visualize-change

A toolkit to visualize changes in OSM, part of the OSM Analytics ecosystem. Currently, this toolkit is not actively being worked on or maintained.

structure

• api - api code (node + mongodb)
• docker - docker related files / configs and shared data volumes
• frontend - frontend code
• server - nginx config (nginx binds frontend and api together and exposes port 8080 in dev, and 80 in production)
• scripts - common scripts
• renderer - electron based offline renderer (gif & mp4)
• tile-processor - crontab and script that download and processes earth QA tiles daily, runs only in production environment

env

Some keys are required for app to work properly:

MAILGUN_API_KEY=...           # api key for mailgun
MAILGUN_DOMAIN=...            # domain from mailgun
MAPBOX_ACCESS_TOKEN=...       # access token for mapbox
SERVER_DOMAIN=...             # main domain of the server (http://SERVER_DOMAIN/), used for making URL in email
POSTGRES_PASSWORD=...         # password to be used for postgres DB
POSTGRES_USER=...             # user to be used for postgres DB
MAP_VECTOR_SOURCE_MAXZOOM=12  # `maxzoom` value used for vector tile source (should be kept to 12)
MAP_LAYER_MINZOOM=12          # `minzoom` value used for roads and buildings layers (for unprocessed tiles should be kept at 12, for processed can be set to 0)

For dev, this could be set in PROJECT_ROOT/.env, for production use it's preffered to export them in the shell.

dev setup

1. yarn install
2. ./scripts/setup-docker-data-folders.sh
3. ./scripts/get-indonesia-tiles.sh (test tiles for dev, final application will use tiles for the whole earth)
4. optionally generated underzoom for tiles (this takes a while) ./scripts/tiles-add-underzoom.sh - env's MAP_LAYER_MINZOOM should be set to 0 if using underzoom
5. yarn run build:dev or ./scripts/build.dev.sh

dev run

1. yarn run start:dev or ./scripts/start.dev.sh
2. open http://localhost:8080

prod setup

1. ./scripts/get-indonesia-tiles.sh (test tiles for now) OR ./scripts/get-earth-tiles.sh (whole earth if you have the hard drive space)
2. ./scripts/setup-docker-data-folders.sh
3. optionally generated underzoom for tiles (this takes a while) ./scripts/tiles-add-underzoom.sh - env's MAP_LAYER_MINZOOM should be set to 0 if using underzoom
4. yarn run build:prod or ./scripts/build.prod.sh

prod run

1. yarn run start:prod or ./scripts/start.prod.sh
2. open http://localhost:8080

dev workflow

Each app should crash on error, and will be picked up by docker and restarted.

On start each app first installs missing deps (yarn install).

All dockerized apps shadow node_modules folder to avoid native code issues (for example Electron installed on macOS wont run in docker).

All dockerized apps in dev mode run file watcher on package.json and re-install (yarn install) deps on changes to that file, in addition to running file watchers that should restart the dockerized app.

offline renderer notes

Exported mp4 are stored in ./docker/data/capture (a docker data volume).

Export flow is as follows:

1. user selected date span, lat & lng coordinates, and provides email for notification when render is finished
2. render button triggers /api/render endpoint, which queues RabbitMQ message for renderer
3. renderer picks up the message, spawns headless electron, and renders frame by frame
4. after all frames are renderer, renderer spawns ffmpeg process to create mp4 file (files are stored in ./docker/data/capture)
5. finally, server is notified back through RabbitMQ, where email is sent to the user

Renderer can be tested on host machine, so the Electron window is visible, to run: yarn run test:local-render providing proper rendering config as JSON, for example:

$ MAPBOX_ACCESS_TOKEN=... yarn run test:local-render '$STRINGIFIED_RENDER_CONFIG'

Where $STRINGIFIED_RENDER_CONFIG should conform to api render config validation.

future work

Possible future enhancements for the project:

• removing rendered mp4/gif files after some timeout (with additional user notification)
• updating step size <-> time span correlation if this is ran on better server (1CPU and 2GB RAM is not enough for reliably rendering a lot of PNG files with Electron and xvfb), 4CPUS and 4GB of RAM gives better results
• combining this with OSM tasking tool