For this model of Mercury I used the finished 2012 global map made of the images Messenger took. Further details can be found here: http://messenger.jhuapl.edu/the_mission/mosaics.html
The map I used within the model is at 50% of the size of the original map. I added random annotations of the craters and features on Mercury. If you want to know more about all those features, please visit the Messenger website.