A method of determining whether a ground is to be re-detected is provided. In an example, the method includes: an i-th gravitational acceleration vector corresponding to an i-th image frame is acquired from a collecting device; when the i-th gravitational acceleration vector changes relative to an (i−1)-th gravitational acceleration vector corresponding to an (i−1)-th image frame, a value is set to a flag bit of the i-th image frame; it is determined whether the collecting device tends to be stable after a motion according to a number of set flag bits in consecutive image frames; when the collecting device tends to be stable after the motion, a similarity between the i-th gravitational acceleration vector and a ground normal vector corresponding to a current ground equation is determined; and when the similarity is less than a similarity threshold, it is determined that the ground is to be re-detected.