According to Wikitude Developer, in Augmented Reality applications, an object cannot be defined in pixels or similar measurements; the size of the object depends on the distance at which the observer "looks" at the object in the real world; Wikitude's architecture uses Scaled Distance Units (SDUs). SDUs define the relationship between the size of the actual object and the distance at which it is observed.

Let's go to something a little more practical:

• 1 SDU defines that the size of an object is exactly one meter in height and is located 10 meters away.
• 5 SDU defines that the object is exactly 5 meters high and 10 meters away.

Another important point is that as the distance between the object of the physical world and the observer varies, the object defined in SDU can vary its size (smaller the further away the observer is and larger if contrary) and even disappear.

All this can be a bit confusing, what we recommend is to use different values of the SDUs in order to define the size that we consider to be the most appropriate according to the effect that you want to achieve.

You can get the official documentation by clicking here.