There are two good reasons why a vision document cannot possibly hope to communicate everything. The first is because of the fuzzy front end. A vision document is meant to inspire, but the project could be killed at any point so only a limited amount of work is spent defining the edges of the system. Second, while the vision document may talk about personas, it often does not describe actual system users in the way that a novel might bring a character like Harry Potter to life.
One way to fully realize the environment and characters that will populate your software solution is to take a field trip to sites where the software will be used. Remember the acronym GOOB - Get out of the Building (or -- Get out of the box). Visiting a site brings concrete images to the abstract ideas summarized in the vision document. While it may not be feasible or affordable to bring the entire team on site, even video and phone calls give an enhanced understanding of the environment. The goal is provide a deep impression that will help with development later in the project.
|Developer desk <> a dental operatory|
There are other ways to observe the system: shadowing through screen-sharing sessions, conference calls, setting up role-playing scenarios at work, but none of these bring the situation to life as well as a field trip.