From Primal Sketch to 2.5D Sketch

The primal sketch model (Guo/Zhu/Wu 2003) is a parsimonious, graphical, token representation for generic natural images. Based on this representation, we compute the layered representations (2.1D sketch) and surface (2.5D sketch), following David Marr's conjecture. The 2.5D sketch is also called the needle map (surface normal field), and can be computed through the so-called Shape-from-X (X stands for visual cuescues, such as stereopsis, shading, texture, motion, defocus, photometric stereo, ...).

We studied two projects for computing 2.5D representations based on the primal sketch. The sketchable parts represents the structural primitives, while the non-sketchable parts are filled in through MRF based on a surface-smoothness assumption.

1. Shape from Shading based on primal sketch (Han and Zhu, CVPR 2005)

2. Stereo matching and reconstruction based on primal sketch (Barbu and Zhu, ICCV 2005)