While you calibrate a building, you have to tap on the screen of Situm Mapping Tool from time to time, in order to indicate your location at that moment.
How to move and where to pinpoint your location?
When you are performing a calibrationg with Situm Mapping Tool, we recommend that you indicate your location:
- At every recognizable point (e.g. doors, columns, entrance to elevators, etc.) or, as a rule of thumb, at least every few dozen meters 10-20 meters.
- At every turn you make (e.g. in corners and intersection). Never change the walking direction between two consecutive points.
- Every time you stop. If you stop, tap your location inmediatelly. If you start walking again, tap again in the same location.
In between those points, you should always move straight and at a steady pace. Situm Mapping Tool will interpolate all the meassurements in between every two calibration points assuming that you move this way.
In the following image, the blue circles represent the best places to tap when calibrating, taking into consideration the building's structure.
How long does each calibration have to be?
There are no inferior or superior limits to the size of each calibration. Here are some recommendations:
- Calibrations should not be longer than 200-500 meters, unless you are an experienced calibrator. If you do something wrong in a certain calibration, you will risk losing a lot of work!
- Calibrations should not be shorter than a few dozen meters. Otherwise, you will probably advance too slowly.
- In general, a good idea is to try to cover small sections of your building at a time (e.g. a hallway, a room or a set of rooms, etc.).
How much should you calibrate?
To know how much you should calibrate & when to stop, you may use the Calibration View Selector (or the Situm Dashboard Configuration page as an alternative).
The (1) Paths selector will give you an idea of the space that you have covered already: please aim to cover all the passable areas of the building, since Situm can only locate the users within the calibrated paths (green paths in the following figure). You may also modify the Path Width to cover more areas with less calibration effort.
You may also click on the WiFi or Bluetooth calibration view, in order to visualize the exact points where WiFi/BLE readings where gathered (each reading may contain the signal of several WiFi APs / BLE beacons gathered at that point). As shown in the following image, you should aim at painting all your building areas in "green" or "orange" at least.
How to maximize the data captured?
You should always aim to capture as much WiFi/BLE signals as possible, within a reasonable calibration cost. There are 2 main strategies to do this: 1) walk slowly, and 2) perform at least calibration passes per area. You should aim at implementing both.
Strategy #1: Walk slowly
Obviously, the slower you walk, the higher the density of signals you will capture. We recommend a walking speed
of 0,50 meter / second - 1 meter / second as a reference. The following figure illustrates the effects of walking slowly.
Strategy #2: Perform at least 2 calibration passes per area
A complementary strategy is to calibrate each area 2 or more times. For example, in corridors this is usually accomplished by calibrating in the two opposite walking directions.
How to make Situm work with most smartphone models?
If you calibrate with just 1 smartphone model, Situm may "overfit" to that particular model: you will get good accuracy with that specific smartphone, but not so much with others.
To avoid this, we recommend that you calibrate each area at least with 2 different smartphone models. This way, you will capture enough signal variability to make Situm robust enough to work with a wide range of smartphone models.