04 – Positioning

Calibrating the compass #

Situm uses the smartphone compass to enhance the orientation estimation. In order to use the information it provides, the compass needs to be properly calibrated.  You may do this by holding your device in your hand and moving your phone around several times, tracing an “eight-figure” like the one shown in the following image.

Building vs Global Mode #

Situm Mapping Tool lets you test both positioning modes: Building Mode and Global Mode.

ModeDescriptionPosition Type
Building Mode
Computes the geolocation of the user in a building that has to be explicitly selected beforehand.Indoor only.
Global ModeComputes the user location in any of the calibrated buildings or anywhere in the world. This mode detects automatically the calibrated building where the user is (no need to select it explicitly) and provides her Indoor Position. If the user is not in a calibrated building, the Outdoor Location will be rendered. Position could be both Indoor or Outdoor,

Building Mode #

To activate the Building Mode, uncheck the “Enable indoor/outdoor location” option in the Settings screen. 

Then, go to the Positioning screen.  Select your building by clicking on its icon on the map, or by searching for its name on the search bar. 

Finally, down on the right corner, you will find the Positioning icon: click on it to get your current location. Wait a few seconds until you see the blue arrow: this shows your current position and orientation.   

Global Mode #

To activate the Global Mode, check the “Enable indoor/outdoor location” option in the Settings screen.

 After that, you will be able to select your preferred Building Detector.  The following Building Detectors are available:

  1. WIFI/BLE based:
    1. WiFi and BLE (recommended): considers that you are in the building whose WiFi and BLE signals (gathered from calibrations) match better the WiFi and BLE signals perceived by your smartphone. 
    2. WiFi:  similar to the WiFi and BLE Building Detector, but using only WIFI signals instead.  
    3. BLE: similar to the BLE and BLE Building Detector, but using only BLE signals instead. 
  2. GPS based (GPS proximity): considers that you are in the closest building to your GPS location (only if it is close enough).

After you select your favorite Building Detector, go to the Positioning screen.  Unlike in the Building Mode, do not select any building. Instead, click on the Positioning icon. If you are in a building configured with Situm, the selected Building Detector will detect it and after a few seconds you should see your current position and orientation.  Otherwise, your Outdoor location will be rendered.

Indoor geolocation modes #

Situm is able to produce Indoor & Outdoor geolocations. When Situm yields Indoor geolocations, there are 3 main modes that can be used (explained in depth in the article “Indoor geolocation modes“): Situm Indoor, Calibrated Indoor GPS and Uncalibrated Indoor GPS.  

Mode #1: Situm Indoor #

Determines the user’s location in the calibrated areas based only on the WiFi/BLE signals detected (see this explanation for more detail). To activate this mode, you will need to deactivate the Positioning Setting “Use GPS for indoor location”. 

  1. Can be on/off
  2. Must be off

Under this mode, Situm Mapping Tool (see the previous figure) allows you to select which one to use: 1) only WiFi, 2) only BLE, 3) both WiFi and BLE (recommended). WiFi and BLE are the most important sensors that can be used to yield a high accuracy experience. It is recommended that, if you have calibrated your building with WiFi and BLE, you use both signals for positioning. The following image represents a building that has been calibrated both with WiFi and BLE.

Wifi Positioning Model
BLE positioning model

This can be useful to see, for instance, how Situm positioning will work in your building if you enable/disable one of them.  In the Positioning menu, the number of WiFi APs and BLE beacons scanned is updated in real-time (1). By clicking on the dialog, you may see all the BLE beacon (2) and WiFi (3) scans, updated in real-time.


Mode #2: Calibrated Indoor GPS #

This mode 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 (see this explanation for more detail).  

To activate it, turn ON the “Use GPS for indoor location” option on the Positioning Settings. This will allow Situm to fuse the GPS information (with WiFi / BLE) all the time as another information source. When the smartphone is below roof, the GPS information will be of low quality and therefore will be of low importance, but when the GPS is under open sky, the GPS will become more important and help get a better location experience.

  1. Can be on/off
  2. Must be on

Like with WiFi / BLE, Situm will only render valid geolocations within calibrated areas. This means that you will need to calibrate outdoor areas such as roofs or parking lots where you want Situm to use GPS information. For example, in the following image we show how we calibrated not only the indoor areas where WiFi/BLE will typically be used, but also the parking lot where GPS will play an important role.  

Calibrated outdoor

This method can be deactivated for all the smartphones in the building by setting a special custom field.

Mode #3: Uncalibrated Indoor GPS #

This method uses GPS data to provide and Indoor Position (it can also be fused with WiFi/BLE signals), but contrary to the previous one, this method can provide positioning both in calibrated and uncalibrated areas. Uncalibrated areas have to be delimited by special geofences (blue areas in the following figure), where GPS will be used without needing to calibrate them. See this explanation for more detail:

a) Indoors calibrated area (WiFi/BLE used, GPS has low influence)

b) Middle ground area

c) Out of building area

d) Outdoors calibrated area (GPS + WiFi + BLE used)

e) Outdoors geofenced area (GPS + WiFi + BLE used)

Therefore, this method avoids the need for calibrating outdoor areas in general. For instance, in the previous section, we explained how we had to calibrate some outdoor areas of the building, such as the parking lot. This time-consuming task can be avoided with the “Uncalibrated Indoor GPS” method.

This method requires two simple preconfigurations. First, turn ON the “Use GPS for indoor location” option on the Positioning Settings.

  1. Can be on/off
  2. Must be on

Second, the building must contain geofences with a specific configuration in the outdoor areas where the GPS information will be used.   After this, Situm will be able to fuse GPS intelligently not only within the calibrated areas, but also within the uncalibrated ones that have been delimited by these geofences.

Like the Calibrated GPS Indoor, this method can be deactivated for all the smartphones in the building by setting a special custom field.

Outdoor positioning #

If the Global Mode is activated, Situm can provide Outdoor Positioning anywhere in the world.  

Situm Mapping Tool allows you to test this feature. To do that, you will have to (1) turn ON the Global Mode and (2) configure your preferred building detector. After that, if you are not in a building calibrated by Situm, your Outdoor Position will be returned (3).  Your location will be updated every few seconds based on the GPS (or location provider) of the smartphone.


Contrary to the previous method (Outdoor GPS based on Building Detector), Situm offers a legacy alternative (not recommended anymore) to decide whether the smartphone is located indoors or outdoors based on the SNR (Signal-To-Noise-Relationship) of the GPS signals it receives (high SNR = outdoors). If the smartphone is located outdoors, then the GPS will be used to render an Outdoor Location.

The bigger the SNR, the higher the chances that the user is outside. The default value is 28, so Situm may work well out of the box in most buildings, but others may require a bit of configuration to decide if the smartphone is indoors or outdoors.

Configuration steps

As detailed in the following figure, in the Positioning Settings, (1) turn ON the Global Mode and the Open Sky Detector. After that, (2) by pressing on “Open sky SNR configuration” and “Overriding the server value” (3), you may configure the Minimum SNR (SNR threshold value):

  1. If the Minimum SNR is too low, it is highly likely that the system will decide that you are outdoors even when you are indoors, especially if you pass nearby areas where GPS can be received (e.g. windows).
  2. If the Minimum SNR is too high, it is highly likely that the system will never be able to detect that you are outdoors, even if you are.

Finally, you may configure the frequency by which the Open Sky detector operates. By default, it is set to reevaluate the GPS SNR every 5-10 seconds, but you may configure this value by activating the Continous Mode and changing the GPS scan interval. The lowest the interval (e.g. 1 second), the highest the accuracy but also the battery consumption. 

Configuring positioning in navigation #

This positioning feature allows for the adjustment of the user’s current position and orientation to align with a selected navigation route. This feature is governed by three key parameters: Route adjustment, distance threshold and angle difference threshold. You can find more detailed information by visiting the following link.


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