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.