Parametric modeling of digital human based on Unity
Authors: Chen Xiao , Xu Xiang , Song Xin , Zhang Zhen , Niu Jianwei 
Published: April 2022

Traditional mass manufacturing is unable to meet the needs of customers in the current era of material abundance, and product customization is more popular currently. Online shopping puts forward higher requirements for wearable product customization. This requires manufacturers to accurately and quickly generate consumer models to produce customized products. Human body model is an indispensable auxiliary means in man-machine process, but it has not been paid enough attention to, and its development has certain limitations. What modern product's man-machine design process needs is a kind of human body model that can really participate in the design process and play an evaluation and decision-making role in the calculation, selection and determination of man-machine parameters of product form. Therefore, the parameterized modeling of virtual human body needs to be able to generate the human body model of corresponding geometry and size quickly, which serves for virtual simulation and ergonomics design. The method proposed in this paper is to solve the problem of quickly generating customized digital mannequin. Digital man is the representation of geometric and behavioral characteristics of human beings, the modeling and expression of various characteristics of natural human beings in the virtual world, and the highly digital reconstruction of various biological characteristics of human body. Due to the close relationship with human being, virtual human technology is applied in all aspects of today's society, especially in the military field, aerospace field, aviation field and navigation field. Therefore, how to make virtual human model and movement closer to real people is a hot research topic. Unity is a real-time 3D interactive content creation and operation platform. All creators, including game development, art, architecture, car design, film and television, use Unity to bring their ideas to life. Compared with other digital human modeling platforms such as Siemens Jack, this platform has a great advantage. It can directly import digital human modeled by other modeling software such as Maya and 3Dmax, without the need to preset an initial digital human in the software. This paper realizes the import and parameterization of digital human model based on Unity. First, the import of FBX format digital human model is realized through the simulation environment of Unity development model. Second, linear regression was used to enlarge and shrink the joints of the model in the way of rolling bar to realize the parameterization of the digital human model. Finally, each parameter of the model is displayed in real time, and the model can be parameterized by modifying parameters directly. At the same time, this paper investigated UMA parametric modeling method in Unity. The key parts of this method are Slot, Overlay, DNA and Race. Slot is the mesh, which is the basic unit of character. An Overlay is a texture that is placed over the mesh and acts as the skin of the character. DNA is a set of parameters that change shape rather than biological DNA; Race is a group of slots that links to a specific mesh for men and women. UMA and the linear regression adopted in this paper can not only realize parametric modeling, but also realize skin changing and other functions. However, both the linear regression and UMA proposed in this paper are time-consuming to change the digital human model and there is some error between the model and the real person.