The collision prevention algorithm uses the OBSTACLE_AVOIDANCE message. In this message, the field name ‘distances’ contains the readout of the sensor.
This vector (uint16_t) is for all around the drone. But is it possible to have it all around like a sphere and not like a circle in order to avoid ‘up’ and ‘down’ obstacles as well?
Right now, this is not supported. The local_planner, which emulates a range sensor for the collision prevention use case, would technically be able to provide the data for it. But a mavlink message for it is missing (which would also get huge and probably not be accepted) and the way the collision prevention algorithm works in the Firmware would have to be changed.
The collision prevention was thought to be something very minimalistic that can (in hopefully near future) be used with a range sensor. It could be combined with a distance sensor downwards for terrain following.