DELTA (Deep Earth Learning, Tools, and Analysis) is a framework for deep learning on satellite imagery, based on Tensorflow. Use DELTA to train and run neural networks to classify large satellite images. DELTA provides pre-trained autoencoders for a variety of satellites to reduce required training data and time.

DELTA is currently under active development by the NASA Ames Intelligent Robotics Group. Expect frequent changes. It is initially being used to map floods for disaster response, in collaboration with the U.S. Geological Survey, National Geospatial Intelligence Agency, National Center for Supercomputing Applications, and University of Alabama. DELTA is a component of the Crisis Mapping Toolkit, in addition to our previous software for mapping floods with Google Earth Engine.

Installation

1. Install python3, GDAL, and the GDAL python bindings. For Ubuntu Linux, you can run scripts/setup.sh from the DELTA repository to install these dependencies.

2. Install Tensorflow with pip following the instructions. For GPU support in DELTA (highly recommended) follow the directions in the GPU guide.

3. Checkout the delta repository and install with pip:

   git clone http://github.com/nasa/delta
   python3 -m pip install delta
   

This installs DELTA and all dependencies (except for GDAL which must be installed manually in step 1).

Usage

As a simple example, consider training a neural network to map water in Worldview imagery. You would:

1. Collect training data. Find and save Worldview images with and without water. For a robust classifier, the training data should be as representative as possible of the evaluation data.

2. Label training data. Create images matching the training images pixel for pixel, where each pixel in the label is 0 if it is not water and 1 if it is.

3. Train the neural network. Run

   delta train --config wv_water.yaml wv_water.h5
   

   where wv_water.yaml is a configuration file specifying the labeled training data and any training parameters (learn more about configuration files below). The command will output a neural network file wv_water.h5 which can be used for classification. The neural network operates on the level of chunks, inputting and output smaller blocks of the image at a time.

4. Classify with the trained network. Run

   delta classify --image image.tiff wv_water.h5
   

   to classify image.tiff using the network wv_water.h5 learned previously. The file image_predicted.tiff will be written to the current directory showing the resulting labels.

Configuration Files

DELTA is configured with YAML files. Some options can be overwritten with command line options (use delta --help to see which). Learn more about DELTA configuration files.

All available configuration options and their default values are shown here. We suggest that users create one reusable configuration file to describe the parameters specific to each dataset, and separate configuration files to train on or classify that dataset.

Supported Image Formats

DELTA supports tiff files and a few other formats, listed here. Users can extend DELTA with their own custom formats. We are looking to expand DELTA to support other useful file formats.

MLFlow

DELTA integrates with MLFlow to track training. MLFlow options can be specified in the corresponding area of the configuration file. By default, training and validation metrics are logged, along with all configuration parameters. The most recent neural network is saved to a file when the training program is interrupted or completes.

View all the logged training information through mlflow by running::

  delta mlflow_ui

and navigating to the printed URL in a browser. This makes it easier to keep track when running experiments and adjusting parameters.

Using DELTA from Code

You can also call DELTA as a python library and customize it with your own extensions, for example, custom image types. The python API documentation can be generated as HTML. To do so:

  pip install pdoc3
  ./scripts/docs.sh

Then open html/delta/index.html in a web browser.

Contributors

We welcome pull requests to contribute to DELTA. However, due to NASA legal restrictions, we must require that all contributors sign and submit a NASA Individual Contributor License Agreement. You can scan the document and submit via email. Thank you for your understanding.

Important notes for developers:

• Branching: Active development occurs on develop. Releases are pushed to master.

• Code Style: Code must pass our linter before merging. Run scripts/linter/install_linter.sh to install the linter as a git pre-commit hook.

• Unit Tests: Code must pass unit tests before merging. Run pytest in the tests directory to run the tests. Please add new unit tests as appropriate.

• Development Setup: You can install delta using pip's -e flag which installs in editable mode. Then you can run delta and it will use your latest changes made to the repo without reinstalling.

Licensing

DELTA is released under the Apache 2 license.

Copyright (c) 2020, United States Government, as represented by the Administrator of the National Aeronautics and Space Administration. All rights reserved.