This paper shows how to create a small number of natural interpretatio
ns for non-3-D line drawings. If all constraints are removed, there is
an infinite number of possible interpretations. However, humans insti
nctively create a limited number of interpretations. In order to obtai
n these interpretations, it is first necessary to check whether the li
ne drawing requires figural completion. To ensure that natural figural
completion is carried out, restrictions on figural completion, possib
le completion paths, and an actual process for completing figures are
introduced. Next, constraints are introduced to reduce the number of i
nterpretations. These include constraints concerning line elements, du
plication, connectedness, inclusiveness, closure, good figures, and li
ne sharing. The results of a psychological experiment show that the pr
oposed method can create a small number of natural interpretations tha
t correspond to human visual perception fairly well.