ABSTRACT To preserve and restore ecosystems, public environmental policies on the international level now encourage the creation of Green Infrastructure, i.e. networks composed of areas where animal and vegetal species can live (habitat patches) and corridors to circulate between them. In France, each regions, the first subnational administrative level, identified existing habitat patches and corridors in their territories using flexible guidelines. This resulted in heterogeneous data, raising the question of their consistent mapping at a supra-regional level. To answer this question, this study first focuses on the habitat patches of two adjacent regions and explores three ways of homogenizing the map. The first method consists in generalizing the more detailed data using morphologic operators. The second method consists in graphically refining the less detailed data by filling the areas with patterns taken from the more detailed data. The third method consists in drastically changing the level of abstraction of the data from both regions by rasterizing the space. Based on those experiments, we applied the most appropriate method to data collected by all the regions of continental France, a step which itself raises new issues concerning data harmonization and parameters settings.

ABSTRACTMapping applications display multi-scale maps where zooming in and out triggers the display of different maps at different scales. Multi-scale maps strongly augmented the potential uses of maps, compared to the traditional single-scaled paper maps. But the exploration of the multi-scale maps can be cognitively difficult for users because the content of the maps can be very different at different scales. This paper seeks to identify the factors in the design of map content and style that increase or decrease the exploration cognitive load, in order to improve multi-scales map design. We studied sixteen existing examples of multi-scale maps to identify these factors that influence a fluid zooming interaction. Several different analyses were conducted on these sixteen multi-scale maps. We first conducted a guided visual exploration of the maps, and a detailed study of the scales of the maps, to identify general trends of good practices (e.g. the WMTS standard that defines zoom levels is widely used) and potential ways of improvement (e.g. a same map is often used at multiple successive zoom levels). Then, we focused on the visual complexity of the multi-scale maps by analyzing how it varies, continuously or not, across scales, using clutter measures, which showed a peak of complexity at zoom level 12 of the WMTS standard. Finally, we studied how buildings and roads are subject to abstraction changes across scales (e.g. at what zoom level individual buildings turn into built-up areas), which can be one of the causes of exploration difficulties. We identified some good practices to reduce the impact of abstraction changes, for instance by mixing different levels of abstraction in the same map.

ABSTRACTThis paper reports on a new Area Preserving Segment Collapse (APSC) algorithm for simplifying polygonal boundaries while preserving the polygonal area at simplified target scales and minimizing areal displacement. A general segment collapse algorithm is defined by iteratively collapsing segments to Steiner points in priority order, guided by placement and displacement functions. The algorithm is specified by defining functions that minimize areal displacement under the constraint that the areas of adjoining polygons are preserved exactly. Self-intersections can be avoided by testing for intersections with two new line segments associated with each segment collapse operation. The paper demonstrates simplification results for a sample of 10 lakes formed from alpine, Karst, glacial and arid desert processes as well as artificial dams. APSC results are compared with three other simplification routines and evaluated for area preservation, linear and areal displacement, complexity and introduction of boundary self-intersections. Results confirm that the APSC algorithm preserves area exactly and indicate that it outperforms the other tested algorithms for minimizing areal displacement while producing reasonably low measures of linear displacement. Self-intersections can occur more commonly with APSC than other algorithms but are avoided with the proposed topology check. The APSC algorithm additionally preserves polygon complexity better than other tested algorithms.

ABSTRACTZooming is a basic operation that many digital maps support for exploring them interactively. Especially for maps on small screen devices, this is a helpful operation to uncover the user's region of interest possibly hidden by labels, e.g. points of interest represented by icons. However, by scaling the map larger the user loses the context. As a consequent the user might need to repeatedly zoom in and out to explore the map step by step.We present an approach that reduces the necessity of zooming by providing the user with the possibility of displacing the labels of a circular focus region. To that end, we utilize techniques from focus+context maps implementing the displacement of the labels by fish-eye projections. The visual association between labels and their point features is established by connecting lines aggregated to bundles. Our approach particularly guarantees that labels move smoothly when the user continuously shifts the focus region, which reduces distracting flickering effects while exploring the map by panning the map view. Further, when the user stops moving the focus region, mathematical programming is applied to optimize positions of the displaced labels. In an evaluation on real-world data and synthetically generated data, we show that our approach substantially increases the legibility of both the focus region and the displaced labels.

ABSTRACTIn the absence of street names or recognizable addresses, paired with rampant unplanned development and a lack of municipal initiative, Beirut defies traditional readings and can be described as unmappable. This paper documents an attempt to synthesize my ongoing artistic practice and my academic research into the representation of the contemporary city. It incorporates Guattari’s machinic, Debord’s psychogeography, and Rauschenberg’s neo-Dada approach to objects, all seen through the lens of Landscape Urbanism, an emerging field of study which places ‘the emphasis on urban processes … to construct a dialectical understanding of how [spatial form] relates to the processes that flow through, manifest, and sustain it’ (Corner, 2006. Terra fluxus. In C. Waldheim (Ed.), The landscape urbanism reader (pp. 21–33). New York: Princeton Architectural Press. p. 28). Conventional methods of looking at the city rely on static components and techniques, rendering them ‘inflexible in relation to the rapidly transforming conditions of contemporary urban culture’ (Waldheim, 2006. Landscape as urbanism. In C. Waldheim (Ed.), The landscape urbanism reader (pp. 35–53). New York: Princeton Architectural Press, p. 37). By incorporating traditionally unmappable forces, a machinic analysis of the city results in a more responsive, process-based framework that helps to dissociate systems from traditional formal and programmatic qualities. The subsequent mappings do not present the recognizable urban forms or landmarks usually associated with Beirut; my maps are not about way-finding. Instead, they are anecdotal diagrams, abstract schematics, and stylized image/objects that are intended as creative visualizations of subjective experiences and cultural practices in contemporary Beirut. They aspire to be insistently provocative to the urban way that ‘transforms the city … into an autocritical artifact’ (Vidler, 1992. The architectural uncanny: Essays in the modern unhomely. Cambridge: MIT Press, p. 210).

Every two years the International Cartographic Association (ICA) holds its international conference for Cartography and GI Science. The conference brings-together colleagues undertaking research, d...

ABSTRACTBuilding patterns are crucial structures and should be preserved in map generalization. However, while building patterns are not explicitly described in building datasets, map readers perceive building patterns effortlessly. Hence, to better support map generalization, it is important to automatically recognize building patterns in such datasets. This paper first proposes an extended and integrated typology of different building patterns. Based on the typology, building patterns are recognized using stroke and mesh. This method first structures the proximity graph of buildings, and then introduces six constraints (distance, size, shape, orientation, elongation, and facing ratio) to refine the original proximity graph. Strokes and meshes are derived from the refined proximity graph, and are used to recognize linear and grid building patterns, respectively. The proposed method is tested in four regions that are representative of different pattern types. The recognition results are evaluated in an expert survey and compared with the minimum spanning tree method. Assessment suggests that the linear and grid patterns in suburban and rural areas are recognized with satisfying results.

ABSTRACTThe omnipresence of orientation, wayfinding and navigation tasks in everyday life calls for high-quality cartographic media that help people to solve their tasks in the best possible way. Modern maps should not only consider modern visualization techniques and design approaches but also knowledge on the map user’s cognitive processing. Previous studies of cognitive cartography and spatial cognition identified grids as suitable cartographic elements that can enhance the accuracy of cognitive representations of geographic space. Grid lines form grid cells and these cells subdivide a map layout into different regions. These regions seem to contribute to a categorization of cartographically represented contents. The categorical organization of a map provides a superordinate spatial structure that can improve the recall of object locations. An important parameter influencing categorization is the distance between grid lines (spacing/separation). A previous study suggested 5 cm (paper distance) spacing as being suitable for an accurate performance in recalling object locations in topographic maps. Based on a recall-memory-paradigm adopted from experimental studies in cognitive psychology, the experiments reported in the present study take up this value and aim at specifying the ideal value of grid line spacing for object location memory. The results show that previous findings can be extended. The results allow the proposal of ideal grid line spacing in a 6.5-7.5 cm range. These spacing values help to reduce spatial distortion errors in the memory of object locations, especially in maps with a low amount of visual details.

ABSTRACTThe traditional way to calculate the global distortion of a given area in a map projection is to create what we call a local distortion criterion that is a function of the infinitesimal semi-axes of the Tissot's indicatrix. Some contemporary scholars criticize this method, saying that the map readers face distortion of the finite type. These researchers suggest taking plenty of simple random spherical elements (line sections, triangles) and average the distortion on them. Although the aforementioned researchers all state that their approach is something fundamentally different from the traditional method, the major disadvantage is that this method is irreproducible. Therefore, it has to be investigated whether the difference is really significant between these methods and if it is, what its nature is. At first, different distortion values are evaluated on a huge number of various projections showing the whole Earth. Correlation analysis shows that there exists a strong linear dependence between the corresponding infinitesimal and finite measures. A considerable difference can be observed if the examined area is not the whole globe rather a part of it. After optimizing a projection for different distortion measures, the isolines of equal distortion follow the boundary lines significantly closer using the traditional approach.