ART+COM's patent was invalidated in 2017 due to prior art from another app called TerraVision from SRI shown in 1994.
I just spent 3 hours on listening to a (German) podcast on the matter with one of the people who developed the algorithm that was copied (addressing scheme for storing and adressing the different LOD tiles in memory, coincidentally the exact scheme Google uses till today, because the guys spent a lot of time optimizing).
The prior art TerraVision had the same name but was a completely different software (military simulation if I understood correctly) and didn't make use of that algorithm.
They still convinced the jury : )