PostGIS Cookbook - Second Edition

How to do it...

The pgr_drivingdistance polygon we created is the first step in the demographic analysis. Refer to the Driving distance/service area calculation recipe if you need to familiarize yourself with its use. In this case, we'll consider the cycling distance. The nearest node to the Cleveland Metroparks Zoo is 24746, according to our loaded dataset; so we'll use that as the center point for our pgr_drivingdistance calculation and we'll use approximately 6 kilometers as our distance, as we want to know the number of zoo visitors within this distance of the Cleveland Metroparks Zoo. However, since our data is using 4326 EPSG, the distance we will give the function will be in degrees, so 0.05 will give us an approximate distance of ...