In this paper, the authors give a new representation for virtual reality, which is defined as an intensity-range function on a latitude-longitude plane. It supports three-degree-freedom viewing(yaw, pitch and roll), continuous zooming and walk-through in a virtual enclosed environment. On the basis of the representation, a hybrid approach is addressed for constructing virtual indoor environment, which only requires a sparse set of still photographs and has no strait restriction on taking original photographs. Experiment results show that the approach is robust.