# Methods and Applications of Space Understanding in Indoor Environment--A Decade Survey
## 6 Bibliometrics Analysis  
Two subjective feelings accompanied us during the research. The first one concerned the number of articles--the closer to the current year, the more articles were found, and with a visibly growing trend. The second concerned the content of the publications--most of the articles seemed to have similarly referenced basic methodologies or processing.  
To prove these statements, we conducted an additional, purely bibliometric analysis of found publications. The first claim was analyzed with the use of statistical evaluation. To visualize it, we created a year-to-year publication quantities chart, presented in Figure 16. The chart is based on 51 papers selected for full, more detailed analysis. A significant increase in the number of publications regarding the room segmentation and classification topic can be spotted in the last five years. The numbers almost tripled from 13 articles published in the first half of the analyzed period (years 2012-2016) to 37 in the second (years 2017-2021). An extreme outlier of the trend was the year 2020, when the year-to-year ratio reached the level of \(-50\%\). This date coincides with the peak of the COVID-19 pandemic outbreak. The quantity of articles from 2022 is also significantly smaller, but as this survey was conducted before the end of the year 2022 its value should be omitted in the statistics discussion as a not reliable measurement. In this way, the first statement is confirmed. In general, a growing interest in research on the topic of automated room segmentation and classification can be seen, which manifests itself in an increasing number of academic publications discussing it.  
To prove the second statement, we created a reference diagram of the links between the analyzed articles themselves. This part of the bibliometric analysis was based mainly on the widened set of publications, including papers pointed out as important during the survey extension. It constructed a collection of 89 articles, which were analyzed for their linking. By a \"link,\" we mean a citation of an article from the analyzed collection by another article from the collection. To conduct the bibliometric analysis, we used two dedicated applications. VOSviewer was used to obtain the metadata regarding the citations and references [221], and Gephi was used for link visualization [222]. The prepared graph of links between found papers is shown in Figure 17.  
To simplify interpretation, only five articles (with the highest number of links) are presented using their authors' names and year of publication. Including all labels would make the graph unreadable. The counts of links per document varied between 0 and 26. Most references (26) pointed to the article by [PERSON] et al. from 2014 [87]. The following four most referenced works were (in decreasing order) [PERSON] et al. from 2012 [86] with 22 links, [PERSON] et al. from 2016 [1] with 19, [PERSON] et al. from 2011 [112] with 18, and finally, [PERSON] et al. from 2017 [94] with 14 links. For a more comprehensive  
Figure 16: The number of found publications discussing the topic of room segmentation and classification in 2D images per year between 2012 and 2022.  
analysis and trend comparison, the links were also recalculated for the smaller set of articles. There would be only two updates. First, if narrowed to the main flow of the survey (51 articles), just one of the five publications with the most links would be replaced. The difference would be the article by [PERSON] et al. from 2011 being not in the range of accepted publication dates, and [PERSON] et al. from 2020 waqs provided instead [103]. The second change would relate to the order of results: the two first publications would switch places. We consider the second statement as confirmed, likewise the first one. Even after almost a decade, all the newfound articles were intensively referring to one another and with a visible set of well-known base methodologies.