How do I accurately transition from planning to design?

Hi guys, my first post so I hope I’m not putting anything in the wrong place.

I and my small team of devs have extensively planned a project, but haven’t moved into the practical portion of the creation yet. So we have planned a map in photoshop, but we need to transfer the planned design of the map as accurately into UE4 as possible, which allows us to follow the plan.

Is there any way we can have the exact plan put into Unreal without having to use the tedious landscape sculpting tools?