# Methodology for Conceptual Navigational 3D Chart Assessment Based on Eye Tracking Measures
## 4 Discussion  
On the basis of the research carried out and the results obtained, it can be concluded that it is possible to develop a universal indicator with which to assess the effectiveness of a navigation map. It should be noted here that the universal indicator is based on a decision-making method of calculating a numerical advantage after summing the values obtained for the scenarios tested, which is quantitative in nature. Therefore, differential indicators should be additionally analysed in order to assess the partial advantage of the concept map in terms of readability, correct identification, and time. On the basis of previous research on conceptual 3D maps, it can be stated that the proposed method offers clear advantages over purely survey-based approaches. In the work of [58], admittedly, the surveys made it possible to demonstrate that this type of visualisation is useful (at the level of'very important' or 'worth having'), but it is difficult to clearly state whether such declarations of map effectiveness are sufficient to justify further work on new forms of presentation, interface changes, or improvements to the visualisation system. The use of the proposed universal indicator allows for a quantitative analysis of the effectiveness of the maps based on quantitative data, which allows for a more structured evaluation. The final methodology, which includes a universal indicator, also allows for a more detailed assessment using W, ID, and T indicators, among others, which can be analysed according to the objectives of the study. Compared to other eye-tracking measures, the improvement in performance evaluation lies in the reduction of multiple measures, such as the number of saccades, fixations, or heatmap analysis, customarily used in research [48; 49; 50], to a single indicator strongly correlated with them. The advantage of this method compared to other approaches using single or composite analytical indicators [66] is the direct inclusion of information about the distribution of attention in the form of a heatmap. The limitation of a universal indicator is certainly its quantitative nature. It does not take qualitative aspects into account; nevertheless, at this stage of the research, this can be seen as a compromise to enable a quick comparison of the effectiveness of the maps. The next limitation concerns the perception of the navigation map in terms of 100 per cent efficiency. A universal indicator only reveals a quantitative advantage but does not capture important cases, such as the difficulty in identifying an object or the increased time it takes to find it on the map. Therefore, qualitative evaluation methods based on a case-by-case analysis should be used to achieve this goal. However, this limitation can be overcome by using a more elaborate methodology, as described later in this section. Another limitation relates to the need to use spatially similar test scenarios, which is, however, necessary for meaningful comparison. The difficulty in this case lies in the selection of area-similar scenarios for the 2D and 3D maps. The adopted method limits the use of any perspective views possible in 3D scenery, but we, nevertheless, believe that a full-scale test of the 3D map should be carried out once its fundamental advantage in efficiency has been established. Visual assessment methods often lead to interpretative ambiguities. Although some scenarios indicated that the 2D map was most effective, some indicated that the 3D map was more effective, and some indicated that there were no differences. Given the problematic nature of using a visual and survey method for a series of maps, the proposed approach offers a clear advantage in the decision-making process, as it is based on concrete numerical values. Post-test questionnaires are common tools for evaluating the solution under test.