having a problem with wrong extent

[Tobias Wendorff-2]

Hi there,

I've got some offset when rendering single images using Mapnik.

I've imported an extract of OpenStreetMap-data [1] into my PostGIS
using "osm2pgsql -c -l dortmund.osm", which means: stores as
EPSG:4326 (+proj=latlong +ellps=WGS84 +datum=WGS84) instead of
Spherical Mercator (SM).

"SELECT srid FROM geometry_columns;" returns 4326 as expected.

I've edited the template stylefile [2] to make it work on my
system (correct parth, login to my PostGIS database).

I've also removed the hardcoded extent, which belongs to SM, and
set <Parameter name="estimate_extent">true</Parameter>.

Here is my mapfile, a very simple one: [3]
------------------------------------------------------------------------
#!/usr/bin/python
from mapnik import *

# create map
m = Map(500, 500)
load_map(m, 'osm.xml')

# set map-buffer to avoid labeling problems at edges
m.buffer_size = 250

bbox = Envelope(7.50273893442,51.4803224939,7.50978821362,51.4849072287)
m.zoom_to_box(bbox)
im = Image(m.width, m.height)
render(m, im)
im.save('test.png', 'png')
------------------------------------------------------------------------

It creates this image: [4]
But this image doesn't have the correct bbox / extent.
This is what it should look like: [5] (this source is accurate).

Could anyone please tell me, what I am doing wrong?

I'm running Mapnik v0.6.1 with proj.4 v4.6.1 on Debian Testing.
Same problem occures on latest Mapnik from SVN.

Best regards,
Tobias

References:
[1] 2.65 MB, 7zip: http://depot.tu-dortmund.de/get/7fqz7k
[2]
http://svn.openstreetmap.org/applications/rendering/mapnik/osm-template.xml
[3] http://pastebin.com/m7e2de5b5
[4] http://depot.tu-dortmund.de/get/e2yx5r
[5] http://tiny.cc/m01
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[Dane Springmeyer]

Tobias,

What happens if you try adding this line to your python script (before setting the bbox)?

m.aspect_fix_mode = aspect_fix_mode.GROW_CANVAS

Dane

On Sep 8, 2009, at 11:38 AM, Tobias Wendorff wrote:

Hi there,

I've got some offset when rendering single images using Mapnik.

I've imported an extract of OpenStreetMap-data [1] into my PostGIS
using "osm2pgsql -c -l dortmund.osm", which means: stores as
EPSG:4326 (+proj=latlong +ellps=WGS84 +datum=WGS84) instead of
Spherical Mercator (SM).

"SELECT srid FROM geometry_columns;" returns 4326 as expected.

I've edited the template stylefile [2] to make it work on my
system (correct parth, login to my PostGIS database).

I've also removed the hardcoded extent, which belongs to SM, and
set <Parameter name="estimate_extent">true</Parameter>.

Here is my mapfile, a very simple one: [3]
------------------------------------------------------------------------
#!/usr/bin/python
from mapnik import *

# create map
m = Map(500, 500)
load_map(m, 'osm.xml')

# set map-buffer to avoid labeling problems at edges
m.buffer_size = 250

bbox = Envelope(7.50273893442,51.4803224939,7.50978821362,51.4849072287)
m.zoom_to_box(bbox)
im = Image(m.width, m.height)
render(m, im)
im.save('test.png', 'png')
------------------------------------------------------------------------

It creates this image: [4]
But this image doesn't have the correct bbox / extent.
This is what it should look like: [5] (this source is accurate).

Could anyone please tell me, what I am doing wrong?

I'm running Mapnik v0.6.1 with proj.4 v4.6.1 on Debian Testing.
Same problem occures on latest Mapnik from SVN.

Best regards,
Tobias

References:
[1] 2.65 MB, 7zip: http://depot.tu-dortmund.de/get/7fqz7k
[2]
http://svn.openstreetmap.org/applications/rendering/mapnik/osm-template.xml
[3] http://pastebin.com/m7e2de5b5
[4] http://depot.tu-dortmund.de/get/e2yx5r
[5] http://tiny.cc/m01
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Mapnik-users@...
https://lists.berlios.de/mailman/listinfo/mapnik-users

_______________________________________________
Mapnik-users mailing list
Mapnik-users@...
https://lists.berlios.de/mailman/listinfo/mapnik-users