Short description of the CZML format
CZML is a JSON format for describing a time-dynamic graphical scene, primarily for display in a web browser running Cesium virtual globe. It describes lines, points, billboards, models, and other graphical primitives, and specifies how they change with time. While Cesium has a rich client-side API, CZML allows it to be data-driven so that a generic Cesium viewer can display a rich scene without the need for any custom code. In many ways, the relationship between Cesium and CZML is similar to the relationship between Google Earth and KML.
The Role of Shapefile in SDDI
Currently, CZML is not being used in the SSD project. Since the 3DCityDB Web Map Client, which is being used in the SSD districts for exploring and interacting with the virtual district models, is based on Cesium virtual globe, it is already capable of supporting CZML. It makes the applications compatible to support and include time-dynamic functionalities (for example, moving objects).
Format Specification
Specification documents: https://github.com/AnalyticalGraphicsInc/czml-writer/wiki/CZML-Guide