Thanks for the replies. I think i'll try bratliff's suggestion - and hope that the exact same coords have been used for neighbouring districts. (A quick look at the coords suggests that adjacent borders have the same coords so hopefully this method will succeed).
Martin. On 3 Sep, 13:54, bratliff <[email protected]> wrote: > On Sep 3, 8:00 am, Martin <[email protected]> wrote: > > > > > Hi. > > > I need to add a simple polyline to a map which represents the Polish > > border. > > > After much research i have a shapefile which contains all districts in > > Poland and each district is represented by a polygon. > > > So my question is - is there a simple method to extract the coords of > > the outer edge of the polygons so i can make my polyline? > > > I've converted the shapefile to KML with shp2kml thinking i could edit > > the KML but it contains so many coords i just don't fancy doing it > > manually. > > > I found an online shapefile editor here:http://www.mapshaper.org/ > > > But the interface is slow and clumsy and it'd probably take me all day > > to edit the shapefile. > > > Of course i've searched for a shapefile (or whatever format) that > > contains just the country border i require but found none - only > > finding the same district polygons that i already have. > > > Has anyone got any experience of this? > > > Thanks. > > > Martin. > > If your polys are a perfect fit like the U.S. Census Department > Cartographic boundary files, just count the number of occurrances of > each Lat/Lon point pair. First you have to strip out duplicates in > the same poly. The first & last should always be duplicates. Some > polys contain other redundant pairs which will always be adjacent to > each other in the poly. With each poly containing only unique points, > count the number of times a point appears in all polys. If it > apprears once, it is on the border of all of your polys. If it > appears twice, it is on the border between two of your polys. > > For what it is worth, I am developing a "light weight" poly facility > for V3. It can handle multiple polys efficiently because polys are > grouped in clusters rather than in individual OverlayViews. A single > CANVAS element contains every poly in the same tile space. It makes > union / intersection / XOR / etc operations feasible. > > Look at: > > www.polyarc.us/polycluster > > for some demos. It does not work in Internet Explorer but every other > popular browser is supported. > > You could keep your polys discrete. You could fake a large poly with > small polys by suppressing the stroke. You could also combine polys > into regional groups. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google Maps API" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/Google-Maps-API?hl=en -~----------~----~----~----~------~----~------~--~---
