On Thu, Mar 27, 2008 at 1:18 AM, Martijn van Oosterhout <[EMAIL PROTECTED]> wrote: > > On Wed, Mar 26, 2008 at 5:34 PM, Xin <[EMAIL PROTECTED]> wrote: > > I need to update the styling soon, so have to go through this whole process > > again. Is there anything I can do to speed up this process and reduce the > > footprint? Perhaps by generate only 1 tile for the million of empty tiles. > > Sure, use TileCache to only render tiles when someone actually wants > to look at them. On the NL tileserver we have half a dozen layers all > generated on the fly. For layers which are used a lot it uses a lot of > space, for layers not used much there's less diskspace... >
I was in the same boat and was having some troubles with TileCache on my system and didn't quite have the time to figure out why, so I threw something similar together. TileCache is undoubtedly better, but if that isn't going to fly for whatever reason here's an alternative. Requests are made to the url: http://your.domain.name/path/to/get_tile.py/handler?layer=layer1&z=[z]&x=[x]&y=[y] With z x y as the z x y according to Google's tile scheme (you might need to amend that as need be). Projection is in the Google / Virtual Earth projection. This was running on an apache system using mod_python. ----------------------------------------------------------------- import os, pg, datetime, sys from mapnik import * from mod_python import apache ## Renders tiles on request.. URL should be something along the lines of: ## http://your.domain.name/path/to/get_tile.py/handler?layer=layer1&z=[z]&x=[x]&y=[y] def render_tile(req, tile_root, layer, zoom_level, x_i, y_i, write_over=False): m = Map(256,256,"+proj=latlong +ellps=WGS84") # Actually in the '900913' projection, but this works.. may have something to do with # proj.4 not being supported on FreeBSD? if layer == 'layer1': layer1_lyr = Layer('layer1') layer1_lyr.datasource = Shapefile(file='/usr/path/to/shp') layer1_lyr_style = Style() layer1_lyr_rule = Rule() layer1_lyr_rule.symbols.append(LineSymbolizer(Color('black'), .02)) layer1_lyr_style.rules.append(layer1_lyr_rule) m.append_style('layer1', layer1_lyr_style) layer1_lyr.styles.append('layer1') m.layers.append(layer1_lyr) m.background = Color('transparent') m.zoom_to_box(layer1_lyr.envelope()) elif layer == 'layer2': #symbology rules for layer2 rules for layer two... else: sys.exit(2) tile_size = 256 # figure out how many tiles per row/column we'll have tiles_per_row = pow(2, zoom_level); tile_coord_size = 40075016.6855784 / tiles_per_row #size in coordinates of each tile # For the bounding boxes.. based on the google tile scheme tile_x_min = int(x_i) * tile_coord_size tile_y_min = (tiles_per_row - 1 - int(y_i)) * tile_coord_size tile_x_max = tile_x_min + tile_coord_size tile_y_max = tile_y_min + tile_coord_size render_tile_to_file(req, m, tile_root, zoom_level, int(x_i), int(y_i), \ tile_x_min, tile_y_min, tile_x_max, tile_y_max, \ True) ## This function renders individual tiles to the tile directory def render_tile_to_file(req, render_map, tile_root, z, x, y, LL_x, LL_y, UR_x, UR_y, write_over): if not tile_root.endswith('/'): tile_root += '/' if not os.path.exists(tile_root[0:len(tile_root)-1]): raise RenderError, "'" + tile_root + "' path does not exist or you do not have proper missions." exit if not os.path.exists(tile_root + 'z' + str(z) + '/'): os.mkdir(tile_root + 'z' + str(z) + '/') if not os.path.exists(tile_root+ 'z' + str(z) + '/' + 'x' + str(x) + '/'): os.mkdir(tile_root + 'z' + str(z) + '/' + 'x' + str(x) + '/') if os.path.isfile(tile_root + 'z' + str(z) + '/x' + str(x) + '/y' + str(y) + '.png') \ and not write_over: raise RenderError, tile_root + 'z' + str(z) + '/x' + str(x) + '/y' + str(y) + '.png' + ' exists' + \ ' already, file not written over.' exit render_map.zoom_to_box(Envelope(LL_x, LL_y, UR_x, UR_y)) img_path = tile_root + 'z' + str(z) + '/x' + str(x) + '/y' + str(y) + '.png' render_to_file(render_map,img_path, 'png') def handler(req, layer, z, x, y): req.content_type = "image/png" # translate URL to system path filepath = '/usr/local/www/apache22/data/tiles/' + str(layer) + '/z' + str(z) + '/x' + str(x) + '/y' + str(y) + '.png' # if tile doesn't already exist, render it.. if not os.path.isfile(filepath): render_tile(req, '/usr/local/www/apache22/data/tiles/' + str(layer) + '/', layer, z, x, y) req.sendfile(filepath) return apache.OK ----------------------------------------------------------------- Cheers, Andy _______________________________________________ Mapnik-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/mapnik-users
