# Usefulness of OSM and BDOT10k Data for Developing Tactile Maps of Historic Parks
## 4 Discussion  
The development of tactile maps is slightly different from the methodology of developing traditional thematic maps. In the process of developing maps of parks in different styles, the data are subject to significant generalisation. An additional difficulty in the present research resulted from the fact that park maps were to be developed for different levels of detail. This required developing an original and coherent set of cartographic characters. Each park style has individual characteristics to be shown on the map [44]. Therefore, a hierarchical division had to be used to maintain coherence between the content ranges used to develop general maps (the first level) and detailed ones (the second level). Semantic coherence between content elements in different park styles was also necessary. The subject literature mainly presents satellite data used for the development of traditional thematic maps. Unfortunately, there is a gap in the literature when it comes to assessing the usefulness of data for the development of tactile maps. The methodology presented in the article is universal; it can be used for tactile maps on various topics. The Data Usefulness Index can be used even when the number of categories in the assessment of data usability has been changed. An additional stage in the process of data evaluation was selecting layers for the analysis. Since one element could occur on several layers, it was necessary to conduct an in-depth preliminary analysis of all layers and descriptive attributes. The results of such in-depth analyses are included in the literature, discussing the thematic layers of BDOT and OSM databases and their attributes, which can be used in the development of tactile maps of parks [45]. However, tall vegetation, for example, characteristic of the Landscape/English style, is marked on several layers in the BDOT10k database: PT--land cover, attribute PTLZ--forest, wooded area with PTLZ01--forest, PTLZ02--grove, and PTLZ03--trees. In turn, in the OSM database, tall vegetation is on the following layers: Gis_osm_landuse (attribute: Fclass--Forest) or Gis_osm_natural (attribute: Fclass--Wood). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Park Style**} & \multicolumn{2}{c}{**Level 1**} & \multicolumn{2}{c}{**Level 2**} & \multicolumn{2}{c}{**Level 3**} \\ \cline{2-7}  & **Bdot10k** & **OSM** & **Bdot10k** & **OSM** & **Bdot10k** & **OSM** \\ \hline Baroque & 0.53 & 0.55 & 0.45 & 0.39 & 0.28 & 0.22 \\ Renaissance & 0.47 & 0.45 & 0.45 & 0.45 & 0.21 & 0.15 \\ Landscape/English & 0.66 & 0.50 & 0.49 & 0.55 & - & - \\ Romantic/Sentimental & 0.75 & 0.80 & 0.51 & 0.58 & - & - \\ Oriental/Japanese & 0.35 & 0.38 & 0.32 & 0.36 & 0.16 & 0.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: DUI values for individual park styles, for three levels of map detail. Analysis showed that both databases--OSM and BDOT10k--can be equally useful in developing tactile maps of historic parks, which provides an answer to the first research question. Results show that usefulness of the databases is very similar. The level of usefulness varies slightly, depending on the level of detail of the maps or park styles. When analysing the map detail levels, a slight advantage for BDOT10k can be noticed, especially with the data on the first and the second levels of map detail. This is confirmed by DUI taking almost the same values for BDOT10k and OSM (0.49:0.48 at the first level and 0.40:0.38 at the second level). The advantage of BDOT10k is somewhat more pronounced at the third map level, when DUI is 0.27:0.20 in favour of BDOT10k. A similarly slight advantage of BDOT10k can be noticed when analysing data for park styles. The obtained values also give us an answer to the second research question. On the basis of the above data, it can be estimated that analysed databases can be useful to obtain up to 50% of the items the first and second levels and no more than about 25% of elements on the third level of map detail.