Calibration of your Telraam device takes up to 7 to 21 days
If you have the feeling the ratio of cars to large vehicles seems off in the first days and hours after installing your Telraam, this can be explained by the fact that the Telraam requires a calibration period of 7 to 21 days.
The classification of all objects is done based on two parameters, both being speed and distance independent: the fullness value and axis ratio. Based on these two parameters, a distinction is initially made between the category of pedestrians, two-wheelers and cars+large vehicles. The article "Classification: How are different types of vehicles differentiated?" talks about this in more detail. The distinction between cars and large vehicles is then done through a cut-off value. This value is an automatic value during the first week, and then a cut-off value is calculated specifically for your Census window in your house on your street during the calibration period. This specific cut-off point provides a better difference between these two types of vehicles that your Telraam counts on your street.
The calibration happens automatically and the data improves automatically the longer your Telraam is active. This takes at least one week. The shorter the days (and therefore less data), the longer this takes with a maximum of three weeks.
You can assume the sum of the number of cars and large vehicles usually to be correct, but in some cases the distinction between cars and large vehicles is still not correct after the calibration period. The number of cars is then underestimated and the number of large vehicles overestimated, or vice versa. One reason for this may be poor lighting conditions causing long shadows of cars that are then counted as large vehicles. The dividing point between a car and a large vehicle is now roughly around vans. However, it is possible for large cars (SUV, pickup,...) to be counted as large vehicles and small, low vans to be counted as cars.
We therefore ask you to always be careful when using large vehicle count data by Telraam. These data are not as accurate as Telraam data for the sum of cars and large vehicles.