Mapping with Kepler (kepler.gl)
What Kepler does
Kepler.gl is a web-based mapping tool that lets us input and integrate coordinates on a world map developed by Uber. The genius of kepler.gl lies in the quantity of data that it can process. It is one thing to plot out all of the Olympics Games since 1896 in yellow dots. It is another to connect each yellow dot to the national capitals that sent delegations to it. The visualization becomes richer when contributing capitals’ are marked in colors aside from yellow, and when they vary in size on the map depending on how many athletes countries’ sent. The lines become easier to parse when we add a time filter that allows us to isolate specific Games or set of Games, and so compare the rush of African delegations to the Games in the 1960s to the entry of Asian states a decade earlier.
How to use Kepler
Initiate a kepler.gl map by uploading a simple data file that charts latitudinal and longitudinal data in CSV or GeoJson formats. Having done so, you will see dots appear in the specified locations, and by brushing over these, will see all of the metadata that accompanied the coordinates on the uploaded data file. Next turn your attention to the four icons that appear beneath the kepler.gl logo on the left side of the screen.
The first of these, “Layers,” determines what data the map will draw upon (see the “Add Data”), and which of the twelve visualizations the data will take. Beneath each of the twelve are tools for determining size and color of marks, whether points or “hexbins.” For several (e.g. grid, cluster), density of events comes at the cost of brush-over metadata, revealing tallies of the points contained in the selected grid or cluster. Other visualizations let you draw associations between points. Thus, an arc or line (see the map below) or full-fledged “trip” can mark multiple points on any progression, provided the user enters latitude and longitude fields beneath whichever of these visualizations was selected.
The second icon, “Filters,” allows us to isolate specific strings, or metadata, to highlight on the maps. In the case of the Olympics, we might show only the events that occurred in the 1950s, or that attracted more than 100 national delegations. Granted, Kepler does not appear to accept algorithms to filter data within a given string–for example, to find cities that attracted 100+ delegations). But it does let us enter the relevant sites manually (click “value”) . The third icon, “Interactions,” provides a tool similar to filtering, titled “Tooltip,” with which we determine which threads from our original data set we can show on the map. Another tool, “coordinator,” allows us to track latitude and longitude and place new points at desired coordinates. The final icon, “Base map,” determines essential settings like the color of the map, and the features it should include (roads, buildings, etc.).