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The goal:

I am attempting to generate map tiles with EPSG:4326 instead of web mercator by specifying EPSG:4326 in the mapnik style file srs attributes


My current setup:

I am running Ubuntu 14.14 LTS and have followed the switch2osm.org manually-building-a-tile-server-14-04 instructions. Using the default projection, I was able to successfully import data and serve tiles to a client. I am using the stack of osm2pgsql, renderd, mapnik, mod_tile, apache, postgres, and the OSM Bright stylesheet.

To import I used:

osm2pgsql --slim -d gis -C 16000 --number-processes 3 mapdata.osm.pbf

Then to run renderd:

sudo -u mapnik renderd -f -c /usr/local/etc/renderd.conf

At this point, I had everything working to serve up web mercator.


What I have completed to attempt to serve tiles in EPSG:4326:

First I reimported the data with osm2pgsql using the -l flag:

osm2pgsql  -l --slim -d gis -C 16000 --number-processes 3 mapdata.osm.pbf

I then updated the mapnik stylesheet map and layer srs attributes to match what was defined in http://spatialreference.org/ref/epsg/4326/mapnik/

srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs"

When starting renderd I will then receive the error:

"Unknown projection string, using web mercator as never the less.
 +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs"

I also attempted a few other options:

srs="+init=epsg:4326"

srs="+proj=longlat +datum=WGS84 +no_defs"

After seeing a post recommending to check if proj-epsg package is installed, I was heading down the path that proj was missing on my system (https://github.com/mapnik/mapnik/wiki/InstallationTroubleshooting#proj_init_error)

Per this proj init error guide I reinstalled proj to no effect.

I confirmed I do have it:

~$ proj
Rel. 4.8.0, 6 March 2012
usage: proj [ -beEfiIlormsStTvVwW [args] ] [ +opts[=arg] ] [ files ]

I have checked my /usr/share/proj/epsg file and it contains an entry:

# WGS 84
<4326> +proj=longlat +datum=WGS84 +no_defs  <>

The guide shows a different path to /usr/local/share/proj/epsg. On my system it is /usr/share/proj/epsg


Question:

Is srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs" to output EPSG:4326 a valid option to generate tiles with renderd or is this not a possibility?


For reference, current configuration files:

renderd.conf:

[renderd]
socketname=/var/run/renderd/renderd.sock
num_threads=4
tile_dir=/var/lib/mod_tile
stats_file=/var/run/renderd/renderd.stats


[mapnik]
plugins_dir=/usr/local/lib/mapnik/input
font_dir=/usr/share/fonts/truetype/ttf-dejavu
font_dir_recurse=1

[default]
URI=/osm_tiles/
TILEDIR=/var/lib/mod_tile
XML=/usr/local/share/maps/style/OSMBright/OSMBright.xml
HOST=localhost
TILESIZE=256

problem snippet EPSG:4326 version of mapnik OSMBright.xml:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE Map[]>
<Map srs="+proj=longlat +datum=WGS84 +no_defs" 
font-directory="./fonts" background-color="#c4dff6"
maximum-extent="-20037508.34,-20037508.34,20037508.34,20037508.34">

working snippet web mercator version of mapnik OSMBright.xml:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE Map[]>
<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over" 
font-directory="./fonts" background-color="#c4dff6"
maximum-extent="-20037508.34,-20037508.34,20037508.34,20037508.34">

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