From the mod page:
"Please check the high quality materials box in your settings, along with max mesh detail to see the map properly, we are working on addressing those issues."

check the high quality materials box in your settings, along with max mesh detail doen't work for me.

What type of graphics card do you use? Mine has trouble with Ark so I use some additional launch parameters.. However if I remove them then I tend to glitch through the world but only on Valhalla because my card can't handle it.. If you would like I can give you my launch parameters and you can try them, but one of them "-sm4" makes the sky always night even during the day.

960 GTX 4 GB. Seems the map update has corrected the graphic map bugs.

Great to hear :) I can't wait till I can afford a better card so I can see the map in all of it's beautiful detail!

Same issues me and my friends encounter when we try to play Valhalla together. All fine in SP. Any way to fix that? It really is no fun falling to death from some suddenly appearing cliff that one could not see before

I'm pretty sure that running a non-dedicated session with other players present requires significantly more RAM, etc, than just a single-player game.
The fuzzy textures and such are caused by the hardware being unable to process everything that's going on. Not to mention, non-dedicated sessions tether players together which is simply hideous, lol.
Your options would likely include upgrading the host's computer (could be quite expensive) or finding a friendly public server to play on.
My server is always open to new players but we do have a lot of mods running so, if that's not to your liking, you might find something more suitable to your tastes elsewhere.

引用自 Iomega0318：

From the mod page:
"Please check the high quality materials box in your settings, along with max mesh detail to see the map properly, we are working on addressing those issues."

i had the exact same problem done what lomega said and updated my nvida drivers and not had a single problem since