Before starting the mapping you should plan the route you will walk to collect the data. The waypoints act as confirmation points for your data collection paths.
The waypoint adding icon is displayed at the bottom right of the mapping screen. Tap this icon and after it has been selected tap the place on the floor plan where you would like to place the waypoint.
When placing your waypoints take advantage of the distinct features of your floor plan such as pillars, doors and stairs to ease the mapping effort. In order to avoid the situation where the position wanders over the walls make sure to leave approximately 1 meter space between the wall and the waypoint.
You can change the position of the already existing waypoints by long pressing the waypoint. This will turn the waypoint into a position marker that can be used to change the location of the waypoint.
Tips and tricks for advanced users
The waypoints are a crucial part of successful mapping. They tie the physical location of the mapper to the floor plan features and landmarks. The waypoint placement should reflect reality as accurately as possible, and for this an accurate floor plan is needed. The floor plan should have enough spatially correct and easily recognizable details and landmarks, such as pillars and corners, that you can align yourself with. Accurate waypoints lead to better paths, better speed estimates, better map, and in the end better localization performance. The easiest way is to add majority of the waypoints before mapping using the web tool. When arriving on the mapping site, you can then add, remove, and move waypoints with MC2 to match reality more accurately.
Some landmarks are natural and excellent places for waypoints. You can easily detect them from the floor plan and align yourself with respect to them. These include:
Entrances, doorways, door frames
Identifiable floor tilings
Dividing walls between stores (e.g. in malls)
Derived and other non-obvious locations
Often easily-identifiable places can be derived from the existing easier waypoint locations:
Opposite wall of a corner or pillar
When walking by, it is easy to verify that you are passing the landmark on the other side of the corridor
Use floor tilings if available: allows using even far-away landmarks
Especially in corridors, also the middle point of two waypoints can be used
Use the grid and measurement tools to align the waypoints if needed
When at the mapping site, look around for surprising details that may be visible in the floor plan:
Electric cable locations, fire extinguishers, etc
Floor and ceiling details (look up and down!)
Good waypoint distance from walls or pillars is about 0.5-1.0 m
Easy to walk by and check-in consistently in the same location
-You can place the waypoints often directly on the landmark, if the landmark is e.g. on the floor
Good waypoint distance from other waypoints is 5-20 m
Too close waypoints do not add much value and make automatic waypoint selection harder
Too far waypoints add error (drift) to the path estimation
Use all corners, pillars, and other easily identifiable landmarks
Consider e.g. the most probable walking direction when placing the waypoints