This value is a characteristic of the shadow map technique and represents the area for which the shadow is calculated. It is the area captured by the orthographic camera that renders the shadow map.
This value is represented in cm and must be as close as possible to the total size of the objects in the scene. The larger the shadow size, the lower the resolution of the projected shadow. A size that is too small, however, will not encapsulate all the objects in the scene.
* Set shadow size