What is the function of the image_gt_data_layer ？

[skyforwork]

@zhaoweicai What is the function of the image_gt_data_layer ？And what does the outputs in this layer mean ？

layer {
top: "data"
top: "label_1_5x5"
top: "label_1_7x7"
top: "label_2_5x5"
top: "label_2_7x7"
top: "label_3_5x5"
top: "label_3_7x7"
top: "label_4_5x5"
name: "data"
type: "ImageGtData"
include {
phase: TRAIN
}
transform_param {
mirror: true
mean_value: 104
mean_value: 117
mean_value: 123
}
image_gt_data_param {
source: "../../../data/kitti/window_files/mscnn_window_file_kitti_vehicle_train.txt"
batch_size: 4
coord_num: 4
resize_width: 1280
resize_height: 384
crop_width: 512
crop_height: 384
min_gt_height: 25
downsample_rate: 8
downsample_rate: 8
downsample_rate: 16
downsample_rate: 16
downsample_rate: 32
downsample_rate: 32
downsample_rate: 64
field_w: 40
field_w: 56
field_w: 80
field_w: 112
field_w: 160
field_w: 224
field_w: 320
field_h: 40
field_h: 56
field_h: 80
field_h: 112
field_h: 160
field_h: 224
field_h: 320
fg_threshold: 0.5
do_multiple_scale: true
min_scale: 40
max_scale: 320
shuffle: true
}
}

[zhaoweicai]

This layer pre-processes the input images, and outputs data and label blobs for later layers. The output image data is at a single scale, and the output label data is at multiple scales for multi-scale proposal generation training.