More info about Visibility Analysis & Viewshed

Hi Dear Community,

I’m a developer at a company who are using Cesium. Basic version is not enough for us anymore so we want to buy Cesium ion.

But, I have few questions about Cesium ION SDK:

  1. Does visibility analysis or viewshed tool only work with objects/entities? Is it working with terrain too?

  2. Is there anyone I can contact to get more detailed information?

  3. Can I get a more detailed document, brochure etc.? Because the informations in cesium ion page is not enough for decide to whether buy or not for our company.

It would be great to get contact via email if I could find someone to talk more detailed.

Thanks in advance.