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skynet-data

A pipeline to simplify building a set of training data for aerial-imagery- and OpenStreetMap- based machine learning. The idea is to use OSM QA Tiles to generate "ground truth" images where each color represents some category derived from OSM features. Being map tiles, it's then pretty easy to match these up with the desired input imagery.

This repository is no longer under active development. We recommend using Label Maker to prepare data instead. That repo contains utility scripts which can be used to replicate the workflow needed to prepare data for skynet-train.

Quick Start

Pre-built docker image

The easiest way to use this is via the developmentseed/skynet-data docker image:

First, create a docker.env file with the contents including your MapboxAccessToken:

MapboxAccessToken=YOUR_TOKEN

Then run:

docker run -v /path/to/output/dir:/workdir/data --env-file docker.env developmentseed/skynet-data download-osm-tiles

docker run -v /path/to/output/dir:/workdir/data --env-file docker.env developmentseed/skynet-data

The first line downloads the OSM QA tiles to /path/to/output/dir/osm/planet.mbtiles. If you've already got that file on your machine, you can skip this.

The second builds a training set using the default options (Roads features from OSM QA tiles, images from Mapbox Satellite). To change the data sources, training set size and other options, add the relevant environment variables to the docker.env file , one per line.

Local docker image

You can also create the docker images yourself using docker-compose. Similarly to the quick-start above, make sure your docker.env file has your MapboxAccessToken and any other environment variables you want to set. Then run:

docker-compose build

to build your local docker image, and

docker-compose run data download-osm-tiles
docker-compose run data

to download the OSM QA tiles, and run the data collection as specified in docker.env. By default the collected data will be saved into the data directory, but you can overide it by using -v /path/to/output/dir:/workdir/data after docker-compose run data similar to the pre-built instructions above.

Variables

The make commands below work off the following variables (with defaults as listed):

# location of image files
IMAGE_TILES ?= "tilejson+https://a.tiles.mapbox.com/v4/mapbox.satellite.json?access_token=$(MapboxAccessToken)"
# which osm-qa tiles extract to download; e.g. united_states_of_america
QA_TILES=planet
# location of data tiles to use for rendering labels; defaults to osm-qa tiles extract specified by QA_TILES
DATA_TILES ?= mbtiles://./data/osm/$(QA_TILES).mbtiles
# filter to this bbox
BBOX ?= '-180,-85,180,85'
# number of images (tiles) to sample
TRAIN_SIZE=1000
# define label classes output
CLASSES=classes/roads-buildings.json
# Filter out tiles whose ratio of labeled to unlabeled pixels is less than or
# equal to the given ratio.  Useful for excluding images that are all background, for example.
LABEL_RATIO ?= 0
# set this to a zoom higher than the data tiles' max zoom to get overzoomed label images
ZOOM_LEVEL ?= 17

You can override any of these parameters in your docker.env and make a full training set using the instructions above.

Details

Install

Sample available tiles

make data/sample.txt

This just does a simple random sample of the available tiles in the given mbtiles set, using tippecanoe-enumerate. For more intelligent filtering, consider using tippecanoe-decode to examine (geojson) contents of each tile.

Labels

Build label images: make data/labels/color or make data/labels/grayscale. Uses the CLASSES json file to set up the rendering of OSM data to images that represent per-pixel category labels. See classes/water-roads-buildings.json for an example. Rendering is with mapnik; see the docs for more on filter syntax.

Images

Download aerial images from a tiled source: make data/images

Heads up: the default, Mapbox Satellite, will need you to set the MapboxAccessToken variable, and will cost you map views!

Preview

Preview the generated data by opening up preview.html?accessToken=<mapbox access token>&prefix=/path/to/data in a local web server.