proj-vis – A simple web-app tool to quickly visualize what a map projection looks like.

You can find a demo at proj-vis.leifgehrmann.com.

PROJ vs PROJ4

There are two versions of the proj-vis app.

The demo version only supports a limited number of projection classes because it uses Proj4js, a JavaScript port of the proj library. The port doesn't require a web server to transform the coordinates. The list of supported projections classes by alias names can be found here.

The full version supports more projections but requires a web server to transform the coordinates. The server is a small Python script that uses the real proj library to do the transformations. Supported formats include:

• PROJ string
• JSON string with PROJ parameters
• CRS WKT string
• An authority string (e.g. epsg:4326)

Demo version

The demo version requires npm to be installed.

npm ci
npm run dev

Full version

The full version requires npm and docker to be installed.

To start the server, run:

npm run proj-vis-server-build
npm run proj-vis-server-run

In a new shell, run:

export PROJ_VIS_SERVER_URL='http://localhost:7765'
npm ci
npm run dev