Are approximateTerrainHeights.json and the files under the folder IAU2006_XYS necessary for running?

I find that approximateTerrainHeights.json takes more than 1 second to load. Is it necessary for running Cesium program? In other word,can I delete the file when i deploy my web application?

I also find many json files under IAU2006_XYS folder. Are these files also necessary?

Hi there,

approximateTerrainHeights.json is used to estimate terrain heights when clamping geometry to the ground. If you are not using that option, you should be fine to omit that file.

The IAU2006_XYS files are used when converting between the International Celestial Reference Frame (ICRF) and the International Terrestrial Reference Frame (ITRF), which is mostly used for objects in orbit, so if you are not doing that you may omit those files as well.