4 ms·
But measuring distance over the actually existing possible routes is much more accurate and honest. See these random examples: http://resources.esri.com/help/9.
by aw3c2 14y ago
But measuring distance over the actually existing possible routes is much more accurate and honest. See these random examples: http://resources.esri.com/help/9.3/arcgisdesktop/com/gp_toolref/geoprocessing/GPKAC_network_service_area.gif http://resources.esri.com/help/9.3/arcgisdesktop/com/gp_tool... and http://blog.lib.umn.edu/levin031/transportationist//WalkingMap.png http://blog.lib.umn.edu/levin031/transportationist//WalkingM...
Granted, this either needs more processing power server-side or a data model where the network (street, areas, etc) data is actually available on the client machine to calculate it.
edit: http://www.mysociety.org/2006/travel-time-maps/ http://www.mysociety.org/2006/travel-time-maps/ is a very nice detailed write-up about those maps.
- paulgb 14y agoIn both examples, concentric circles are a pretty good approximation. Considering that the 15-minute walk area will have high variability due to walking speed and traffic lights, detailed contours just give a false sense of accuracy. Like a bathroom scale that reports your weight to nine digits. Don't get me wrong, I love travel time maps in the right context. I actually made an interactive travel time map for transit in Toronto. It only works in Chrome but can be found here: http://ttcvis.s3-website-us-east-1.amazonaws.com/ http://ttcvis.s3-website-us-east-1.amazonaws.com/ Thanks for the link in the edit, I love write-ups of data visualizations and from a quick skim this looks really interesting.