In this paper, an image-based walkthrough system is presented for navigating real-world outdoor scenes based on only three uncalibrated images without reconstructing 3D model. An image-based rendering operation is performed on these sample images and generates photorealistic in-between views in real time. We extend the traditional two-step view morphing to real-time tri-view morphing based on epipolar constraint. Compared with other tri-view morphing methods, our scheme copes well with both complex outdoor scenes and wide baseline scenes, which also poses a qualified alternative to state-of-the-art dense 3D reconstruction. Putting on a head mount display (HMD) like Oculus Rift, user can experience realistic and immersive exploration of real-world scenes.