# An Inspection of IFC Models from Practice
## 4 Methodology
### Storage of Georeferencing  
The georeferencing of the models is a priority when dealing with GeoBIM integration, and it was therefore important to point out the current use of such a feature. \begin{table}
\begin{tabular}{l l l l} \hline \hline  & **Country** & **Object** & **Scope** \\ \hline
1a & & & Architectural \\ \hline
1b & NL (Almere) & Building &
\begin{tabular}{l} Structural \\ Installations \\ \end{tabular} \\ \hline
2a & & & Architectural (axis, signals, drainage, containment) \\ \hline
2b & & & Structural (road surface) \\ \hline
2c & & Installations \\ \hline
2d & & & Topography \\ \hline
2e & & & Survey reference \\ \hline
2f & & & Elements for expropriation and heritage \\ \hline
3a & & & Architectural \\ \hline
3b & & Building (metro station) &
\begin{tabular}{l} Structural \\ Installations \\ \end{tabular} \\ \hline
4 & NL (Den Haag) & Building (auditorium) & Architectural \\ \hline
5–6 & & Building & Architectural \\ \hline
7a & & & Architectural \\ \hline
7b & & & Structural \\ \hline
8a & & & Architectural \\ \hline
8b & & & Structural \\ \hline
8c & & & Facade \\ \hline
9a & & & Architectural \\ \hline
9b & & & Structural \\ \hline
9c & & & Context \\ \hline
10 & & & Architectural \\ \hline
11 & & Building & Structural \\ \hline
12 & F (Epêne) & Building & Architectural \\ \hline
13 & SE (Falun) & Building & Architectural \\ \hline
14 & NL (Almere) & Building & Architectural \\ \hline
15 & I (Savigiliano) & Building & Architectural \\ \hline
16–17 & & Building & Architectural \\ \hline
18–27 & & & Building (project A) & Architectural \\ \hline
28 & & & Architectural \\ \hline
29a & & & Architectural \\ \hline
29b & & & Installations \\ \hline
29c & & & Structural \\ \hline
29d–f & & Installations \\ \hline
30a & 1 & Building & Architectural \\ \hline
30b & & Installations \\ \hline
30c & & & Structural \\ \hline
30d–f & & Installations \\ \hline
31 & & & Architectural \\ \hline
32 & & & Architectural \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Synthesis features of the models inspected. Two aspects were considered to analyze the storage of the georeferencing information: first, where the information was stored, according to the Levels of Georeferencing identified by [PERSON] and [PERSON] (2017), with _LoGeoRef0_ in case there was no information at all. It was possible that such information was stored multiple times, according to different _LoGeoRefs_, since at present, no validation system exists to check that information stored according to different _LoGeoRefs_ is kept consistent. An additional hinder for a possible validation is that it was not possible to store metadata related to the used coordinate reference system (CRS) in IFC v.2x3, unless the _EPset_ProjectedCRS_ and _EPset_MapConversion_ ([[https://forums.buildingsmart.org/t/geolocation-standards-in-ifc2x3-and-ifc4/2329](https://forums.buildingsmart.org/t/geolocation-standards-in-ifc2x3-and-ifc4/2329)]([https://forums.buildingsmart.org/t/geolocation-standards-in-ifc2x3-and-ifc4/2329](https://forums.buildingsmart.org/t/geolocation-standards-in-ifc2x3-and-ifc4/2329)), accessed on 1 March 2021) are used, which is not a very spread system though. Therefore, it would be hard to check reciprocal consistency. The storage and quality of the information about North and East coordinates values, the elevation values and the rotation direction were checked and reported separately, since it resulted to be not very usual for the three of them to be stored consistently. Moreover, the quality of the information stored in each level was checked with respect to the ground truth in the available documentation and classified as:  
**Accurate**: referring to the actual location of the construction (green in Table 3);  
**Close approximation**: identifying a point in the same city than the construction (yellow in the table);  
**Far approximation**: identifying a point in the same country than the construction (orange in the table);  
**Wrong**: (red in the table).