Introduction -- Chapter 1.A Variational Model on Labelled Graphs with Cusps and Crossings -- Chapter 2.Stable Maps and Morse Descriptions of an Apparent Contour -- Chapter 3.Apparent Contours of Embedded Surfaces -- Chapter 4.Solving the Completion Problem -- Chapter 5.Topological Reconstruction of a Three-dimensional Scene -- Chapter 6.Completeness of Reidemeister-type Moves on Labelled Apparent Contours -- Chapter 7.Invariants of an Apparent Contour -- Chapter 8.Elimination of Cusps -- Chapter 9.The Program "Visible" -- Chapter 10.The Program "Appcontour": User's Guide -- Chapter 11.Variational Analysis of the Model on Labelled Graphs -- Bibliography -- Nomenclature -- Index.