Hi William,
On May 26, 2009, at 2:17 PM, william clapham wrote:
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
How did you come up with that?
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
_______________________________________________
Mapnik-users mailing list
[email protected]
https://lists.berlios.de/mailman/listinfo/mapnik-users
