Researches on signed languages still strongly dissociate linguistic issues related on phonological and phonetic aspects, and gesture studies for recognition and synthesis purposes. This paper focuses on the imbrication of motion and meaning for the analysis, synthesis and evaluation of sign language gestures. We discuss the relevance and interest of a motor theory of perception in sign language communication. According to this theory, we consider that linguistic knowledge is mapped on sensory-motor processes, and propose a methodology based on the principle of a synthesis-by-analysis approach, guided by an evaluation process that aims to validate some hypothesis and concepts of this theory. Examples from existing studies illustrate the different concepts and provide avenues for future work.
Alternatively, data-driven animation methods can be substituted for these pure synthesis methods. In this case the motions of a real signer are captured with different combinations of motion capture techniques. Though these methods significantly improve the quality and credibility of animations, there are nonetheless several challenges to the reuse of motion capture data in the production of sign languages. Some of them are related to the spatialization of the content, but also to the rapidity and precision required in motion performances, and to the dynamic aspects of movements. All these factors are responsible for phonological inflection processes. Incorrectly manipulated, they may lead to imperfections in the performed signs (problems in timing variations or synchronization between channels) that can alter the semantic content of the sentence. A detailed discussion on the important factors for the design of virtual signers in regard to the animation problems is proposed in @cite_15 .
@cite_15
2203310485
Virtual signers communicating in signed languages are a very interesting tool to serve as means of communication with deaf people and improve their access to services and information. We discuss in this paper important factors of the design of virtual signers in regard to the animation problems. We notably show that some aspects of these signed languages are challenging for up-to-date animation methods, and present possible future research directions that could also benefit more widely the animation of virtual characters.