/satellite-image-deep-learning

Resources for deep learning with satellite & aerial imagery

MIT LicenseMIT

Introduction

This document lists resources for performing deep learning (DL) on satellite imagery. To a lesser extent classical Machine learning (ML, e.g. random forests) are also discussed, as are classical image processing techniques.

Table of contents

Top links

Datasets

WorldView

Sentinel

Landsat

Spacenet

Planet

Shuttle Radar Topography Mission (digital elevation maps)

Kaggle

Kaggle hosts over 60 satellite image datasets, search results here. The kaggle blog is an interesting read.

Kaggle - Amazon from space - classification challenge

Kaggle - DSTL - segmentation challenge

Kaggle - Airbus Ship Detection Challenge

Kaggle - Draper - place images in order of time

Kaggle - Deepsat - classification challenge

Not satellite but airborne imagery. Each sample image is 28x28 pixels and consists of 4 bands - red, green, blue and near infrared. The training and test labels are one-hot encoded 1x6 vectors. Each image patch is size normalized to 28x28 pixels. Data in .mat Matlab format. JPEG?

  • Imagery source
  • Sat4 500,000 image patches covering four broad land cover classes - barren land, trees, grassland and a class that consists of all land cover classes other than the above three Example notebook
  • Sat6 405,000 image patches each of size 28x28 and covering 6 landcover classes - barren land, trees, grassland, roads, buildings and water bodies.
  • Deep Gradient Boosted Learning article

Kaggle - Understanding Clouds from Satellite Images

In this challenge, you will build a model to classify cloud organization patterns from satellite images.

Kaggle - other

Alternative datasets

There are a variety of datasets suitable for land classification problems.

Tensorflow datasets

  • There are a number of remote sensing datasets
  • resisc45 - RESISC45 dataset is a publicly available benchmark for Remote Sensing Image Scene Classification (RESISC), created by Northwestern Polytechnical University (NWPU). This dataset contains 31,500 images, covering 45 scene classes with 700 images in each class.
  • eurosat - EuroSAT dataset is based on Sentinel-2 satellite images covering 13 spectral bands and consisting of 10 classes with 27000 labeled and geo-referenced samples.
  • bigearthnet - The BigEarthNet is a new large-scale Sentinel-2 benchmark archive, consisting of 590,326 Sentinel-2 image patches. The image patch size on the ground is 1.2 x 1.2 km with variable image size depending on the channel resolution. This is a multi-label dataset with 43 imbalanced labels.

UC Merced

AWS datasets

Quilt

  • Several people have uploaded datasets to Quilt

Google Earth Engine

Weather Datasets

UAV & Drone datasets

Synthetic data

Interesting deep learning projects

Raster Vision by Azavea

RoboSat

  • https://github.com/mapbox/robosat
  • Semantic segmentation on aerial and satellite imagery. Extracts features such as: buildings, parking lots, roads, water, clouds
  • robosat-jupyter-notebook -> walks through all of the steps in an excellent blog post on the Robosat feature extraction and machine learning pipeline.
  • Note there is/was fork of Robosat, originally named RoboSat.pink, and subsequently https://neat-EO.pink although this appears to be down/archived

DeepOSM

DeepNetsForEO - segmentation

Skynet-data

Techniques

This section explores the different techniques (DL, ML & classical) people are applying to common problems in satellite imagery analysis. Classification problems are the most simply addressed via DL, object detection is harder, and cloud detection harder still (niche interest).

Land classification

Assign a label to an image, e.g. this is an image of a forest.

Semantic segmentation

Whilst classification will assign a label to a whole image, semantic segmentation will assign a label to each pixel

Change detection

Monitor water levels, coast lines, size of urban areas, wildfire damage. Note, clouds change often too..!

Image registration

Image registration is the process of transforming different sets of data into one coordinate system. Typical use is overlapping images taken at different times or with different cameras.

Object detection

A typical task is detecting boats on the ocean, which should be simpler than land based challenges owing to blank background in images, but is still challenging.

Cloud detection

A subset of the object detection problem, but surprisingly challenging

  • From this article on sentinelhub there are three popular classical algorithms that detects thresholds in multiple bands in order to identify clouds. In the same article they propose using semantic segmentation combined with a CNN for a cloud classifier (excellent review paper here), but state that this requires too much compute resources.
  • This article compares a number of ML algorithms, random forests, stochastic gradient descent, support vector machines, Bayesian method.

Wealth and economic activity measurement

The goal is to predict economic activity from satellite imagery rather than conducting labour intensive ground surveys

Super resolution

Super-resolution imaging is a class of techniques that enhance the resolution of an imaging system. Very hot topic of research.

Pansharpening

Image fusion of low res multispectral with high res pan band.

Stereo imaging for terrain mapping & DEMs

Measure surface contours.

Lidar

NVDI - vegetation index

SAR

Image formats, data management and catalogues

STAC - SpatioTemporal Asset Catalog specification

The STAC specification provides a common metadata specification, API, and catalog format to describe geospatial assets, so they can more easily indexed and discovered. A 'spatiotemporal asset' is any file that represents information about the earth captured in a certain space and time. (from intake-stac docs)

State of the art

What are companies doing?

Online platforms for Geo analysis

  • This article discusses some of the available platforms -> TLDR Pangeo rocks, but must BYO imagery
  • Pangeo - open source resources for parallel processing using Dask and Xarray http://pangeo.io/index.html
  • Airbus Sandbox -> will provide access to imagery
  • Descartes Labs -> access to EO imagery from a variety of providers via python API -> not clear which imagery is available (Airbus + others?) or pricing
  • DigitalGlobe have a cloud hosted Jupyter notebook platform called GBDX. Cloud hosting means they can guarantee the infrastructure supports their algorithms, and they appear to be close/closer to deploying DL. Tutorial notebooks here. Only Sentinel-2 and Landsat data on free tier.
  • Planet have a Jupyter notebook platform which can be deployed locally and requires an API key (14 days free). They have a python wrapper (2.7..) to their rest API. No price after 14 day trial.
  • Earth-i Spectrum appears to allow processing of imagery, with the capability to perform segmentation, change detection, object recognition. This promo video contains some screenshots of the application.

Free online computing resources

Generally a GPU is required for DL, and this section lists a couple of free Jupyter environments with GPU available. There is a good overview of online Jupyter development environments on the fast.ai site. I personally use Colab with data hosted on Google Drive

Google Colab

  • Collaboratory notebooks with GPU as a backend for free for 12 hours at a time. Note that the GPU may be shared with other users, so if you aren't getting good performance try reloading.
  • Also a pro tier for $10 a month -> https://colab.research.google.com/signup
  • Tensorflow pytorch can be installed

Kaggle - also Google!

  • Free to use
  • GPU Kernels - may run for 1 hour
  • Tensorflow, pytorch & fast.ai available
  • Advantage that many datasets are already available

Paperspace

Production

Once you have a trained model how do you expose it to the internet and other services? Usually through a rest API. This section lists a number of hosting options.

Custom REST API

Tensorflow Serving

  • https://www.tensorflow.org/serving/
  • TensorFlow Serving makes it easy to deploy new algorithms and experiments, while keeping the same server architecture and APIs. Multiple models, or indeed multiple versions of the same model, can be served simultaneously. TensorFlow Serving comes with a scheduler that groups individual inference requests into batches for joint execution on a GPU

Pytorch serve

AWS sagemaker

Paperspace gradient

chip-n-scale-queue-arranger by developmentseed

Useful open source software

  • QGIS- Create, edit, visualise, analyse and publish geospatial information. Python scripting and plugins.
  • Orfeo toolbox - remote sensing toolbox with python API (just a wrapper to the C code). Do activites such as pansharpening, ortho-rectification, image registration, image segmentation & classification. Not much documentation.
  • QUICK TERRAIN READER - view DEMS, Windows
  • satpy - a python library for reading and manipulating meteorological remote sensing data and writing it to various image and data file formats
  • Pyviz examples include several interesting geospatial visualisations
  • torchvision-enhance -> Enhance PyTorch vision for semantic segmentation, multi-channel images and TIF file,...
  • dl-satellite-docker -> docker files for geospatial analysis, including tensorflow, pytorch, gdal, xgboost...
  • Geowombat -> geo-utilities applied to air- and space-borne imagery, uses Rasterio, Xarray and Dask for I/O and distributed computing with named coordinates
  • TorchSat is an open-source deep learning framework for satellite imagery analysis based on PyTorch.
  • AIDE V2 - Tools for detecting wildlife in aerial images using active learning
  • xarray-spatial: Fast, Accurate Python library for Raster Operations. Implements algorithms using Numba and Dask, free of GDAL
  • geemap: A Python package for interactive mapping with Google Earth Engine, ipyleaflet, and ipywidgets. See the Landsat timelapse example
  • s2p -> a Python library and command line tool that implements a stereo pipeline which produces elevation models from images taken by high resolution optical satellites such as Pléiades, WorldView, QuickBird, Spot or Ikonos
  • felicette -> Satellite imagery for dummies. Generate JPEG earth imagery from coordinates/location name with publicly available satellite data.
  • Land Cover Mapping web app from Microsoft
  • sat-utils/sat-search -> Sat-search is a Python 3 library and a command line tool for discovering and downloading publicly available satellite imagery using STAC compliant API
  • rio-cogeo -> Cloud Optimized GeoTIFF (COG) creation and validation plugin for Rasterio.
  • Solaris -> An open source ML pipeline for overhead imagery by CosmiQ Works, similar to Rastervision but with some unique very vool features
  • aiocogeo -> Asynchronous cogeotiff reader (python asyncio)
  • rio-color -> Color correction plugin for Rasterio
  • NumpyTiles -> a specification for providing multiband full-bit depth raster data in the browser
  • PyShp -> The Python Shapefile Library (PyShp) reads and writes ESRI Shapefiles in pure Python

Movers and shakers

  • Adam Van Etten is doing interesting things in object detection and segmentation
  • Ankit Kariryaa published a recent nature paper on tree detection
  • Chris Holmes is doing great things at Planet
  • Christoph Rieke maintains a very popular imagery repo and has published his thesis on segmentation
  • Jake Shermeyer many interesting repos
  • Nicholas Murray is an Australia-based scientist with a focus on delivering the science necessary to inform large scale environmental management and conservation
  • Qiusheng Wu is an Assistant Professor in the Department of Geography at the University of Tennessee
  • Robin Wilson is a former academic who is very active in the satellite imagery space

Courses

Competitions

  • Spacenet 7: Multi-Temporal Urban Development Challenge - registration deadline Oct 28 2020. Track individual building construction over time from Planet imagery, challenge because of the small pixel area of each object, the high object density within images, and the dramatic image-to-image difference compared to frame-to-frame variation in video object tracking.

Online communities

Companies

Jobs

Neural nets in space

Processing on satellite allows less data to be downlinked. E.g. super-resolution image might take 4-8 images to generate, then a single image is downlinked.

About the author

My background is optical physics, and I have a PhD from Cambridge on the topic of Plasmon enhanced Raman spectroscopy. After doing a post doc I left academia and took a variety of roles, from industrial research at Sharp Labs Europe, to medical physics, to building optical telescopes at Surrey Satellites (SSTL). It was whilst at SSTL that I started this repo as a personal resource. I left SSTL, actually was made redundant along with 30% of the company, and after a brief stint at an IOT start up, I now work as a data engineer. Deep learning is currently a hobby, but I have ambitions to move into this domain when the right opportunity presents itself. My own satellite imagery projects are here, and feel free to connect with me on LinkedIn.