ugrid2shp

This python code computes GIS shapefiles from a CF-UGRID compliant netCDF file. The contours are generated in matplotlib, and output using Shapely and Fiona.

###System Requirements

• Python 2.7.x
• Shapely
  • https://pypi.python.org/pypi/Shapely
• Fiona (Geospatial Data Abstraction Library (GDAL) OGR interface
  • https://pypi.python.org/pypi/Fiona
• libcurl
  • OPeNDAP dependency.
  • http://curl.haxx.se/libcurl/
• libhdf5 C library
  • Dependency for NetCDF4.
  • http://www.hdfgroup.org/HDF5/release/obtain5.html
  • See notes section if installing on a mac - there is an easier way.
• netCDF4 C library
  • http://www.unidata.ucar.edu/downloads/netcdf/index.jsp
  • See notes section if installing on a mac - there is an easier way.
• netcdf4-python
  • The netCDF4/libhdf5 C libraries must be installed before installing netcdf4-python.
  • https://pypi.python.org/pypi/netCDF4
• shell-doctest
  • This python library is needed to run doc tests.
  • https://pypi.python.org/pypi/shelldoctest

###Notes: On a mac using the homebrew package manager (http://brew.sh/), the homebrew/science tap (https://github.com/Homebrew/homebrew-science) can be used to simplify installation of the HDF5 and netCDF4 C libraries needed for building netcdf4-python. After installing homebrew, add the homebrew-science tap, then install the HDF5 and netCDF4 C libraries from the homebrew-science tap

###Usage:

ugrid2shp.py -h -d -s -w -x -z -n <NcFileName|url> -o <OutFile> -v <NcVariableName> -a <MinVal> -b <MaxVal> -c <NumLevels> -l <AxisLims> -p <ProjectionString>

where:	-h | --Help				the text you are looking at right now
		-d | --Debug				display debugging diagnostics [False]
		-s | --Silent				no screen diagnostic output [True]
		-w | --WriteImage			write matplotlib image to a file <outfile>.png [False]
		-x | --ShowImage			display matplotlib image, user must close before continuing [False]
		-z | --NoZip				no zip file output [False]
		-n | --NcFileName	<ncfilename> 	netCDF file to read from, or a URL to an OPeNDAP file [maxele.63.nc]
		-o | --OutFile		<outfilename> 	filename to write shapefile to [outShape]
		-v | --NcVarName	<NcVarName> 	netCDF variable name to render [zeta_max]
		-a | --MinVal		<min value> 	smallest scalar value to render [0]
		-b | --MaxVal		<max value> 	largest scalar value to render [10]
		-c | --NumLevels	<num levels> 	number of contour levels [11]
		-l | --AxisLims		<[x0 y0 x1 y1]> axis limits to clip to [full domain]
		-p | --ProjStr				Projection string for prj file;  see below.

A projection file (prj) is written containing the following:
	GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]
To specify a different projection string, pass in -p | --ProjStr <projstr>, where projstr is as in this example:
	--ProjStr 'GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]' 

###Example usage:

$ Define url=http://opendap.renci.org:1935/thredds/dodsC/ASGS/nam/2013112112/ec95d/hatteras.renci.org/cfsamp/namforecast/maxele.63.nc 
$ Run silently (-s) pointing to the url devined above (-n $url), and with the maximum scalar value set to 6 (-b 6) 
$ python ugrid2shp.py -s -n $url -b 6
$ The first image is the matplotlib figure.  The second is the shapefile in QGIS.  the colormaps are not the same, but the contour lines are in the same locations.

###Test URLs: Coarse resolution ADCIRC grid: http://opendap.renci.org:1935/thredds/dodsC/ASGS/nam/2013112112/ec95d/hatteras.renci.org/cfsamp/namforecast/maxele.63.nc Medium resolution ADCIRC grid: http://opendap.renci.org:1935/thredds/dodsC/ASGS/andrea/08/nc6b/blueridge.renci.org/fivemem/nhcConsensus/maxele.63.nc