A valid method of virtual scene depth calculating is put forward. In this method cameras rotate in three different viewpoints in the plane and we calculate the depth of panorama using three stitching cylinder panoramas. In the investigation, the column of panorama is regarded as a slot image. Using the conic intersected by the epipolar plane and the cylinder, we can obtain the perpendicularity disparity. In order to obtain dense correspondence fast and accurately, a new method of obtaining horizontal disparity using depth continuity is also put forward. It converts the problem of panorama dense correspondence to the problem of searching points in the conic. The occlusion problem is dealt with using three cylinders in the depth calculation. It is verified that this method is convenient, useful and efficient in calculating the depth of a virtual scene.