## 4 Conclusions  
In conclusion, we have formulated some closing statements and tracked the progress of further research in relevant fields. First, it should be noted that despite the many studies conducted worldwide on the integration and standardization of spatial data, the issue of effective data fusion still needs to be solved. This will mainly be achieved by the continuous development of measurement methods and surveying instruments, as well as by incorporating multi-source data into newly constructed surveying systems. Examples include numerous attempts to combine spatial (geometric) data with physical data. Secondly, scientific progress includes working on new geoid models and continuously improving existing ones. Such studies transform into continuous precision and accuracy validation of local plumb line parameters within the EGM framework. Undoubtedly, this requires ongoing test work using current data sources.  
The results of our study can be summarized as follows:  
* The total station traverse is very well spatially oriented by using the total station vertical axe deflection from normal to GRS 80 ellipsoid components obtained from EGM, and by measuring the coordinates of the total station standpoint using a GNSSreceiver. There is no need to carry out GNSS measurements at any additional merging total station traverse points.
* The proposed methods and algorithms of the sequential online adjustment of the total station positions and the sequential adjustment of the single total station vector of observations, including the GNSS and EGM data in both cases, work correctly. They deliver the same results as the classical offline adjustment of the total station traverse.  
The proposed algorithms allow for real-time surveying with the online adjustment of the observations in the geocentric coordinate system, providing current control of the adjustment results. Our online computation methodology, applied to the discussed surveys (total station/GNSS/EGM), can be used to directly model 3D objects in real time with high spatial accuracy in a geocentric coordinate system. It can also be applied to measure control points for further use in close-range photogrammetry (aerial and terrestrial). The procedure can be applied while defining reliable tie points for merging point clouds in laser scanning (both terrestrial and performed using UAVs). Such an approach is beneficial in BIM while constructing and updating relevant 3D data models.  
As our survey network was near the GNSS reference station (at a distance not exceeding 250 m), we also acknowledge the need to test the solution for other-longer distances. Our future works also encompass testing and improving new, multi-source data algorithms for object diagnostic purposes.  
Conceptualization, K.K. and E.O.; methodology, E.O. and K.K.; validation, K.K. and Z.M.; formal analysis, E.O., K.K. and Z.M.; investigation, E.O., K.K. and Z.M.; writing--original draft preparation, K.K.; writing--review and editing, K.K. and E.O.; supervision, E.O.; project administration, K.K. All authors have read and agreed to the published version of the manuscript. This research received no external funding.  
Not applicable.  
The data presented in this study are available upon request from the co-author [PERSON]: [EMAIL_ADDRESS].  
The authors declare no conflict of interest.