Flow MapsKazimierz J Zaniewski, University of Wisconsin-OshkoshFlow maps are considered the best ways of showing interaction between two or more places. However, there are at least two major issues related to the design and production of these maps. The amount of information that can be shown on some types of flow maps is limited, and a very few software programs have the capabilities of generating such maps. The first shortcoming can be addressed by certain types of proportional symbol maps, the second by having access to three less known (and relatively cheap or free) mapping packages. This paper presents a series of flow maps showing various types of spatial interaction (airline traffic, inter-state migrations, and road traffic) and alternative ways of displaying similar information.
https://speakerdeck.com/nvkelso/flow-mapsAutomatic Flow Map Creation Using a Force-Directed LayoutDaniel Stephen, Oregon State UniversityBernard Jenny, Oregon State University Ritesh Sharma, Oregon State UniversityEugene Zhang, Oregon State UniversityIan Muehlenhaus, James Madison UniversityCreating attractive and easy to read origin-destination flow maps is a time-consuming process, because there are no automatic methods that apply the variety of cartographic principles needed for an effective flow map layout. We present an algorithmic method for quickly creating flow maps that is able to apply several of the most important cartographic principles. Starting with flows drawn as Bézier curves between pairs of nodes, the shapes of the flows are adjusted using a force-directed layout method, where each flow exerts repelling forces on neighboring flows. The forces are tuned to improve readability through a reduction of overlap between flows and to prevent flows from passing through unrelated nodes, while maintaining the smooth shape of the Bézier curves. This method creates flow maps with reduced overlap between flows and nodes in a short time.
Mapping and Analyzing Space-time Data: The Zebra Mussel InvasionAileen Buckley, ESRIDreissena polymorpha, commonly known as the zebra mussel, has earned a well-deserved reputation as an international dilemma and a national threat. This paper explores the invasive nature of this extremely detrimental species through visual and analytical analysis of its related space-time data. I used ArcGIS to visually explore the spread of zebra mussels. Then I performed spatial analysis to analyze patterns of spread over time. Standard deviational ellipses and mean center points gave clues to the extent and direction of spread. Grouping analysis helped determine in which years the patterns of spread were similar. Hex mapping and density mapping provided insights into hot spots with concentrations of sightings. With a more complete understanding of this devastating invasive species, I created story maps to educate the public about the havoc these mussels can wreak and how people can help to stop the invasion by taking precautionary measures.
Trivariate Climatological Mapping of Historical Sea Ice (10 minute talk)
Mark Denil, US National Ice CenterFor several years the question of how to map historical sea ice conditions has been nagging planners, navigators, and scientists. In 2015 the US National Ice Center (NIC) introduced a new set of data and map products to address the understandable envisioning of sea ice conditions over a given range of dates (say, the first 15 days of May 2015), and, optionally, through a given depth of time (the first 15 days of May 2007 through 2015). This talk will describe how the trivariate climo data sets are constructed from publicly available NIC Daily sea ice analysis data sets, and the development of the standard map products for the Arctic and Antarctic.
