This paper describes an efficient method to obtain 3D information from omni images using EPI analysis. Two types of omni cameras are employed to make a spatio-temporal volume, which is a sequence of omni images stacked in the spatio-temporal space. For the EPI analysis of omni image, we examine different types of cross sections in such spatiotemporal volumes. To conduct the EPI analysis realistic, we must find out the cross section on which the vertical straight lines in the real world are preserved as straight lines. We define such cross section as omni EPI. To acquire 3D information using the characteristics of the omni EPI, we propose model based epipolar-plane image (EPI) analysis. To demonstrate the effectiveness of this method, we present experimental result using an omni video of outdoor environments.