Recovery of visual structure in illustrated Japanese gardens

摘要

The continued existence of superb Japanese gardens attests to their cultural significance during the last few centuries. Yet despite their special cultural status, factual ambiguities shroud the identity of garden creators, and historical records often omit details about alteration of original compositions. Fortunately some garden illustrations in old texts provide valuable information where original designs have been lost or altered. This paper investigates the depiction of visual perspective in the work of the prolific garden illustrator, Akisato Ritoh, to propose a method for recovery of garden plans from his illustrations. The method capitalizes on the observation that Akisato's work presents rectilinear structures in pseudo-parallel perspective while naturalistic objects are depicted in fronto-parallel views. Visual structure of illustrated gardens is then computed via the medial axis transform, a method used in previous work to reveal global visual structure in the Ryoanji dry rock garden. Three examples show how the approach benefits pattern processing in cultural heritage. The first example provides the visual structure of an unrealized garden that was intended as exemplary of a specific style. The second suggests how fluctuations due to plant growth affect the structural balance of a garden composition. In the third case, plan recovery coupled with medial axis transformation hint at the cultural significance of an inaccessible and relatively unknown garden. Further analysis suggests that abstract visual structure of gardens may serve as a signature of their creators, analogous to the way in which shape of brush strokes may characterize the origins of a painting.