> From: Lennard [mailto:[email protected]] > Sent: Monday, January 30, 2012 12:33 PM > To: [email protected] > Subject: Re: [OSM-dev] Coastline shapefiles > > On 30-1-2012 6:09, Paul Norman wrote: > > I have been experimenting with generating the coastline shapefiles > > locally using > > http://svn.openstreetmap.org/applications/utils/coastcheck/ and ended > > up with a few questions > > > > 1. Is this the same code that is currently used to generate the > > processed_p files? > > Yes, except for the slight tweaking of some initial values. Also, two > sets of shapefiles are generated, each with slightly different values > for shape overlap. The first is processed_p, the second is another > shapefile from which shoreline_300 is generated. The latter one takes > more time to generate and then simplify.
How are the shoreline_300 generated? Coastcheck doesn't have any documentation, I had to figure out what doit did and how to compile the programs. > > > 2. It took my server about one hour from the start of extracting the > > coastline data to creating the shapefiles. My understanding was that > > this process took about a day. I'm using a different route to extract > > coastline data than osm2coast, could this account for the difference? > > A full coastline shapefile run (ie. both processed_p and shoreline_300) > takes a few hours to generate, generally. I have no doubt that current > hardware (cpu, ssd) can have a drastic positive influence to get it to > your 'one hour'. I'm querying my pgsnapshot database - I think this accounts for most of the differences. My server runs an AMD Phenom II 1090T x6 with 6 7200 RPM drives in RAID10 > > > 3. If I were to run the coastline generation daily and upload the > > files somewhere, could someone then host a slippymap showing coastline > errors? > > I'm sure there could be ways to get that done. If anyone is interested in doing something with these files, I can set up a cron script that will run the generation and scp it somewhere. > > > 4. Given that it only took an hour to generate, is there any way to > > get more frequent updates to the coastline files? > > Another limiting factor in this is that you would need the full planet > file, to be able to extract the coastlines. Applying diffs to update > that planet file adds a serious amount of time to a coastline run. Since I keep a pgsnapshot database up to date, this isn't an issue for my setup. _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
