7.4 Movements

Hand movements are an integral part of sign language, and therefore a substantial part of SignWriting. They are codified with paths and arrows that iconically depict the 3-D movements of the hands in the page. To properly encode 3-D space in 2-D writing, they use graphical attributes to distinguish between planes of movement.

In the digital typographies of SignWriting, there are tens of thousands of characters to account for a wide variety of possible trajectories and types of movement. When devising an annotation schema for movement, and especially when dealing with handwritten SignWriting, using a flat classification is unpractical.

Therefore, in this corpus, movements are annotated by decomposing them into segments, and annotating the segments. These segments convey either straight (STEM) or curved (ARC) paths, and end of movement markers or “arrow heads” (ARRO). Additionally, since the shoulders and waistline are depicted in SignWriting with straight lines, they are provisionally annotated as STEM. The forearm shares many characteristics of STEMs, so it too is annotated as such.

Movement segments have directional information, annotated in their ROT tag, and plane distinctions, annotated in the SHAPE tag. Arrow heads have directional information as well, annotated in the ROT tag, but the SHAPE tag is used to annotate the type of arrow head, which is used in SignWriting to denote what hands move along each path.

Segments often overlap, depicting for example crossing movements of the hands, or a curved segment can be superposed over a straight segment to convey rotation simultaneous to displacement. If these segments have different CLASSes, their bounding boxes are annotated as usual. If the CLASS is the same, the overlap in bounding boxes can make them meaningless. This is very common with crossed forearms configurations, or with X-shaped movements. In these cases, straight segments are subdivided, and each division annotated independently, as in Figure 7.2.

7.4.1 ARRO

Arrow heads mark which hand moves, encoded in their SHAPE tag. They can be black (right hand), white (left hand) or j, for both hands joining in the movement. They also point in a cardinal direction, annotated in their ROT tag.

7.4.2 STEM

Straight lines can represent the shoulders or waistline, straight movements, the forearm, or both the forearm and a movement at the same time. Their direction is marked in the ROT tag using cardinal directions. Since they are symmetric, only half of the possible ROT values are used.

To distinguish between vertical and horizontal movements or forearms, STEMs can be single or double, which is annotated in the SHAPE tag. Shoulders and waists are always single.

7.4.3 ARC

Curved paths represent arcing or circular movements.

As in STEMs, single and double paths represent horizontal and vertical planes of movement. This is encoded with the first letter of the SHAPE tag. The second letter is used to determine the amplitude of the movement, and can take three values: q for ‘quarter’, a small arc; h for ‘half’, a bigger arc which covers around half a circle, and f for ‘full’ for fully circular paths. Distinction between q and h can be difficult without underlying understanding of the sign language depicted, but with some practice it becomes more intuitive.

To determine the ROTation of ARCs, two points need to be mentally found. The first one is the center of the circle on which the ARC lies. The second one is the middle point of the ARC segment. ‘Fully’ circular ARCs still have a middle points, since they start and end at the arrow head. Once these two points are determined, the cardinal direction to annotate for the ROT is the direction in which points the segment from the center to the middle point. Table 7.14 will probably make this clearer.