We present a compact, image-based representation for three-dimensional architectural walkthroughs. In this paper, we improve upon a cells and portals framework by using images to replace geometry visible through portals (doors and windows) in a three-dimensional model. We present several solutions: images texture-mapped onto the portal, 3D warping of single reference images, and 3D warping of layered depth images. We have achieved significant speedups and present the results of applying the techniques to large architectural models.