Yoshizawa–Randlett system


The Yoshizawa–Randlett system is a diagramming system used to describe the folds of origami models. Many origami books begin with a description of basic origami techniques which are used to construct the models. There are also a number of standard bases which are commonly used as a first step in construction. Models are typically classified as requiring low, intermediate or high skill depending on the complexity of the techniques involved in the construction.

History

The concept of diagramming originated in the 1797 book “Senbazuru Orikata”, the first origami book ever published. The diagrams in this book were very unclear, and often only showed the end result of the folding process, leaving the folder unsure how the model was created.
Later books began to devise a system of showing precisely how a model was folded. These ranged from an unwieldy set of symbols to a photograph or sketch of each step attempting to show the motion of a fold. None of these systems were sufficient to diagram all models, and so none were widely adopted.
In the 1950s and '60s, Akira Yoshizawa proposed a system of diagramming. He introduced its diagramming notation in his first published monograph, Atarashi Origami Geijutsu in 1954. He employed dotted and dashed lines to represent mountain and valley folds, and a few other symbols such as the “inflate” and “round” symbols. This system caught the attention of Samuel Randlett and Robert Harbin, who added a few symbols such as “rotate” and “zoom in”, and then adopted it as the standard. The Yoshizawa–Randlett system was first described in Samuel Randlett's Art of Origami in 1961. It was then accepted as the default throughout the international origami community, and is still in general use today.

Origami symbols

Basic folds

There are two main types of origami symbol, lines and arrows. The arrows show how the paper is bent or moved. Lines show various types of edges:
The operations shown here are all fairly common. The pleat folds and reverse folds are often done with the two creases at an angle. Reverse folds of a corner are typically used to produce feet or birds heads.
The sink fold is considered an intermediary to high skill. The version shown here is called an open sink and there is another version called a closed sink which generates a triangular pocket with no flaps showing. In simple cases the model can be partly unfolded and then folded with the sink in place.

Compound folds

In origami, there is a series of several bases that many models are created with. In general, "base" refers to any folded paper that immediately precedes final folding and shaping of the model-to-be. The ones listed below are generally accepted as the traditional origami bases.