TopoJson

CesiumJS
1

Hi all,

A bit off topic maybe, and I am not suggesting to include this
format in cesium, but an interesting format and worth watching.

https://github.com/mbostock/topojson

http://sgillies.net/blog/1159/topojson-with-python/

2

Hi Christian,

Thanks for bringing this to our attention. As someone who has dealt with a lot of the inefficiencies that this format addressed, I think TopoJSON looks very promising. I made a note about it on our roadmap.

As for support in Cesium. There’s a few ways that can happen:

  • The format becomes popular enough and/or we get enough requests for it, that we add it.
  • Geoserver adds (or perhaps even already has) support for it, then we can read it using Geoserver and convert it to CZML.
  • Someone in the community - perhaps you - decides it is interesting/important/fun enough that they just add support.
    In terms of implementation, our general strategy is to convert to CZML using czml-writer, which Cesium already knows how to render. We’ve already done so for KML, Shapefiles, and WebGL Globe JSON. However, for TopoJSON, the conversion is likely to lose some of the inefficiencies in the format, so it may be more desired to add support directly to Cesium by using the Cesium API to create polygons, polylines, etc. We’d have to discuss with the folks working more closely with CZML before deciding.

Finally, I am happy to see your interest and focus in formats on this mailing list. We recognize that the ability to visualize content in Cesium is critical to Cesium’s adoption (in fact it is part of the mission statement), and look forward to collaborating with you.

Regards,

Patrick

3

Let’s Make a Map

In this tutorial, Mike Bostock covers how to make a modest map from
scratch using D3 and TopoJSON. It’ll show you a few places where you
can find free geographic data online, and how to convert it into a
format that is both efficient and convenient for display. It won’t
cover thematic mapping, but the map we’ll make includes labels for
populated places and you can extend this technique to geographic
visualizations such as graduated symbol maps and choropleths.

http://bost.ocks.org/mike/map/

4

Christian - thanks for passing this and the other articles along.

Patrick