Machine Interpretation of Line Drawings.pdf

Machine Interpretation of Line Drawings
Kokichi Sugihara
The MIT Press
Cambridge, Massachusetts
London, England
c 1986 by The Massachusetts Institute of Technology
Contents
1 Introduction 1
......................... 1
Philosophy . . . . . ....................... 2
Short History . . . . ....................... 7
Overview of the Book . . . . . . ................ 10
2 Candidates for Spatial Interpretations 13
Polyhedrons and Line Drawings . ................ 13
Classification of Lines . . . . . . ................ 18
Junction Dictionary and Consistent Labeling . . . ...... 21
Hidden-Part-Eliminated Pictures ................ 27
Hidden-Part-Eliminated Pictures ................ 32
Non-Trihedral Objects . . ................ 32
Other Variations . . . . . ................ 34
Other Rules . ....................... 35
Constraint Propagation . . . . . ................ 35
3 Discrimination between Correct and Incorrect Pictures 41
Basic Idea . . . . . . ....................... 41
Planar-Panel Scenes ....................... 43
Extraction of the Spatial Structure . . . . . . . . . ...... 46
Interpretation as a Planar-Panel Scene . . . . . . . ...... 54
Interpretation as a Polyhedral Scene . . . . . . . . ...... 57
Reducing to a Linear Programming Problem . . . ...... 59
Perspective Projection . . . . . . ................ 60
Pictures with Additional Information . . . . . . . . ...... 62
4 Correctness of Hidden-Part-Drawn Pictures 65
Ambiguity in Interpretation . . . ................ 65
i
ii Contents
Face-Layer Structure . . . . . .................. 67
Spatial Structure ......................... 71
Example . . . . . ......................... 73
Realizability of a Polyhedral Scene . . . . . . . ........ 77
5 Algebraic Structures of Line Drawings 81
Degrees of Freedom in the Choice of Objects .