Tuesday, April 09, 2019

The Map Context Frame for Navigation

The Map Context Frame is an interesting prototype "to support (interactive) map navigation by placing contextual information around a (interactive) map". When using interactive maps users often zoom in and out on the map to determine their location. For example users might zoom out on a map to confirm their relative position in terms of nearby towns, cities and other well known landmarks. The Map Context Frame is an aide to navigation which is designed to provide contextual spatial cues in the map frame so that users don't need to zoom in and out to determine their location.

The Map Context Frame provides a number of contextual spatial cues around the edge of the map showing the direction and distance to locations outside of the current map view. The spatial cues shown are different at different zoom levels. When zoomed out to a level which shows country labels on the map the spatial cues in the context frame will point towards countries outside the current map bounds. When you zoom in on the map the context cues will change from pointing towards other countries to instead show towns and cities outside the current map bounds.

You can read more about the purpose of the Map Context Frame and its methodology on its GitHub page and in the research paper A Context Frame for Interactive Maps (PDF).

The Map Context Frame system obviously must involve some kind of ranking to decide which location are the most important and therefore should be shown in the context frame. One factor in this ranking algorithm could be distance. If I'm searching around within a U.S. state at a zoom level which shows a few towns on the map then the context frame could show me the nearby towns & cities not in the current map view. Another factor in a ranking algorithm could be population size. Again if I'm searching within a state the context frame could show me nearby towns not in the current map view but also some of the biggest cities and the state capital (even if they are further away).

The demo map doesn't show local points of interest. This is probably because this is where it gets more difficult. If you are zoomed right in on a location in the demo map the context frame still shows you towns and cities. Whereas at this level of zoom nearby neighborhoods would probably be a greater aide to navigation. As would nearby points of interest, such as stations, museums and other well know local landmarks.

An alternative to using a Map Context Frame with an algorithm determining the context locations is to create a map with predetermined context locations. For example if you have a map on your website showing the location of your office then you might want to determine for yourself which locations to show in the context frame. For example you might want the context frame to point towards and show the distance to nearby stations, bus-stops and cafes. If that is the case then you might like Leaflet EdgeMarker.

Leaflet EdgeMarker is a plugin for the Leaflet map library which creates a map context frame with arrows pointing to predetermined locations outside of the current view. If you use Leaflet EdgeMarker you need to determine for yourself the locations which the arrows in the context frame will point to. Here is a demo of the Leaflet EdgeMarker in action.

No comments: