## 4 Conclusions
It is only possible to \"glimpse\" the targets with the Pegasus Backpack, while none detect the 14.5-cm-diameter spheres. Regarding the description of the architectural features, the scanning direction assumes crucial importance: the Stencil's very dense horizontal profiles allow the best interpretation, followed by the Pegasus's dense vertical profiles and then by the Zeb-Revo's \"low\"-density mixed profiles. To best recognize the architectural details through a manual process, the visualization of the data becomes crucial and, for this reason, this aspect was analysed too. Finally, the \"double surfaces\" produced by some of the systems on perfectly vertical and smooth walls were investigated: the Pegasus's histogram of distances from the reference data shows the erroneous presence of twofold surfaces. The results obtained in both the quantitative and qualitative assessments of our examination (Results, Section 3.5) cannot be generalized, in particular the negative ones. Nevertheless, some \"tentative conclusions\" can be outlined regarding the positive characteristics of the three tested systems, while remembering that there is a small difference in instrumental configuration and commercial costs between the Stencil and the Zeb-Revo and that these differences are a lot greater for the Pegasus. The Stencil is the only system we tested that is able to provide data immediately after the acquisition without any post-processing, and that allows the architectural features to be recognized better. The Zeb-Revo output clouds present smaller differences with respect to the reference data and the cross sections agree with the static TLS survey better too. The Pegasus provides the most complete model, with the intensity of the data enabling the identification of artificial features, and it is the only one allowing absolute geo-referencing thanks to the GNSS receiver. To conclude, throughout the presented comparative examination, the IMMS performances and limits were analysed and investigated by testing commercial systems in a real scenario. Since on the market IMMSs are proposed for non-specialists in geomatics, we can imagine some common questionsfrom a generic user interested in evaluating their effectiveness. A first _Frequently Asked Question (FAQ)_ should be: \"How precise is a particular IMMS?\" A quantitative answer is not possible, because the accuracy, for the same system, still depends on the distance between the system and the object and the object may be in a very large open space. A second FAQ could be: \"Which of these IMMSs is the most precise?\" Also in this case, there is no single answer, since a lot of other qualitative aspects in the final results need to be considered. As a general deduction, weighing up the pros and cons, the final judgement on the \"young\" IMMS methodology is extremely encouraging. In the near (imminent?) future, technological and theoretical research in progress will further hardware improvements and software implementations to further enhance this already efficient, albeit not perfect, geomatics system. The authors wish to thank the following companies for providing the tested IMMS products: Me.s.a. s.r.l. as the supplier of the GeoSlam Zeb-Revo; MicroGeo s.r.l. for the Kaarta Stencil; and Leica Geosystems for the Pegasus Backpack. Special thanks go to the architects [PERSON] and [PERSON] for the data processing. For providing access to the location and their helpfulness we thank the Municipality of Florence and engineer [PERSON] of Firenze Fiera S.p.A. Our gratitude also goes to the Italian Military Geographic Institute (IGMI) for the topographic support and to Brig. Gen. [PERSON], Chief of the Geospatial Information Department, for coordinating the activities.