Geometry-Based Region Proposals for Accelerated Image-Based Detection of 3D Objects

Geom R-CNN is an efficient framework for 3D object detection in Robotics applications. It is specifically designed for detecting objects in table-top scenes (or similar environments with objects sitting on a dominant plane). The output of the system is a class label and 3D position for each object in the scene.

Geom R-CNN

• capitalizes on known geometric relationships to develop region proposals and localize each object
• uses a CNN for object recognition
• can be used to produce novel datasets, large enough for training deep neural net models
• runs at an average of 12 hz on a Core i7 laptop
• released as ROS package

An up-to-date version of this code will also be made available through GitHub (https://github.com/asbroad/geom_rcnn)

Installation

1. Create a ROS workspace

  mkdir -p ~/geom_rcnn_ws/src
  cd ~/geom_rcnn_ws/src
  catkin_init_workspace

2. Clone the Geom R-CNN repository in your ROS workspace

  git clone https://github.com/asbroad/geom_rcnn.git

3. From the base directory of the workspace, build the code

  cd ~/geom_rcnn_ws
  catkin_make

Requirements

Software

1. ROS (Tested with ROS Indigo and Ubuntu 14.04)
2. Keras
3. TensorFlow
4. OpenCV
5. PCL 1.2 or greater

Additional requirements for training new CNNs (Neither is strictly necessary. sklearn is used to create a training and testing split for the model development. matplotlib is used to plot results of model training).

1. sklearn
2. matplotlib

Hardware

1. If you want to work with the larger models described in the paper you will likely need a GPU. If you choose to use the small network described in the paper (and provided in code in this ), a low-tier GPU is fine (e.g. nVidia GeForce 860M). For training larger networks (e.g. VGG_16, GoogLeNet, etc...) a better GPU (e.g. TitanX) will be necessary. All networks described can run on the low-tier GPU.

Running the System

Object Detection Pipeline: To run the object detection pipeline, open a terminal and run

  roslaunch geom_rcnn full_pipeline.launch

Important parameters that can be set the 'full_pipeline.launch' file

• run_recognition
  • false (default): run full system without object recognition (you will still get object positions in 3D and bounding boxes displayed in the 2D image)
  • true: run full system with object recognition (you will need to have trained a recognition model)
• xmin, xmax, ymin, ymax, zmin, zmax : parameters for point cloud passthrough filters.
• the following are necssary for object recognition
  • model_file : the location of the stored model architecture file
  • category_file : the location of the stored object category dictionary
  • weights_file : the location of the stored model weights file

Training a new CNN model: To train a new CNN model for use in the Object Detection pipeline, open a terminal and run

  roslaunch geom_rcnn train_cnn.launch

Important parameters that can be set the 'train_cnn.launch' file

• data_dir : the location of the base directory of the training data. The structure of the dataset expected by the code is as follows. Within the base directory, each object class is broken out into its own subdirectory (the name of the subdirectory will be the class name). For example, for an apple class, there will be an 'apple' subdirectory within the data_dir, which itself contains all examples of that class (in .jpg format). this is the structure that will be automatically created if using this system to create a new dataset.
• model_file : the location where the chosen model architecture will be stored
• category_file : the location where the object category dictionary will be stored
• weights_file : the location where the learned model weights will be stored
• history_file : the location where the training history information will be stored
• train_test_split_percentage : the percentage of training data withheld for testing
• num_training_epochs : the number of times the model will be trained on each piece of training data

Training a new CNN model: To finetune a well known model architecture that has been pre-trained on the imagenet dataset, open a terminal and run

  roslaunch geom_rcnn train_cnn_finetune.launch

Important parameters that can be set the 'train_cnn_finetune.launch' file

• all of the same parameters defined in the above section on training a new CNN model, and
• model_architecture : the name of the model architecture. options include: vgg16, resnet and inception

Creating a new dataset: To create a new dataset using the object detection pipeline, open a terminal and run

  roslaunch geom_rcnn dataset_acquisition.launch

IMPORTANT: The space bar is used as a toggle switch to turn on and off the part of the code that saves the training data. Therefore, by default, the code will not immediately start saving data, instead you must press the space bar to turn it on. This also means that you can turn on and off the saving functionality as you augment the position/orientation/lighting coditions of your workspace.

Important parameters that can be set the 'dataset_acquisition.launch' file

• xmin, xmax, ymin, ymax, zmin, zmax : parameters for point cloud passthrough filters.
• category : the current object category label. that is, if you are capturing data related to the object category 'apple', this parameter would be 'apple'
• data_dir : the same basedirectory directory described in the training instructions. this code will automatically create the structure described in that section.
• init_idx : stored images will be labeled by their index. each sequential image will be labeled as such numerically. if you have already stored some data for a given object class, it is a good idea to set this value to a high number so as not to overwrite previous data
• rate : the number of images stored per second.

To create a multi-object dataset, you should collect data on each object seperately. For best results, you'll want to capture many images of each object class at different positions, from different orientations and under different lighting conditions. You can choose to move the object between runs of this launch file, or you can move the object while the code runs and retroactively remove images that includes poor data (such as your arm).

Important ROS topics

There are a number of topics used in the Geom R-CNN pipeline to pass messages between nodes, however the most imporant one for adding Geom R-CNN into your system is the '/detections' topic. Each message includes a string representing the object class and a geometry_msgs/Point representing the centroid of the object in 3D. To see the output of the system, open a terminal and run

 rostopic echo /detections

To see how often messages are being published on the '/detections' topic, open a shell and run

 rostopic hz /detections

License

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