Story mapping is a great visualisation tool for building and sharing your product roadmap. Instead of building it alone, you stand up with your team in front of a white board, build it together via story telling and active discussion. As the result, you end with shared understanding.
The big advantage is the visualisation of a big picture and the focus on a detail at the same time. Details are needed from development perspective, but at the same time, you can stand up together with business folks in front of a map and share the big picture to everyone.
Agile Wheel 