# The 3D Product Model Research Evolution and Future Trends: A Systematic Literature Review
## 3 Results
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**S. No** & **3D Product Model Research Themes** & **1940s-1960s** & **1970s** & **1980s** & **1990s** & **2000s** & **2010s** & **2020s** \\ \hline
1 & Product Design & 3 & 4 & 12 & 15 & 3 & & \\
2 & Design for Assembly & 3 & 2 & 15 & 1 & & \\
3 & Data Processing & 2 & 6 & 1 & 2 & 11 & \\
4 & Geometric Dimensioning and Torlancing & 1 & 3 & 1 & 11 & 15 & 3 \\
5 & Assembly Sequence Planning & & 1 & 2 & 9 & 21 & 1 \\
6 & Virtual Assembly/Virtual Reality & & & 6 & 11 & 10 & \\
7 & Assembly line/station layout planning & & & 7 & 6 & 8 & 3 \\
8 & Interpolation between 2D and 3D Models & & & 2 & 4 & 3 & 1 \\
9 & Reverse Engineering/Scanning Technology & & & 2 & 1 & 3 & 1 \\
10 & Assembly Feasibility & & & 1 & 2 & 1 & \\
11 & Web-Based Applications & & & 9 & 4 & 1 \\
12 & Virtual Training/Work Instructions & & & 2 & 9 & 2 \\
13 & Augmented Reality & & & 2 & 12 & 7 \\
14 & 3D Model Library & & & 1 & 11 & 1 \\
15 & Dissassembly & & & & 3 & \\
16 & Artificial Intelligence and Digital Twin & & & & 1 & 7 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Three-dimensional (3D) product model research themes evolution with journal article count. Figure 3: Three-dimensional (3D) product model research themes evolution over time. As the data show, the 3D product model started as a tool mainly used for product design all the way through the 1990s. In the 1990s, virtual reality and virtual assembly began to be discussed, along with the idea of using the 3D model beyond just product design for applications in assembly line and assembly station layout planning. In the 2000s, the research focused shifted from just designing the product to also designing for assembly. The importance of how 3D product models could assist in geometric dimensioning and tolerancing increased, and the use of 3D product models in virtual environments gained further traction. The 2000s also showed the start of research on how the 3D product model could be used in web-based applications, and early discussions on moving beyond virtual reality to augmented reality began. In the 2010s, the importance of structuring the 3D product models so that the data within them could be more easily processed by computers began to take off. While virtual reality and virtual assembly applications of the 3D product model remained strong, augmented reality and combining the virtual and physical environments gained traction. In addition, with the further development of more 3D product models, the need arose to reduce redundancy in creating 3D product models, and research grew on how to query databases of 3D product models to find already designed parts and assemblies. Deploying the 3D product model to the shop floor via virtual training and virtual work instructions also was a research topic that garnered support. In the 2020s, the concept of the 3D product model applications has seen another shift. While augmented reality remains a relevant topic, much of the research has moved to the application of the 3D product model in artificial intelligence and digital twins. The authors' development of the sixteen 3D product model research themes and the categorization, by decade, of the body of knowledge into those themes answers the question of how the 3D product model research has evolved overtime. Then, the 3D product model research themes developed in this work provide the foundation for a future comprehensive 3D product model research ontology.