Few pointers to get you started. You've already done some research, so you know the right places to look for more info:
Don't use a Markers layer. Do use a Vector layer.
Vector layer can be styled. Each of your points can have attributes e.g.
"color:blue" or "severity:moderate" and based on those attributes
you can Style the points with different icons ...
For those who will stumble on this question like me..
It appears that the plugin has been generated (https://github.com/strk/mapnik/tree/2.3.x-pgraster) and has been merged in official Mapnik Repo.
The branch is 2.3.x (https://github.com/mapnik/mapnik/tree/2.3.x)
Now you can build Mapnik from the branch and use PGRaster plugin to use Raster data from ...
It's clear that it's not necessary to shift the projection, but the data.
Using GDAL >= 1.10.0 compiled with SQLite and SpatiaLite:
ogr2ogr russia_shifted.shp world.shp -dialect sqlite -sql "SELECT ShiftCoords(geometry,360,0) FROM world WHERE CNTRY_NAME='Russia'"
where shiftX = 360 (degrees) and shiftY = 0.
UPDATE: here's the whole workflow...
Just edit the renderd.conf and add a section for your second style (make sure the "URI" entry points to a different path than that of your default style). For example, my renderd.conf contains the sections
DESCRIPTION=This is the standard osm mapnik style
Like some suggested... I think your path from now should be:
Put data in some format supported by TileMill (if you want simplest, go with shapefiles, otherwise PostGIS database)
In Tilemill, load your data and define the symbolisation for your map, then export a Mapnik XML config file. You can use this XML file together with generate_tiles.py script to ...
Besides hardware and other software, rendering performance depends on the database, custom indexes, and the SQL in the style rendered. The style makes a huge difference, and badly written layer definitions can result in abysmal performance.
If you change the database schema, it requires changing both the custom indexes and layer SQL, so it's not possible to ...
The problem was almost certainly that you had a stray bracket:
renderd: An error occurred while loading the map layer 'default': Shape Plugin: shapefile '/usr/local/share/world)boundaries/shoreline_300.shp' does not exist (encountered during parsing of layer 'world' in map '/home/oleg/src/mapnik-style/osm.xml')
Note: world ) boundaries
Can you close ...
How big is your area of interest? For small regions (like a city, metropolitan area, or district), you can download data by BBOX using OSM Overpass API. For bigger areas - up to 24000000 sq km - BBike extract service will provide what you want. Anything bigger requires downloading continental extract/whole database dump, and clipping to BBOX using software ...
The problem you ran into has nothing to do with carto, it's an issue with your shell command, when you run sudo carto project.mml > OSMBright.xml carto runs as root, but the file write happens as your normal permission level, to do what your looking for you can sudo sh -c "carto project.mml > OSMBright.xml"
This page has a awesome tutorial of how to create a complete Tile server using the stack Mod_tile, renderd, mapnik, osm2pgsql and a postgresql/postgis database.
If you already have a style created by the Tilemill you can export to the Mapnik format and use it to generate your tiles and render with frameworks like OpenLayers and Leaflet.
It sounds like you first tried a source install of Mapnik. At this time input plugins were properly installed into the default directory at /usr/local/lib/mapnik/input. But the postgis plugin was not built because you did not have the pg_config program available and/or the postgres-devel package. If you followed http://github.com/mapnik/mapnik/wiki/...
The default OSM preview page's URL is ip_address:port_number/osm/preview.html#10/37.8000/-122.2600 which indicate the zoom level is 10, so I guess you did not export mbtiles file up to that zoom level that's why TileStache generates empty page then you could manually change the zoom level and lat/lon value to force TileStache to work out preview page.
There are a couple of options that might help you get the result you're after:
You could do this with the Python Imaging Libary (PIL) using the getcolors method on a image. For example:
from PIL import Image
im = Image.open(tile_path)
max_colors = 2 #if max colors is exceded in getcolors it returns None
if not im.getcolors(max_colors):
Most likely st_extent is not missing -> it is just undefined for geography types (that's what your error says).
It works on geometry types:
osm=# select st_extent('LINESTRING(1 2,3 4)'::geography);
ERROR: function st_extent(geography) does not exist
LINE 1: select st_extent('LINESTRING(1 2,3 4)'::geography);
HINT: No function matches the ...
Mapnik itself is basically just a rendering engine. As I understand, it can be used to render anything from tiles, to 8.5"x11", and even plotter-sized PDFs. To describe it very simply, Mapnik takes your data inputs, a spatial boundary, and a set of symbology styles (either hard-coded or an XML source), then it renders the map (potentially just a simple tile) ...
Here was my problem:
No way the SRTM data is that messed up.
The SRTM data IS that messed up. The warping above is actually in the DEMs in the SRTM3 dataset (downloaded from http://dds.cr.usgs.gov). After examining DEMs from the improved SRTM4 dataset (available here) I found that most of these "gaps" were filled by interpolation but other issues (...
Firstly, that is a LOT of data/tiles you are rendering, so you should expect it to take a long time.
You need to reconsider exactly what you are rendering. If you are using OSM_Bright and OSM data for the entire world at all zoom levels then consider more scale dependent rendering so that at the lower zoom levels, you are attempting to render less data. ...
Does anyone know how i can display the UTF Character overlays by themselves?
Something like this is done by glower - it'd be possible to just display all grids all the time.
i want to understand more about how this technology works. I assume the utfgrid overlays are drawing as vector tiles beneath the image tiles but firebug isn't showing me much.
Yes, you can build Mapnik to enable all postgres queries details to be output. See https://github.com/mapnik/mapnik/wiki/Runtime-Logging for more details.
However, it is easiest to just enable logging of postgres itself. One way that I frequently do this is to launch postgres from the command line like:
postgres -D /path/to/postgres/directory -c ...
Most probably you have a coastline in your download which is not closed. So the software can not decide on which side of the coastline is water, and on which side is land.
I don't know exatly how TileMill deals with it, but Mapnik renderer uses a separate shapefile with coastlines to avoide that mess.
Maybe you get lucky if you download the data with the ...
As mapperz pointed out, your load is probably small enough that anything you have will do. If you have some flexibility though, try for fast disks (ideally SSD) and more memory. I suggest fast disks and memory because these are likely to be the limiting factors (for the postgres database instance).
It is interesting to look how openstreetmap does it: http:/...