Examples of map legends. 

Context in source publication

Context 1

... primarily of thematic layers of historical content from raster background, or by importing vector data from the reference dataset (e.g. hydrography, current border lines). Reference data layers were created primarily from publicly available sources of geographic data, but with careful check-up and possible modification of data – such as Natural Earth (hydrography) or EuroStat (current borders, towns etc.). An important aspect of the work was connection of appropriate attributes to facil- itate correct production of maps depicting different periods of time (e.g. year of founding of water dams). For a digital terrain model which later served to visualize shading and color hypsometry, data from available sources (SRTM30, CleanTOPO) were used. Generally usable reference data have been stored in two variants with different level of generalization, usable in smaller details for Europe or in larger scales for Central Europe, or the Czech Republic. The data model allows easy tracking of data of individual maps, to share layers between maps and, after its completion, it represents a valuable data base usable both for adding additional content to the maps and for creation of any other similarly oriented cartographic outputs. The visualization of data layers consisted primarily in application of the general map key. In some thematic layers (especially point ones) it was necessary to create a new cartographic symbolization during the work. The color solution of thematic elements was in case of need tailored to the specific content of the map or set of thematically related maps. For the representation of thematic elements using point features mostly basic geometric shapes were used, but a number of intuitive pictograms was also created (e.g. castles, battlefields, machine– and woodworking industry, declaration of independence, seat of ecclesiastical administration, etc.). Pictogram symbols were created in the form of a special cartographic font and could then be shared and used in different sections of the atlas (Fig. 4). Solution to symbology of linear elements was very complicated in some cases. In a large number of maps it was necessary to show different types of boundary, identification and movement related lines in addition to the different time phases of the historical events displayed. Among the most ela- borate in this respect belong the maps showing battles of WW2, where it was necessary to distinguish the lines/arrows symbolizing the movement of combat units with regard to various attributes such as affiliation of units with the fighting parties of the conflict, the type of movement of combat units (attack, advance, transfer, retreat, withdrawal), its intensity (attack major, minor, undifferentiated), a type hierarchy of units (army, brigade, division, group), military units by type of weapons (air forces, tanks etc.), a time period of the war. The resulting solution combines morphological changes in the properties of line characters – size (width) of structure, hue (color) – with variants of line end symbol (arrowhead single or double), placing symbols within lines, and additional text or abbreviation (Fig. 5). Defining the range of area elements in the maps were solved by colors according to the list of symbols; hatch areas were used for overlapping areas. For states, hypsometry with shading or color fill with shading was used; in maps of larger scales (approx. 1 : 500,000 and more), the relief does not appear at all, and if it does, then by more significant elevation dimensions only. The largest share of the work on visualization was creation of labels that were generated directly from the attribute tables of particular feature classes, with the addition of potential exonyms or contemporary names (Fig. 6). Most of the labels (in particular settlements) in ArcGIS were generated par- allel to the geographical grid; a lot of manual work, however, required modification of thematic texts. Due to the large number of heterogeneous maps, a wide group of historians (several dozens of authors) and their individual notions about the presenta- tion of maps it was not possible to fully comply with consistent symbology throughout the atlas. Any deviations are always explained in the particular map legend. From a technical perspective, the visualization was performed by standard symbolizing methods of ArcGIS, without cartographic representations, whose use would require more time to prepare, which, unfortu- nately, was not available. The Academic Atlas of Czech history will contain one main legend explain- ing the general symbols used across all the maps of the atlas, especially general geographical and topographical elements. There will also be local legends attached to individual maps and clarifying specific thematic elements used in the map. In most cases, the legend is placed outside the map frame, with the addition of simple graphic scale and potential other infor- mation relating to the contents of the map (Fig. 7). Small-scale maps are plotted with geographical grid, in medium and large scale maps the grid is absent but the north arrow is added. For DTP preparation, the maps have to be processed in a suitable data format for export. Several types of exports – to PDF with a resolution of 1200 dpi or EPS of 300 dpi were made depending on predominant content of the map. Maps with shaded relief could not be directly exported from ArcGIS as the entire contents at once, because it would prevent proper multiple layers blending and the desired color of elements under the shadow layer would not be properly maintained. Therefore the export took place using separate layers. The bottom layer represents area elements or border edgings, the second layer was shaded relief, and the top layer contained point and line elements along with descriptions. The graphical studio then merged the export layers and layers of shadow with appropriate transparency. Cartographic work on the large Academic Atlas of the Czech History included a series of time-consuming and technically demanding activities. Due to the fact that the point is a historical atlas, the map making is very specific and substantially different from thematic atlas works, containing mainly cartographic presentations of statistical data, as well as from conventional atlases or world regions. The maps have to show not only the physico- geographical or general topographic content layers relative to the specific historical period, but, as a matter of course historical events or situation, often with links to the present state of the region. Thematic elements may then vary in multiple attributes reflecting the quality, quantity and time classification of the displayed phenomena, which should be appropriately cartographically visualized. Close cooperation with historians in the case of the creation of historical maps is essential. Experts in history as the authors of the content side of the map pages are responsible for their factual accuracy. Their efforts include the proper, detailed and comprehensive historical content to the map can sometimes be in conflict with what is real to display in the map of a defined size and scale while respecting the principles of cartography. The use of GIS technology with appropriate tools for cartographic visualization may cer- tainly be recommended; also very important is coordination of appropriate procedures with graphic studio providing professional print of the publication. For the team of cartographers, the creation of historical maps for the historical atlas posed a valuable experience, which would be possible to further develop in the ...