Mapping Where the Data is Not

Brendan Farrell from Clockwork Micro brings us 'Mapping Where the Data is Not'.
We present a solution to the problem of displaying the areas in a web map where no data (polygon data) is available. This problem comes up, for example, if polygons designate flood risk areas. One then wants to avoid interpreting an area that has not been mapped at all for flood risk as an area that has been mapped and found to have no flood risk. We present a solution using vector tiles and postgis.