The initial mapping process is very hands-on, and can be extremely time consuming. There are many algorithms out there for frontier exploration in mapping, but they generally assume the robot is free to explore the entire space in which it is placed. This doesn't work well with warehouses, as they are often divided into different regions, and the robots will not be used in all of them.
For automated mapping, this creates a chicken-or-egg problem: we need to know where we are so that we don't go outside the area we're supposed to map, but we need a map in order to know where we are.
This can potentially be solved by using warehouse schematics to guide the robot. The robot can attempt to remain localized within the schematic map while it builds the "true" map of the space. This will also enable us to keep it in bounds.