Map Lenses

Esri has released a Maps Lens library which allows developers to add 'draggable map insets' to their maps.

Esri suggest the tool could be used for before and after maps, for example instead of the now fairly common swiping method to horizontally transition between two different maps of the same location. You can view an example of swiping between two maps on this visualization of Europe in 1914 and 2014.

Esri's new Maps Lens library instead allows you to add smaller draggable map insets on top of a base map layer. You can view a demo of the library in action on this Lens map and the source code for the demo is available here.


Some good examples of using a map lens to compare before and after maps are available in the Smithsonian & Esri History Maps collection/

The Smithsonian & ESRI History Maps are a series of maps combining historical maps from the David Rumsey collection with Esri's modern aerial imagery. Each of the maps includes a neat magnifying glass tool that allows you to view the modern day aerial image through the historical map. You can even switch the views around and compare the historical map on top of the modern aerial imagery.

The series includes historical maps of a number of US cities, including New York, San Francisco, Chicago, Washington DC, LA and Denver.