buttman kirjoitti: >>>> ls.srs.name > 'WGS 84' >>>> srs.units > (0.017453292519943282, 'degree') >>>> ls.length > 0.88329271346608429 > > So how do I go from degrees to miles? According to the docs, Distance > does not handle 'degrees' as a unit. Should I somehow convert to > another srs before I calculate distance? Or is there a better way?
You can calculate approximate distances by using decimal degrees, but it requires a bit of more work and are not straightforward to calculate. (due the fact that length of degree varies depending on where your measured points are located at!) You might find this page a bit helpful: http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.htm > On Oct 12, 2:53 am, Jani Tiainen <rede...@gmail.com> wrote: >> HARRY POTTRER kirjoitti: >> >> >> >>> I have a model which represents a route. I can use the `make_line()` >>> geoqueryset method to create a LineString like so: >>>>>> r = Route.objects.get(pk=33) >>>>>> # a route from Seattle to New York to Miami, a total distance >>>>>> # of about 3043.8 nautical miles >>>>>> r >>> <Route: KSEA-KLGA-KMIA> >>>>>> # a collection of the airports used in the route >>>>>> # turned into a LineString >>>>>> ls = Airport.objects.filter(routebase__route=r).make_line() >>>>>> ls >>> <LineString object at 0x2cd42e0> >>> How can I find the total distance of that LineString object, so that >>> it returns a Distance object that I can then convert to nautical >>> miles? the .length() method here just returns a float, which is in who- >>> knows-what units... >> It's exactly in the units that are specified in your SRS definition. To >> go beyond that you can use Distance to make math and conversions to >> another units.. >> >> Note that "length" gives linear distance, not spherical so in long >> distances you get a distorted length. >> >> -- >> Jani Tiainen > > -- Jani Tiainen --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
