Re: Help rendering image with manifold + mapnik combo

Hello all - I'm a relative newbie/first time poster looking for a little help.  I've been trying to do something a little unorthodox here in the world of GIS, using a combination of tools (Manifold Enterprise 8.0.12 + postgres 8.3.5/postgis db + mapnik 0.6) to draw a fictional world, and find myself beating my head on the desk when i keep drawing blank maps.

Blank maps usually indicate a mis-match in coordinates used for the bounding box or the use of a coordinate system that does not work with the data being used.

Also, is there a way to build mapnik in windows to run in debug mode?  i'm kinda flying blind with no feedback.

No, there is not. You can download nik2img.py however and run that against a Mapnik XML file in verbose mode, which outputs information on your map bounding box and which data layers intersect it. Seeing that the bbox does not match the layer coordinates is often helpful for noticing problems with your usage of coordinate systems.

--Some quick facts:

 The environment envelope (in LatLong) is 0, 0, 0.375, 0.375

and I've tried exporting to postgres using WGS84/ll as well as projecting it to Mercator (then re-projecting it to the specific SRID in my spatial_ref_sys).

 If i export everything to unprojected local SHP files from manifold, Mapnik will draw everything just fine.

 Also on the mapnik side, i can draw real world OpenStreetMap data from our postgres/gis db just fine, using the standard generate_tiles.py / xml mapfile combo.

Okay.

 I have been using the same python script / mapfile combo for my fictional data and simply changing the postgis db info to my own, and the render envelope to fit my area. (i've been using the native extent bounds for the given srs)

 After an export to the postgres/gis db, i can view my fictional world data in Safe FME, and QGIS (so it's technically there)...but projections cannot be verified, and mapnik wont draw it.

Using which projection? If you are using mercator you will need to change your bounding box to fix mercator coordinates. And you'll need to make sure that your data is appropriate for mercator, since that projection does not allow, for example, coordinates on the earths surface greater than 90 degrees north/south.

Dane