Is there a way to get higher resolution tileset than the version of Natural Earth II

I need use Cesium offline.And through the descriptions of the 3 Imagery in Cesium Website,only Natrual Earth II can be used offline,but I think the resolution is not high enough,it's more useful for applications where the viewer is in space.

So is there a way to get tileset which has a higher resolution so that it is enough to view cities in a country.

Hello,

Cesium doesn’t have higher resolution imagery available. We do have a new more levels of Natural Earth imagery available here: https://github.com/AnalyticalGraphicsInc/cesium-assets/tree/master/imagery/NaturalEarthII

If that’s not sufficient, you will need to download your own imagery for offline use.

Best,

Hannah