I am new to Mapnik, so I am not sure if this is a bug or I am just doing
something wrong.
I am trying to use an s57 (NOAA ENC .000) file as the datasource and extract
multiple layers from the same file.
I am using Mapnik2 from http://dbsgeo.com/downloads/ on OS X 10.6.6 with the
Kyngchaos 1.8 framework distribution.
I have no problem extracting one layer at a time and generating a mapnik map
but if I try to use two layers then mapnik crashes with
a segmentation fault. Either layer works fine independently (I tried several
different layers and they all work independently but any
time I use more than one layer I get the fault.
The seg fault is caused when I call mapnik.Ogr() the second time as in:
seaData = mapnik.Ogr(file= srcPath, layer='SEAARE')
landData = mapnik.Ogr(file= srcPath, layer='LNDARE') #seg fault occurs here
Also the first time in the same python session in a terminal that I try to use
two layers I get a cryptic warning but both layers plot.
Any subsequent attempts produce the seg fault. I have to close the terminal
window to "reset" something in mapnik, that then produces the warning,and then
subsequent seg faults. I would guess that Mapnik is locking up a resource
associated with the file that should be reentrant
but is not. (Or maybe its me)
Here is the warning.
Warning 1: Illegal feature attribute id (ATTF:ATTL[0]) of 116
on feature FIDN=333014085, FIDS=4843.
Skipping attribute, no more warnings will be issued.
The code is below
def TestENC(srcFile, dstFile):
"""Generates map image from NOAA ENC format source file (S57 .000)
specified by srcFile. If srcFile has extension .000 then extracts base
if not then uses srcFile as base
so that complete path to source is given by
../data/ENC/Florida/base/base.000
Saves map image as .png in folder ../maps/ with file name dstFile
Usage: mapt.TestENC('US5FL88M', 'Test188')
"""
import mapnik2 as mapnik
base, ext = os.path.splitext(srcFile)
if ext not in['.000']:
srcFile = '.'.join([srcFile, '000'])
base, ext = os.path.splitext(srcFile)
srcPath = os.path.join("../data/ENC/Florida/",base, srcFile)
print "Source file = %s" % srcPath
base, ext = os.path.splitext(dstFile)
if ext not in ['.png']:
dstFile = '.'.join([dstFile, 'png'])
dstPath = os.path.join( "../maps/", dstFile)
print "Destination file = %s" % dstPath
MIN_LAT = 27.475
MAX_LAT = 27.490
MIN_LONG = -80.32
MAX_LONG = -80.25
MAP_WIDTH = 800
MAP_HEIGHT = 600
print "Setting up styles"
# Set up our "Sea Area" layer styles
seaStyle = mapnik.Style()
rule = mapnik.Rule()
symbol = mapnik.PolygonSymbolizer(mapnik.Color('rgb(0%,20%,80%)'))
rule.symbols.append(symbol)
seaStyle.rules.append(rule)
rule = mapnik.Rule()
symbol = mapnik.LineSymbolizer(mapnik.Color('rgb(0%,0%,0%)'), 0.1)
rule.symbols.append(symbol)
seaStyle.rules.append(rule)
# Set up our "Land Area" layer styles.
landStyle = mapnik.Style()
rule = mapnik.Rule()
#rule.filter = mapnik.Filter("[NAME] = 'Angola'")
symbol = mapnik.PolygonSymbolizer(mapnik.Color('rgb(15%,80%,15%)'))
rule.symbols.append(symbol)
landStyle.rules.append(rule)
rule = mapnik.Rule()
symbol = mapnik.LineSymbolizer(mapnik.Color('rgb(0%,0%,0%)'), 0.1)
rule.symbols.append(symbol)
landStyle.rules.append(rule)
print "Setting up layers"
# Set up our map layers.
print "Setting up sea layer"
# Sea Layer
# Set up datasource for layer
seaData = mapnik.Ogr(file= srcPath, layer='SEAARE')
# Setup layer and attach data and styles
seaLayer = mapnik.Layer("Sea")
seaLayer.datasource = seaData
seaLayer.styles.append("seaStyle")
print "Setting up land layer"
# Land Layer
# Set up datasource for layer
#*************** Next line causes the fault *************/
landData = mapnik.Ogr(file= srcPath, layer='LNDARE')
# Setup layer and attach data and styles
landLayer = mapnik.Layer("Land")
landLayer.datasource = landData
landLayer.styles.append("landStyle")
# Create our map.
# +proj=longlat means use units of angular degrees
map = mapnik.Map(MAP_WIDTH, MAP_HEIGHT, "+proj=longlat +datum=WGS84")
map.background = mapnik.Color('rgb(80%,80%,80%)')
map.append_style("landStyle", landStyle)
map.append_style("seaStyle", seaStyle)
map.layers.append(seaLayer)
map.layers.append(landLayer)
# Finally, render the map.
print "Rendering Map"
map.zoom_to_box(mapnik.Envelope(MIN_LONG, MIN_LAT, MAX_LONG, MAX_LAT))
mapnik.render_to_file(map,dstPath, "png")
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Samuel M. Smith Ph.D.
242 East 600 North, Lindon Utah 84042-1662 USA
801-768-2768 voice
801-768-2769 fax
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"The greatest source of failure and unhappiness in the world is
giving up what we want most for what we want at the moment"
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