Problem with Mapnik and custom XML-File

Question

I'm right now working with navteq data and building 'the XML-File' to generate the tiles!

I started with an all original osm.xml, and set all the status' to "off". First I checked the dataset in my database with SRID(the_geom) and got a return "SRID:4326". So I set up the layer to SRID4326 instead of SRID900913.

<Layer name="myLayer" status="on" srs="+init=epsg:4326">

My pgSQL query was written according to the OSM query:

(select the_geom, 'true' as "water", polygon_nm as "name"
      from waterseg ) as myLayer

The next step was to setup the stylesheet. I did that - set the max and min zoom level to the maxima. So the zoomlevels should influence the rendering.

But it's not working. I can't see a single stroke on the image. I just get an empty picture. I tried to look through the file and see if there is any problem with a potential z-level - don't think so. Next was to check the bounds - no matter if I set bounds as 900913 or 4326 the image is still the same.

I assume strongly, that I have somewhere a problem with the projections. Can anyone help me? Has anyone ever tried to render a full map from scratch, without the predefined stylesheet!

Thanks

Answer 1

Martin,

Have you remembered to also set the Map level srs to "+init=epsg:4326"? Also, you need to explain how you are actually rendering the image otherwise it is hard to help further. I recommend using nik2img which has a --verbose flag and get help you understand when you've mixed up coordinate systems and/or the map bounds.

Answer 2

the problem is your projection setting.

set the layer srs with 4326. and set map srs with any projection you want to generate map .

map srs :

srs: Coordinate system in which the map is rendered (for instance '+proj=latlong+datum=WGS84' for a WGS84 Geographic coordinate system)

layer srs :

srs: Default inherits from map.srs; Reference system from the the project Proj.4. e.g. +proj=latlong +datum=WGS84

take a look at Mapnik XML Documentation