We describe a system for interactively acquiring depth for an image-based representation of a single input image. We use layers of images with depth to represent the scene. Unlike traditional 3D modeling and rendering systems that require precise information that are usually difficult to model and manipulate, our system's emphasis is on ease of use, comprehensiveness, and use of potentially crude depth information.
Depth is extracted by the user through intuitive tools using the powerful notion of selection.
Once a set of pixels is selected, the user can assign depth by painting and chiseling, using shape from shading, applying filters, aligning and extracting shape from geometry primitives, or using level set methods. The ground plane tool provides an intuitive depth reference for all other tools and serves as an initial step in depth specification. Our system is based on pixels and selections, and therefore does not impose any restriction on the scene geometry. The user can interactively perform depth operations on SGI O2s and Octanes. This video demonstrates techniques for modeling and rendering urban environments.