All of these methods work both in Building or Global mode. When a building has been selected, Situm is able to provide Indoor Positions within that building. Situm provides three methods (mutually exclusive) for computing this indoor geolocation:

1. Situm Indoor. Determines the user’s location in the calibrated areas based on the WiFi/BLE signals detected. 

2. Calibrated Indoor GPS. Determines the user’s location by fusing together the WiFi/BLE and GPS signals of the device, but only in those areas which have been previously calibrated.  

3. Uncalibrated Indoor GPS. Determines the user’s location both in calibrated and uncalibrated areas inside the building’s canvas based on the WiFi/BLE signals and the GPS position. Uncalibrated areas have to be delimited by special geofences.

In any of this methods, there may be times when Situm will not be able to provide a valid Indoor Location, usually because the signals do not match with what is expected in a given building. In this case, Situm will inform that the user is not in any known building.

Mode #1: Situm Indoor

This method is the one recommended by default if the target environment has a good WiFi/BLE coverage. It determines the user’s position in the calibrated areas of a building by matching WiFi/BLE signals received with the calibrations.

The previous figure will help to understand how this mode works: 

• When the user is in the calibrated area, the WiFi/BLE signals will match perfectly with those of the calibrations, and therefore Situm will provide an accurate Indoor Location within that area. Note that the calibrated area may contain indoor & outdoor spaces (e.g. the parking lot). 
• In the middle ground area, some WiFi / BLE signals from the calibrations will still be heard, therefore providing a match (incorrectly).  In this case, Situm will provide an imprecise and often erratic location in the calibrated area. This is common when the user is entering / exiting the building.
• Finally, if the user gets farther away from the building, she will eventually be in the out of building area, where WiFi/BLE signals will not match with the calibrations. Here, Situm will not provide any valid location, just inform that the user is not in any known building after a period of time (see Next Table).

Mode #2: Calibrated Indoor GPS

GPS does not work under roof, but that does not mean that GPS cannot be used in some places within buildings to improve the positioning experience. That includes: opensky areas, floors with glass ceilings, outdoors parking lots within the building canvas, etc. 

If your building contains such areas, and specially if these areas have unsufficient WiFi/BLE coverage, you may want to activate the Calibrated GPS Indoor Mode. This mode fuses GPS with WiFi/BLE signals, returning an Indoor Position both in indoor and outdoor calibrated areas of the building.  The GPS signal will be used as long as it falls within a 100 meters margin from the building’s canvas. 

The following image shows how this mode works: the GPS signal will be mixed with WiFi/BLE in the whole calibrated area (green area), although it will only be relevant in the outdoor space (e.g. parking lot, field), where there's a good GPS signal. Like in the Situm Indoor Mode, Situm will only produce Indoor Locations within the calibrated area. Therefore, when the user is in the middle ground area,  Situm will provide an inaccuate location in the calibrated area. When the user is in the out of building area, Situm will  inform that the user is not in any known building after a period of time (see table of Situm Indoor Mode).

The previous figure will help to understand how this mode works:

• When the user is in the calibrated area, the GPS signal will be mixed with WiFi/BLE, although it will only be relevant in the outdoor space (e.g. parking lot, field), where there's a good GPS signal. Like in the Situm Indoor Mode, Situm will only produce Indoor Locations within the calibrated area. 
• the WiFi/BLE signals will match perfectly with those of the calibrations, and therefore Situm will provide an accurate Indoor Location within that area. Note that the calibrated area may contain indoor & outdoor spaces (e.g. the parking lot). 
• In the middle ground area, some WiFi / BLE signals from the calibrations will still be heard, therefore providing a match (incorrectly).  Even if they don't, the GPS position may fall within the building canvas. Under any of these events, Situm will provide an imprecise and often erratic location in the calibrated area. This is common when the user is entering / exiting the building.
• Finally, if the user gets farther away from the building, she will eventually be in the out of building area. In this area, WiFi/BLE signals will not match with the calibrations, and the GPS signal will be out of the canvas boundaries. Here, Situm will not provide any valid location, just inform that the user is not in any known building after a period of time (see table in Situm Indoor Mode section).

Mode #3: Uncalibrated Indoor GPS

In the previous mode, an user had to calibrate all the outdoor areas of the building where he wanted to use the GPS signal. The uncalibrated indoor mode saves much of this work, by being able to provide positioning both in calibrated and uncalibrated areas of a building, mixing GPS and WIFi/BLE signals in all of them.  

This method requires a simple preconfiguration: the building must contain geofences with a specific configuration in the outdoor areas where the GPS information will be used. This area is represented in blue in the following figure.  

This is how it works: 

1. If GPS is not available, the behaviour is similar to the Indoor Mode.
2. If GPS falls outside a geofence, the behaviour is similar to Calibrated Indoor GPS Mode.
3. If GPS falls one of those geofences (e.g. blue area in the previous figure), the location will be calculated by mixing BLE and GPS (WiFi will be deactivated).

We recommend to use this method with the Building Selection Mode #4: Automatic Selection WiFi/BLE Signals + GPS in geofence.

Comparisson: Pros & Cons of each mode