1. A method for obtaining images for three dimension (3D) reconstruction, comprising: controlling brightness of each of at least two light sources which are spatially separated from each other to be changed periodically, including: among the at least two light sources, there is at least one light source having a period of brightness change different from those of the other light source(s), or the periods of the brightness change of the at least two light sources are the same, but among the at least two light sources, there is at least one light source having a phase of the brightness change different from those of the other light source(s); and using at least three cameras having different spatial positions to capture the images of an object for the 3D reconstruction, respectively, wherein, among the at least three cameras, there is at least one camera starting exposure at a different time from the other cameras, the captured images being utilized to obtain a 3D stereo image of the object, wherein the exposure time of the at least three cameras is comparable to the periods of the brightness change of the at least two light sources, and wherein the exposure time of the at least three cameras is greater than a half of the largest period among the periods of the brightness change of the at least two light sources and less than twice of the smallest period among the periods of the brightness change of the at least two light sources, wherein the half of the largest period among the periods of the brightness change of the at least two light sources is less than twice of the smallest period among the periods of the brightness change of the at least two light sources.