The author presents evolution of views on cartographic generalization since it was defined by until today. It is divided into three chapters which present the evolution of views on cartographic generalization, models of generalization and digital generalization, respectively.
Views on the topic of generalization evolved in the direction of broadening the term itself and towards a different perception of its nature. Originally generalization was understood as a process which can be performed on maps only. Now the prevailing understanding is that it begins earlier, at the conceptual stage of map making. Determination of the method of contents’ presentation is an indication of such generalization.
The character of generalization is another important aspect of the discussion on its nature. The notion of a subjective nature of generalization, expressed, among others, by , was originally predominant. Later there also appeared different opinions, allowing its objectivization (). This direction helped to result in automation of the process of generalization of map contents. Currently a dualism in perceiving generalization can be observed, with a strong bias towards its objective aspect.
In a separate chapter the author discusses conceptual models of generalization proposed by: , , , , , as well as . They are divided into the universal models of theoretical character and those constructed for the purpose of computer automation of the process.
Attempts at digital generalization which currently develop in the context of generalization of general, and especially topographic maps, are discussed separately. Most important algorithms concerning generalization of linear objects are presented chronologically, concluding with a description of comprehensive generalization systems.
The summary presents two main conclusions. Firstly – work on generalization will continue to consider the geographical context during the process. Secondly – generalization of thematic, and especially statistical maps is the prospective direction.
The author’s objective is to present the role of base contents for a statistical map and determine its desired features which would influence optimum perception of the main contents of the map. The article consists of two main parts.
The first part discusses selection of cartographic projection. Presented recommendations could be summarized in a short conclusion that application of equal-area projections is the optimum solution. It results from the necessity of preserving correct spatial relations during the perception of the thematic map contents. It is recommended to show cartographic graticule on statistical maps, for it helps to recognize geometrical attributes of the map and plays the localizing role.
The second part of the article concentrates on the issue of selection of base contents’ elements on statistical maps. Such selection depends on the method of presentation of the thematic contents of the map. Because of that the optimum contents of the map is discussed in the context of basic cartographic presentation methods, i.e. the dot method, the choropleth method, the diagram method and the isoline method. The role of base elements in the process of reading of the main contents is also underlined. It is shown that it is not only the localizing role. Including additional elements of base contents facilitates understanding of the spatial distribution of the phenomenon which is the main topic of the map.
The article encourages extension of the contents of statistical maps by additional elements of contents, which, while keeping correct spatial relations, can improve the efficiency of map use.
This article analyses the accuracy of the presentation of forests on Polish topographic maps. Four test polygons were selected, differing in forest coverage and spatial distribution of forest areas in order to improve the objectivity of the study. All the polygons were located in Roztocze. Four maps were tested: System 1965 (1:50 000), GUGIK80 (1:100 000), PUWG92 (1:10 000), and VMap L2 (1:50 000). The forest areas from the maps and aerial photographs were vectorised; then the photographs were converted into an orthophotomap that constituted the reference material. All materials were coherent in terms of content validity. After vectorising the range of the forests, sampling was conducted within the hexagonal fields. A comparison of the obtained values provided the basis for maps that presented the errors. The analysis permitted several conclusions to be drawn, generally stating that the credibility of maps within the scope of presenting forest areas depends on the scale and purpose of the map, and that any analyses based on these maps should assume that the results should have higher tolerance levels.