njroussel/RoadSegmentation

Segmenting satellite images of earth : determining which parts are roads.

Road Segmentation

Collaborators:

• JBouron
• Rimbaud13
• Trofleb

Table of Contents :

• Introduction
• Results
• Setup
  • Python
  • Environment
• Code overview
• Configuration
• Running

Introduction

This project is part of the EPFL "Pattern classification and machine learning" class. More specifically, it is our solution for the second project on road segmentation. This file gives an overview of our code and how it functions. All additional explanations about the project itself can be found in the official paper for it (the paper.pdf file).

The goal of the project is to segment a satellite image of earth by determing which patches of 16x16 pixels are roads or not.

In short, the code runs a first convolutional neural network to get basic predictions. After this it runs a second one, a postprocessing one, which uses the previously computed predictions to give a final prediction.

Results

We achieved about a 0.91 F1-score, below you will find an image illustrating the qualitative result achieved. Every detected road patch is covered in red on the image.

Setup

The machine learning part of the code runs entirely on python. These are our recommendations for the package versions and environment.

Python

These are the python and its packages versions used to produce our results. Python should be available at https://www.python.org/ and it's packages can be found with 'pip' https://docs.python.org/3.5/installing/.

python: version 3.5
matplotlib : version 1.5.3
numpy : version 1.11.2
scipy : version 0.18.1
Pillow : version 3.3.1
tensorflow : version 0.12.0
progressbar2 : version 3.11.0

Environment

These are general recommendations for the environment in which the code runs:

1. If possible use a CUDA enabled GPU. Tensorflow supports CUDA enabled GPUs, which accelerates widely the computation needed by this project. More documentation can be found here.
2. Use a minimalist linux distribution and avoid performing other tasks while the code is running. A typical run of our code is computationally intensive, keeping the amount of resources available to our code as high as possible will reduce its running time. We highly recommend Arch Linux.
3. Here are the datasets. The training set should be at the root of the project in a folder named training/ and the test set should be flattened into a folder named test_set_images/.
4. Do not delete the empty folders in the project, they are needed for outputs. Depending on the environment, our code is not allowed to create the folder by itself, hence our warning about the empty folders.

Code overview

The run.py file is the main file which runs our code from with the parameters found global_vars.py and global_vars_pp.py. The learner.py file contains the main Tensorflow code - it setups the model and runs the validation. logger.py, prediction_helpers, image_helpers, mask_to_submission.py and tf_helpers.py are files which contain helper methods to modularize our code.

Configuration

In the global_vars.py file are all the parameters which will be used for the first neural network. The global_vars_pp.py file contains the parameters for the postprocessing neural network. Documentation about each parameter can be found in the individual files.

The default parameters will load a pretrained model which was built from the other default parameters we provide.

Running

16 GB of RAM + swap space is needed at least in order to run our optimal result (even when loading the model from the files).

Running the code is straight forward - simply use:

python3.5 run.py

in your favorite terminal emulator at the root of the project folder. If you did not change global_vars.py and global_vars_pp.py files, it will load our best model and compute the predictions with them (this should take about 10 mins). However if you decide to relearn the model by yourself, the runtime can take over two hours for our optimal parameters. The run produces the following folders and files :

• test_predictions : Contains the predictions on the images in the test_set_images folder after the first neural network.

• test_predictions_pp : Contains the predictions on the images in the test_set_images folder after the postprocessing neural network.

The predictions for kaggle can then be created by running

python3.5 mask_to_submission.py
or
python3.5 mask_to_submission.py test_predictions_pp/

The first command will create a dummy_submisison.csv file which is computed from the results in test_predictions (without postprocessing). Whereas, the second created the same file but this time from the test_predictions_pp results (with postprocessing).