During the reproduction of historical isochrones created with the API of ORS - openrouteservice.org, I ran into issues with the resolution. About 3 years ago, the returned isochrones had higher resolution than today and there is no option to manipulate any kind of resolution-parameter (as far as I know).
ORS historical (3 years ago): higher resolution
ORS today: lower resolution
library(leaflet)
library(openrouteservice)
coords <- c(9.4619375, 47.4776429)
isochrone_ors <- ors_isochrones(coords, range = 11*60)
leaflet() %>%
addProviderTiles(providers$Stamen.TonerLite, group = "Toner Lite") %>%
addGeoJSON(geojson = isochrone_ors) %>%
fitBBox(isochrone_ors$bbox)
OSRM: today
I tried to reproduce the isochrones using osrm::osrmIsochrone(). Unfortunately this osrm implementation generates sqare-cut and partwise disjunct isochrones for quite low resolutions - which is far from the historical ORS-isochrones.
Attention: The server in use http://router.project-osrm.org/ is not very stable
options(osrm.server = "http://router.project-osrm.org/", osrm.profile = "driving")
isochrone_osrm <- osrm::osrmIsochrone(loc = coords, breaks = c(0,11), res = 150)
leaflet() %>%
addProviderTiles(providers$Stamen.TonerLite, group = "Toner Lite") %>%
addPolygons(data = isochrone_osrm)
Do any of you have an idea on how to reproduce the historical isochrones in a better way? Are there more suitable packages or API's?