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Motion R-CNN

This repository contains the TensorFlow prototype implementation of my bachelor thesis Motion R-CNN: Instance-level 3D Motion Estimation with Region-based CNNs.

In addition to the functionality provided by the TensorFlow Object Detection API (at the time of writing), the code supports:

• prediction of instance masks for detected objects
• Feature Pyramid Networks
• prediction of inter-frame 3D camera ego-motion (translation and rotation) given a second image temporally consecutive to the first image
• prediction of 3D motions (translation and rotation) between the two frames for all objects detected in the first frame

Note that the code only supports training on the Virtual KITTI dataset, but it is easy to adapt it to other datasets. Motion prediction and frame pair input is fully optional and the code can be used as a Mask R-CNN implementation with single image input. Support for cityscapes is implemented, but using the records created with create_citiscapes_tf_record.py may require adapting the data_decoder or the record writing as the record interface changed.

License

Motion R-CNN is released under the MIT License (refer to the LICENSE file for details).

Usage

Requirements

• tensorflow (>= 1.3.0) with GPU support.
• sudo apt-get install protobuf-compiler
• pip install opencv-python pandas pillow lxml matplotlib

Setup

• from the project root directory, run export PYTHONPATH=$PYTHONPATH:`pwd`:`pwd`/slim
• download and extract the pre-trained ResNet-50 model to object_detection/data
• download all of the Virtual KITTI ground truth and extract the folders into a directory named vkitti.
• cd to the project root directory
• run protoc object_detection/protos/*.proto --python_out=.
• run python create_vkitti_tf_record.py --data_dir=<data_parent_dir> --output_dir=data/records --set val
• run python create_vkitti_tf_record.py --data_dir=<data_parent_dir> --output_dir=data/records --set train

Note that <data_parent_dir> is the directory containing the vkitti directory.

Training & evaluating

Use

• python train.py --logtostderr --pipeline_config_path=data/configs/motion_rcnn_vkitti_cam.config --train_dir=output/train/motion_rcnn_vkitti_cam --gpu 0
• python eval.py --logtostderr --pipeline_config_path=data/configs/motion_rcnn_vkitti_cam.config --checkpoint_dir=output/train/motion_rcnn_vkitti_cam --eval_dir=output/eval/motion_rcnn_vkitti_cam

to train and evaluate a model with camera and instance motion prediction. You can adapt the configurations found in data/configs/. For a description of the configuration parameters, see object_detection/protos.

Navigating the code

The following files were added or modified from the original Object Detection API code

• motion_util.py: losses for training the motion estimation and post-processing utilities
• np_motion_util.py: composition of optical flow using motion predictions and performance evaluation utilities
• create_vkitti_tf_record.py: process virtual kitti dataset
• create_cityscapes_tf_record.py: process cityscapes dataset
• faster_rcnn_meta_arch.py: adapted to support instance mask, instance motion, and camera motion training.
• target_assigner.py: updated to support mask and motion target assignment
• box_predictor.py: updated to support FPN as well as mask and motion prediction
• post_processing.py: updated to pass through instance motions
• faster_rcnn_resnet_v1_fpn_feature_extractor.py: FPN feature extractor
• faster_rcnn_resnet_v1_feature_extractor.py: added support for camera branch

Additionally, some proto params and builders were modified, and extensions were made to eval_util.py, eval.py, evaluator.py, train.py, trainer.py.

The following tests were added or modified:

• object_detection.core.box_predictor_test
• object_detection.core.post_processing_test
• object_detection.models.faster_rcnn_resnet_v1_feature_extractor_test
• object_detection.models.faster_rcnn_resnet_v1_fpn_feature_extractor_test
• object_detection.anchor_generators.multiple_grid_anchor_generator_test
• object_detection.meta_architectures.faster_rcnn_meta_arch_test

Acknowledgments

This repository is based on the TensorFlow Object Detection API.