Thank you Dane. I ended up just creating all the layer definitions by hand, one for each state directory, and set them to reference a single layer style. Not elegant, but it works fine. Thanks for the tip. Mark
On Jul 7, 2011, at 2:44 PM, Dane Springmeyer wrote: > On Jul 7, 2011, at 2:16 PM, Mark Vahrenwald wrote: > >> Hi all, >> I'm in the process of building a Mapnik tile cache from a dataset of >> shapefiles. The file path to my datasources is hard-coded, and the data >> itself is broken down in separate folders by state with the state >> abbreviation as part of the file name (an example file path: >> "../shapefiles/US/CA/CArivers.shp"). The result of this is that I can >> render individual states, but I'm not able to render multiple states >> together because the datasource only allows me to point to one state >> directory at at time. >> Given that this is a standard method of file structure for TomTom/Navteq >> datasets, I'm assuming there's a work-around out there, but I haven't come >> across it yet. Thanks in advance for any suggestions. >> Mark > > Mark, > > Generally if you have more than one shapefile you want to show, then you > would create another layer definition for that datasource. As mapnik supports > named styles you would then be able to create one style and apply that style > to all the layers needed. > > If the # of individual shapefiles is enough that creating all those layers > one by one is overly tedius, then perhaps you could just write a simple > script to loop through each directory and author the chunk of Mapnik XML > needed to declare each as a layer. > > Generally hundreds of layers in an XML is still quite fast (after the initial > XML load is finished) because each layer's individual bounding box will be > cached by mapnik and when rendering only those layers that intersect with a > tile's extent will be queried. 1000's of layers would also likely work fine > rendering if you could script the creation of the map document. > > Now, if you are using some other tool, like TileMill to author your > stylesheets, then scripting Mapnik XML is not as straighforward (though in > the case of TileMill you could script the creation of the mml file which is > just a JSON version of Mapnik's XML). In this case you might be better off > scripting the union of a group of shapefiles that all have the same schema > into one or several larger shapefiles. I would use ogr's --append function > for this task, but ogr's VRT support could also come in quite handy: > http://www.gdal.org/ogr/drv_vrt.html > > Does that help? > > Dane _______________________________________________ Mapnik-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/mapnik-users
