last_conv_node_name = cfg["MODEL"].LAST_CONV_NODE_NAME
    print("Using base model:   {}".format(cfg["MODEL"].BASE_MODEL))
    print("rpn_lr_per_sample:  {}".format(rpn_lr_per_sample_scaled))
    print("frcn_lr_per_sample: {}".format(frcn_lr_per_sample_scaled))

    debug_output=cfg["CNTK"].DEBUG_OUTPUT
    if debug_output:
        print("Storing graphs and models to %s." % cfg.OUTPUT_PATH)

    # Input variables denoting features, labeled ground truth rois (as 5-tuples per roi) and image dimensions
    image_input = input_variable(shape=(cfg.NUM_CHANNELS, cfg.IMAGE_HEIGHT, cfg.IMAGE_WIDTH),
                                 dynamic_axes=[Axis.default_batch_axis()],
                                 name=feature_node_name)
    feat_norm = image_input - Constant([[[v]] for v in cfg["MODEL"].IMG_PAD_COLOR])
    roi_input = input_variable((cfg.INPUT_ROIS_PER_IMAGE, 5), dynamic_axes=[Axis.default_batch_axis()])
    scaled_gt_boxes = alias(roi_input, name='roi_input')
    dims_input = input_variable((6), dynamic_axes=[Axis.default_batch_axis()])
    dims_node = alias(dims_input, name='dims_input')
    rpn_rois_input = input_variable((cfg["TRAIN"].RPN_POST_NMS_TOP_N, 4), dynamic_axes=[Axis.default_batch_axis()])
    rpn_rois_buf = alias(rpn_rois_input, name='rpn_rois')

    # base image classification model (e.g. VGG16 or AlexNet)
    base_model = load_model(cfg['BASE_MODEL_PATH'])

    print("stage 1a - rpn")
    if True:
        # Create initial network, only rpn, without detection network
            #       initial weights     train?
            # conv: base_model          only conv3_1 and up
            # rpn:  init new            yes
            # frcn: -                   -

        # conv layers
        conv_layers = clone_conv_layers(base_model, cfg)
        conv_out = conv_layers(feat_norm)

        # RPN and losses
        rpn_rois, rpn_losses = create_rpn(conv_out, scaled_gt_boxes, dims_node, cfg)
        stage1_rpn_network = combine([rpn_rois, rpn_losses])

        # train
        if debug_output: plot(stage1_rpn_network, os.path.join(cfg.OUTPUT_PATH, "graph_frcn_train_stage1a_rpn." + cfg["CNTK"].GRAPH_TYPE))
        train_model(image_input, roi_input, dims_input, rpn_losses, rpn_losses,
                    rpn_lr_per_sample_scaled, mm_schedule, l2_reg_weight, rpn_epochs, cfg)

    print("stage 1a - buffering rpn proposals")
    buffered_proposals_s1 = compute_rpn_proposals(stage1_rpn_network, image_input, roi_input, dims_input, cfg)

    print("stage 1b - frcn")
    if True:
        # Create full network, initialize conv layers with imagenet, fix rpn weights
            #       initial weights     train?
            # conv: base_model          only conv3_1 and up
            # rpn:  stage1a rpn model   no --> use buffered proposals
            # frcn: base_model + new    yes

        # conv_layers
        conv_layers = clone_conv_layers(base_model, cfg)
        conv_out = conv_layers(feat_norm)

        # use buffered proposals in target layer
        rois, label_targets, bbox_targets, bbox_inside_weights = \
            create_proposal_target_layer(rpn_rois_buf, scaled_gt_boxes, cfg)

        # Fast RCNN and losses
        fc_layers = clone_model(base_model, [cfg["MODEL"].POOL_NODE_NAME], [cfg["MODEL"].LAST_HIDDEN_NODE_NAME], CloneMethod.clone)
        cls_score, bbox_pred = create_fast_rcnn_predictor(conv_out, rois, fc_layers, cfg)
        detection_losses = create_detection_losses(cls_score, label_targets, bbox_pred, rois, bbox_targets, bbox_inside_weights, cfg)
        pred_error = classification_error(cls_score, label_targets, axis=1, name="pred_error")
        stage1_frcn_network = combine([rois, cls_score, bbox_pred, detection_losses, pred_error])

        # train
        if debug_output: plot(stage1_frcn_network, os.path.join(cfg.OUTPUT_PATH, "graph_frcn_train_stage1b_frcn." + cfg["CNTK"].GRAPH_TYPE))
        train_model(image_input, roi_input, dims_input, detection_losses, pred_error,
                    frcn_lr_per_sample_scaled, mm_schedule, l2_reg_weight, frcn_epochs, cfg,
                    rpn_rois_input=rpn_rois_input, buffered_rpn_proposals=buffered_proposals_s1)
        buffered_proposals_s1 = None

    print("stage 2a - rpn")
    if True:
        # Keep conv weights from detection network and fix them
            #       initial weights     train?
            # conv: stage1b frcn model  no
            # rpn:  stage1a rpn model   yes
            # frcn: -                   -

        # conv_layers
        conv_layers = clone_model(stage1_frcn_network, [feature_node_name], [last_conv_node_name], CloneMethod.freeze)
        conv_out = conv_layers(image_input)

        # RPN and losses
        rpn = clone_model(stage1_rpn_network, [last_conv_node_name, "roi_input", "dims_input"], ["rpn_rois", "rpn_losses"], CloneMethod.clone)
        rpn_net = rpn(conv_out, dims_node, scaled_gt_boxes)
        rpn_rois = rpn_net.outputs[0]
        rpn_losses = rpn_net.outputs[1]
        stage2_rpn_network = combine([rpn_rois, rpn_losses])

        # train
        if debug_output: plot(stage2_rpn_network, os.path.join(cfg.OUTPUT_PATH, "graph_frcn_train_stage2a_rpn." + cfg["CNTK"].GRAPH_TYPE))
        train_model(image_input, roi_input, dims_input, rpn_losses, rpn_losses,
                    rpn_lr_per_sample_scaled, mm_schedule, l2_reg_weight, rpn_epochs, cfg)

    print("stage 2a - buffering rpn proposals")
    buffered_proposals_s2 = compute_rpn_proposals(stage2_rpn_network, image_input, roi_input, dims_input, cfg)

    print("stage 2b - frcn")
    if True:
        # Keep conv and rpn weights from step 3 and fix them
            #       initial weights     train?
            # conv: stage2a rpn model   no
            # rpn:  stage2a rpn model   no --> use buffered proposals
            # frcn: stage1b frcn model  yes                   -

        # conv_layers
        conv_layers = clone_model(stage2_rpn_network, [feature_node_name], [last_conv_node_name], CloneMethod.freeze)
        conv_out = conv_layers(image_input)

        # Fast RCNN and losses
        frcn = clone_model(stage1_frcn_network, [last_conv_node_name, "rpn_rois", "roi_input"],
                           ["cls_score", "bbox_regr", "rpn_target_rois", "detection_losses", "pred_error"], CloneMethod.clone)
        stage2_frcn_network = frcn(conv_out, rpn_rois_buf, scaled_gt_boxes)
        detection_losses = stage2_frcn_network.outputs[3]
        pred_error = stage2_frcn_network.outputs[4]

        # train
        if debug_output: plot(stage2_frcn_network, os.path.join(cfg.OUTPUT_PATH, "graph_frcn_train_stage2b_frcn." + cfg["CNTK"].GRAPH_TYPE))
        train_model(image_input, roi_input, dims_input, detection_losses, pred_error,
                    frcn_lr_per_sample_scaled, mm_schedule, l2_reg_weight, frcn_epochs, cfg,
                    rpn_rois_input=rpn_rois_input, buffered_rpn_proposals=buffered_proposals_s2)
        buffered_proposals_s2 = None

    # resetting config values to original test values
    cfg["TEST"].RPN_PRE_NMS_TOP_N = test_pre
    cfg["TEST"].RPN_POST_NMS_TOP_N = test_post

    return create_faster_rcnn_eval_model(stage2_frcn_network, image_input, dims_input, cfg, rpn_model=stage2_rpn_network)