A front elevational view of installation of the depth sensor on the rackas shown in FIG. 2 and a side view of installation of the depth sensoron the rack as shown in FIG. 3 both show the rack 10 and the depthsensor 20. Specifically, FIG. 2 illustrates a field of view FOV1 of thedepth sensor, and FOV1 is parallel to the front surface of the rack. Inpractical applications, the FOV1 may be about 90 degrees to cover thefront surface of the entire rack. FIG. 3 indicates another field of viewFOV2 of the depth sensor. In practical applications, the FOV2 can begreater than 20 degrees. For example, the FOV2 may be 30 degrees tocover the front space of the entire rack. The depth sensor can monitorthe rack in the sensing space formed by FOV1 and FOV2, and collect depthinformation and light intensity information in the sensing space.

### Language ###
English

### Assessment ###
The text mentions specific angle measurements for fields of view, with FOV2 being specified as potentially 30 degrees. This could be the basis for a simple factual query.

### Query ###
What is the viewing angle needed to cover the front space of a storage rack?
What is the viewing angle needed to cover the front space of a storage rack?