By looking looking at Fig 15-18 we can note that "building information model" moves from an emerging task (Fig.15) to basic knowledge (Fig. 16) in 3 years, it is absorbed by other main keywords in subsequent years (Fig. 17) and it appears as a quite central topic in 2018 (Fig. 18).
4.2.9 Intellectual structure
Observing the co-citation networks, we can find 3 main clusters of sources and their major links, where "automation in construction" plays a relevant role in the field (figure 19). Concerning the authors (figure 20), we can notice 2 main clusters with a centered importance towards "Eastman": indeed, this author is a fundamental reference since he worked on the writing of the "BIM handbook".
Through the factorial analysis of the dataset, it is possible to see which are the most contributing papers to field grouped in two clusters (figure 21): the papers closer to the corners represent the most contributing for the dataset, such as Aydin, Liang, Barazzetti, etc... with higher contribution of papers from cluster 1.