If you use this enhanced cesium-asset package for higher detail NaturalEarthII offline imagery, then you will have issues if you update your Cesium version to 1.18 or more recent, unless you modify the tilemapresource.xml file in that optional path.
You will see what I mean if you diff the
So if you are using cesium 1.18 or more recent, you want to probably change lines 6 and 7 of the optional cesium-assets tilemapresource.xml to read:
Which will bring your optional cesium-assets timemapresource.xml into line with the cesium version of tilemapresource.xml but preserves the level 5 detail of the optional NaturalEarthII imagery.
This might also have similar implications with other imagery that stops working for others versions Cesium 1.18+ and more recent.
Symptoms can include maps that look like they smear or are incorrectly wrapped horizontally east to west or possibly even Segment violations in the browser. Keep this in mind if you start using a recent Cesium version and have imagery or texture issues.