The current pace of technological innovation in web mapping offers new opportunities and creates new challenges for web cartographers. The continual development of new technological solutions produces a fundamental tension: the more flexible and expansive web mapping options become, the more difficult it is to maintain fluency in the teaching and application of these technologies. We addressed this tension by completing a three-stage, empirical process for understanding how best to learn and implement contemporary web mapping technologies. To narrow our investigation, we focused upon education at the university level, rather than a professional production environment, and upon open-source client-side web mapping technologies, rather than complementary server-side or cloud-based technologies. The process comprised three studies: (1) a competitive analysis study of contemporary web mapping technologies, (2) a needs-assessment survey of web map designers/developers regarding past experiences with these technologies, and (3) a diary study charting the implementation of a subset of potentially viable technologies, as identified through the first two studies. The process successfully achieved the practical goal of identifying a candidate set of web mapping technologies for teaching web mapping, and also revealed broader insights into web map design and education generally as well as ways to cope with evolving web mapping technologies.

Spatial decisions increasingly are made by both professional and citizen stakeholders using interactive maps, yet few empirically-derived guidelines exist for designing interactive maps that support complex reasoning and decision making across problem contexts. We address this gap through an online map study with 122 participants with varying expertise. The study required participants to assume two hypothetical scenarios in the North American hazardous waste trade, review geographic information on environmental justice impacts using a different interactive map for each scenario, and arrive at an optimal decision outcome. This study followed a 2 × 2 factorial design, varying interface complexity (the number of supported interaction operators) and decision complexity (the number of decision criteria) as the independent variables and controlling for participant expertise with the hazardous waste trade and other aspects of cartographic design. Our findings indicate that interface complexity, not decision complexity, influenced decision outcomes, with participants arriving at better decisions using the simpler interface. However, expertise was a moderating effect, with experts and non-experts using different interaction strategies to arrive at their decisions. The research contributes to cartography, geovisualization, spatial decision science, urban planning, and visual analytics as well as to scholarship on environmental justice, the geography of hazardous waste, and participatory mapping.

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Problem: Interactive or "slippy" web maps have revolutionized cartography. Slippy maps present a single, coherentlydesigned reference map that can be panned to numerous geographic locations and zoomed across multiple scales. Further, they apply scale-dependent style rules to detailed geographic datasets, with the resulting designs rendered as a large set of interlocking tiles. To account for constraints in data bandwidth, processing, and storage, only those tiles relevant to the user's location and past interactions are served into the web browser or other application, resulting in a seamless, realtime user experience of "a map of everywhere". These slippy tilesets often are used as basemaps for advanced cartographic web and mobile applications, overlaying thematic information and other linework. Arguably, such slippy map mashups are the most common map seen and used today (and perhaps of all time). Yet, most of the cartographic design canon was developed long before slippy maps were possible. Do any of our time-tested design traditions in thematic cartography apply in today's interactive and multiscale mapping context? In this presentation, we discuss preliminary insights from an online map study about the design of interactive and multiscale thematic maps.Background: Our research integrates the cartographic tradition in thematic representation with growing research on interaction design. Thematic maps depict the distribution of one or several geographic phenomena, with the base reference information used as context for interpreting spatial variation in the thematic information [1]. Thematic maps grew in popularity in the 19 th century at the onset of the modern global economy as a method for tracking and controlling materials, labor, and goods [2], and, in today's information-driven society, are created by cartographers for reasons ranging from popular news reporting to exploratory scientific visualization. Thematic maps enable geographic imagination and spatial thinking, often representing abstract or statistical concepts that cannot be observed directly. Common thematic map types include choropleth, dot density, proportional symbol, and isoline, among others [3].Thematic maps can be organized in at least two ways. First, thematic map types differ in the visual variable used to encode the thematic information, or the basic graphic dimension separating variation in the thematic attribute of interest from other reference context [4]. For instance, choropleth maps typically employ the visual variables related to color (particularly color value, sometimes crossing multiple hues or saturations), dot density maps use a combination of arrangement and size, an emergent visual dimension sometimes described as "numerousness" [5], proportional symbol maps use size, and isoline maps use location (creating a new set of geographic linework based on thematic information), and also can include a color ramp between isolines similar to choropleth maps.Second, thematic maps differ in the visual metaphor they evoke in the relatio...

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