Ubuntu Manpage: tilecache - Cache and serve map tiles

NAME

       tilecache - Cache and serve map tiles

DESCRIPTION

       TileCache is a BSD licensed tile caching mechanism.  The goal is to make it easy to set up
       a WMS or TMS frontend to any backend data services you might be  interested  in,  using  a
       pluggable caching and rendering mechanism.

       TileCache was developed by MetaCarta Labs and released to the public under a BSD license.

       The  TileCache  was  designed  as  a companion to OpenLayers, the BSD licensed web mapping
       interface. If you are using TileCache with OpenLayers, please read  the  section  of  this
       readme which describes how to do so. For additional help with setting up TileCache for use
       with OpenLayers, please feel free to stop by #openlayers, on irc.freenode.net, or to  send
       email to tilecache@openlayers.org.

RUNNING UNDER CGI

       • TileCache  should  have  a  cgi  installed under /usr/lib/cgi-bin, called tilecache.cgi.
         This is accessible from http://yourmachine.example.com/cgi-bin/tilecache.cgi.

       • Edit /etc/tilecache.cfg to point the DiskCache to the location you wish to cache  tiles,
         and the layers to point to the map file or WMS server you wish to cache.

       • Visit:

         http://yourmachine.example.com/cgi-bin/tilecache.cgi?LAYERS=basic&SERVICE=WMS&BBOX=-180,-90,0,90

       • Or visit:

         http://yourmachine.example.com/cgi-bin/tilecache.cgi/1.0.0/basic/0/0/0.png

       • If you see a tile, TileCache is working correctly.

RUNNING UNDER MOD_PYTHON

       • Edit  /etc/tilecache.cfg to point the DiskCache to the location you wish to cache tiles,
         and the layers to point to the map file or WMS server you wish to cache.

       • Add the following to your Apache configuration:

         Alias /tiles /var/lib/python-support/python2.4/tilecache/
         <Directory /var/lib/python-support/python2.4/>
              SetHandler python-program
              PythonHandler TileCache.Service
              PythonOption TileCacheConfig /etc/tilecache.cfg
         </Directory>

       • Visit one of the URLs described above, replacing tilecache.cgi with tilecache.py

       • If you see a tile you have set up your configuration correctly. Congrats!

RUNNING STANDALONE (UNDER WSGI)

       TileCache includes standalone HTTP server which uses the WSGI handler. This implementation
       depends on Python Paste , which can be installed via the python-paste package.

       For versions of Python earlier than 2.5, you will also need to install wsgiref:

       http://cheeseshop.python.org/pypi/wsgiref

       Once you have all the prerequisites installed, simply run:

       /usr/sbin/tilecache_http_server

       This will start a webserver listening on port 8080 (by default), after which you should be
       able to open:

       http://yourmachine.example.com:8080/1.0.0/basic/0/0/0.png

       to see your first tile.

RUNNING UNDER FASTCGI

       TileCache includes a fastcgi implementation. In order to use this implementation, you will
       need to install flup, available from:

       http://trac.saddi.com/flup

       This  implementation also depends on Python Paste, which can be downloaded via the python-
       paste package:

       Once you have done this, you can configure your fastcgi server to use tilecache.fcgi.

       Configuring FastCGI is beyond the scope of this documentation.

CONFIGURATION

TileCache is configured by a config file, defaulting to tilecache.cfg. There are several
parameters to control TileCache layers that are applicable to all layers:

bbox The bounding box of the Layer. The resolutions array defaults to having resolutions
which are equal to the bbox divided by 512 (two standard tiles).

debug Whether to send debug output to the error.log. Defaults to "yes", can be set to
"no"

description
Layer description, used in some metadata responses. Default is blank.

extension
File extension of the layer. Used to request images from WMS servers, as well as
when writing cache files.

layers A string used to describe the layers. Typically passed directly to the renderer.
The WMSLayer sends this in the HTTP request, and the MapServerLayer chooses which
layer to render based on this string. If no layer is provided, the layer name is
used to fill this property.

levels An integer, describing the number of ´zoom levels´ or scales to support. Overridden
by resolutions, if passed.

mapfile
The absolute file location of a mapfile. Required for MapServer and Mapnik layers.

maxResolution
The maximum resolution. If this is set, a resolutions array is automatically
calculated up to a number of levels controlled by the ´levels´ option.

metaTile
set to "yes" to turn on metaTiling. This will request larger tiles, and split them
up using the Python Imaging library. Defaults to "no".

metaBuffer
an integer number of pixels to request around the outside of the rendered tile.
This is good to combat edge effects in various map renderers. Defaults to 10.

metaSize
A comma separated pair of integers, which is used to determine how many tiles
should be rendered when using metaTiling. Default is 5,5.

resolutions
Comma separate list of resolutions you want the TileCache instance to support.

size Comma separated set of integers, describing the width/height of the tiles. Defaults
to 256,256

srs String describing the SRS value. Default is "EPSG:4326"

type The type of layer. Options are: WMSLayer, MapnikLayer, MapServerLayer, ImageLayer

url URL to use when requesting images from a remote WMS server. Required for WMSLayer.

watermarkImage
The watermarkImage parameter is assigned on a per-layer basis. This is a fully
qualified path to an image you would like to apply to each tile. We recommend you
use a watermark image the same size as your tiles. If using the default tile size,
you should use a 256x256 image. NOTE: Python Imaging Library DOES NOT support
interlaced images.

watermarkOpacity
The watermarkOpacity parameter is assigned on a per-layer basis. This configures
the opacity of the watermark over the tile, it is a floating point number between 0
and 1. Usage is optional and will otherwise default.

extent_type
Setting this to ´loose´ will allow TileCache to generate tiles outside the maximum
bounding box. Useful for clients that don´t know when to stop asking for tiles.

tms_type
Setting this to "google" will cause tiles to switch vertical order (that is,
following the Google style x/y pattern).

USING TILECACHE WITH OPENLAYERS

       To  run  OpenLayers  with TileCache the URL passed to the OpenLayers.Layer.WMS constructor
       must point to the TileCache script, i.e. tilecache.cgi or tilecache.py. As an example  see
       the    example-cgi.html    file    included   in   the   TileCache   distribution,   under
       /usr/share/doc/tilecache/examples/.

       Note: example-cgi.html assumes TileCache is set up under CGI (see above). If  you  set  up
       TileCache  under  mod_python you´d need to slighly modify example-cgi.html: the URL passed
       to the OpenLayers.Layer.WMS constructor must point to the mod_python script as opposed  to
       the  CGI  script.  Similarly, you would need to edit this URL if you were to use TileCache
       with the standalone HTTP Server or FastCGI.

       The most important thing to do is to  ensure  that  the  OpenLayers  Layer  has  the  same
       resolutions  and  bounding  box as your TileCache layer. You can define the resolutions in
       OpenLayers via the ´resolutions´ option or the ´maxResolution´ option on  the  layer.  The
       maxExtent should be defined to match the bbox parameter of the TileCache layer.

USING TILECACHE WITH MAPSERVER

       MapServer  has  a  map  level  metadata  option,  labelcache_map_edge_buffer, which is set
       automatically by TileCache to the metaBuffer plus five when metaTiling is on, if it is not
       set in the mapfile.

       If you are using MetaTiling, be aware that MapServer generates interlaced PNG files, which
       PIL will not  read.  See  http://mapserver.gis.umn.edu/docs/faq/pil_mapscript  on  how  to
       resolve this.

SEEDING YOUR TILECACHE

       The tilecache_seed utility will seed tiles in a cache automatically. You will need to have
       TileCache set up in one of the previously described configurations.

   Usage
       /usr/sbin/tilecache_seed <url> <layer> [<zoom start> <zoom stop> [<bbox>]]

   Arguments
       url    http://example.com/yourdir/tilecache.cgi?                                        or
              http://example.com/yourdir/tilecache.py

       layer  same layer name that is in the tilecache.cfg

       zoom start
              Zoom level to start the process

       zoom end
              Zoom level to end the process

       bbox   The bounding box to seed

   Seeding by center point and radius
       If  called  without  zoom  level arguments, tilecache_seed.py will assume that it needs to
       read a list of points and radii from standard input, in the form:

       <lat>,<lon>,<radius>
       <lat>,<lon>,<radius>
       <lat>,<lon>,<radius>
       <lat>,<lon>,<radius>
       <ctrl + d>

       The format of this file is:

       lon    the position(s) to seed longitude

       lat    the position(s) to seed latitude

       radius the radius around the lon/lat to seed in degrees

   Examples
       An example with zoom levels 5 through 12 would be like;

       $ /usr/sbin/tilecache_seed "http://example.com/yourdir/tilecache.cgi?" Zip_Codes 5 12 "-118.12500,31.952162238,-116.015625,34.3071438563"

       The bbox can be dropped and defaults to world lonlat(-180,-90,180,90):

       $ /usr/sbin/tilecache_seed.py "http://example.com/yourdir/tilecache.cgi?" Zip_Codes 0 9

       In  center  point/radius  mode,  the  zoom  level  range  is  not  specifiable  from   the
       command-line. An example usage might look like:

       $ /usr/sbin/tilecache_seed.py "http://example.com/yourdir/tilecache.cgi?" Zip_Codes
       -118.12500,31.952162238,0.05
       -121.46327,32.345345645,0.08
       <Ctrl+D>

       ... the seeding will then commence ...

CLEANING YOUR TILECACHE

       The  tilecache_clean  utility  will remove the least recently accessed tiles from a cache,
       down to a specified size.

   Usage
       /usr/sbin/tilecache_clean [options] <cache_location>

   Options
       --version
              show program´s version number and exit

       -h , --help
              show this help message and exit

       -s SIZE, --size SIZE
              Maximum cache size, in megabytes.

       -e ENTRIES, --entries ENTRIES
              Maximum cache entries. This limits the amount of memory that will be used to  store
              information about tiles to remove.

   Notes
       The  --entries  option to tilecache_clean.py is optional, and is used to regulate how much
       memory it uses to do its bookkeeping. The default value of 1 million will  hopefully  keep
       RAM  utilization  under  about  100M  on a 32-bit x86 Linux machine. If tilecache_clean.py
       doesn´t appear to be keeping your disk cache down to an appropriate size, try upping  this
       value.

       tilecache_clean is designed to be run from a cronjob like so:

       00 05 * * *  /usr/sbin/tilecache_clean.py -s500 /var/www/tilecache

TROUBLESHOOTING

       Occasionally,  for  some  reason, when using meta tiles, your server may leave behind lock
       files. If this happens, there will be files in your cache  directory  with  the  extension
       ´.lck´.  If you are seeing tiles not render and taking multiple minutes before returning a
       500 error, you may be suffering under a stuck lock.

       Removing all files with extension ´.lck´  from  the  cache  directory  will  resolve  this
       problem.

AUTHOR

       crschmidt@metacarta.com

COPYRIGHT

       (c) 2006-2007 MetaCarta, Inc.  Distributed under the BSD license.