d3-geo VS d3-interpolate-path

This tutorial will show you how to convert publicly available shapefiles to TopoJSON to create interactive maps with d3/d3-geo. I will show you how to do this without the use of the command line so you can get into experimenting with d3 as fast as possible. If you are interested in working with shapefiles and TopoJSON in a more advanced fashion, I suggest you take a look at Mike Bostock’s recent multipart tutorials on command-line cartography.

geographical data handling system

For the globe spinning, I used d3 and topojson to render the world at whatever projection/rotation/etc I give it. Then, using requestAnimationFrame, every frame I slightly rotate the world. Then the "water" behind it is just a blue circle that has hidden overflow.

Using a d3-geo we make projection and a path generator to 'draw' the geographic lines

Thanks for the compliments! The territory data is coming from https://github.com/aourednik/historical-basemaps, I use this data to render an SVG map with D3.js. This is pretty powerful since you can control every part of the rendering mechanism. With D3-geo you can easily do the projections and graticule.

Using d3-transition and d3-interpolate-path I interpolate between the path commands of both datasets.

Source: Schematic transit diagram from Wikipedia: Rotterdam Metro, geographic transit lines from OpenStreetMap Tools used: QGIS for cleaning geographic data, VS Code for editing the schematic SVG, JavaScript, D3.js, d3-interpolate-path

That's a good idea, I've thought of it while making it too. Right now all points in the lines are used as 'control points' for morphing (using d3-interpolate-path for those interested) . Some segments animate a little off because the number of points between the geographic and schematic vary too much. To only morph the segments between stations, I'd have to write a custom interpolation function, which is likely very hard! I might take a shot at it one day though. The other option is to add points to the schematic lines paths (using a tool like SVG path editor), which is very tedious and not very precise either.