A reactive and concurrent control framework for viewpoint control is developed. The viewpoint control task is decomposed into three control objectives namely; obstacle avoidance, visibility and precision. A moving object is tracked in two panoramic sensors using color, and a scalar uncertainty metric of the object position estimate is introduced. Individual control objectives are accomplished by planning paths using harmonic functions and the task is accomplished using a new subject-to composition operator. It is shown that the system is stable under this composition. The system is demonstrated for tracking a human subject using a fixed panoramic sensor and another panoramic sensor mounted on a mobile platform.