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Band of data missing in netcdf file
- Subject: Band of data missing in netcdf file
- Date: Wed, 24 Jan 2007 20:24:49 -0800
Hi Folks,
I've got a weird one for you.
I have a process that writes out netcdf files that typically works fine. The
process takes an array of lat/lon values and for each element in the array it
increments a 2D array in my netcdf file. The 2D array is essentially a counter
for the number of lat/lon values in my initial array that map to each pixel (in
lat/lon space) in my netcdf file. However, there is an abnormal case that shows
up when I write a large number of times to the netcdf file (1050705 times)
where a horizontal band of the data in the netcdf seems to be getting lost
somewhere.
Here's what I've done to test:
Written smaller netcdf files using the exact same code with data in the missing
zone. The data in this test case shows up fine.
Stepped through with a debugger to make sure my code is actually writing the
values into the netcdf array, I can see the values being entered and feel
confident that this is working.
I've viewed the data file in multiple data viewers to make sure it isn't a
glitch in the data viewer (openev, gdal_translate (to an image))
About my setup:
I'm using netcdfUI-2.2.18.jar (was using 2.2.16, but updated before sending
this email, to make sure).
Writing my data to a ucar.ma2.ArrayInt (and my values aren't coming near
overflowing the 16bit limit)
Java 1.5.0_3
Windows XP
Here's a snapshot of what the problem looks like when visualized:
http://www.mbari.org/staff/achase/vdm/netcdf-wierdness.jpg
The banding I'm referring to is right in the middle of the screen. I set the
viewing options to show pixels with any value as white and no data as black.
Any thoughts? Anybody come across a problem like this before?
Here's the gdalinfo output for the file:
Driver: netCDF/Network Common Data Format
Size is 512, 512
Coordinate System is `'
Metadata:
NC_GLOBAL#creationDate=01/24/2007
NC_GLOBAL#lastModified=01/24/2007
NC_GLOBAL#description=Test File
NC_GLOBAL#title=Test Data
NC_GLOBAL#keywords=test
NC_GLOBAL#Conventions=CF-1.0
Subdatasets:
SUBDATASET_1_NAME=NETCDF:"physical-object.nc":physical-object
SUBDATASET_1_DESC=[4001x5001] physical-object (16-bit integer)
Corner Coordinates:
Upper Left ( 0.0, 0.0)
Lower Left ( 0.0, 512.0)
Upper Right ( 512.0, 0.0)
Lower Right ( 512.0, 512.0)
Center ( 256.0, 256.0)
And for the variable in question:
C:\workspace\vdm\snapshot_creator>gdalinfo NETCDF:"physical-object.nc":physical-
object
Driver: netCDF/Network Common Data Format
Size is 5001, 4001
Coordinate System is `'
Origin = (-125.000000000000000,38.000999999999998)
Pixel Size = (0.000999800039992,-0.000999750062484)
Metadata:
NC_GLOBAL#creationDate=01/24/2007
NC_GLOBAL#lastModified=01/24/2007
NC_GLOBAL#description=Test File
NC_GLOBAL#title=Test Data
NC_GLOBAL#keywords=test
NC_GLOBAL#Conventions=CF-1.0
physical-object#units=count
physical-object#fillvalue=0
physical-object#missing_value=0
latitude#units=degrees_north (+N/-S)
longitude#units=degrees_east (+E/-W)
Corner Coordinates:
Upper Left (-125.0000000, 38.0010000)
Lower Left (-125.0000000, 34.0010000)
Upper Right (-120.0000000, 38.0010000)
Lower Right (-120.0000000, 34.0010000)
Center (-122.5000000, 36.0010000)
Band 1 Block=5001x1 Type=Int32, ColorInterp=Undefined
NoData Value=0
Metadata:
NETCDF_VARNAME=physical-object
Thanks,
Andrew
Andrew C. Chase
Software Engineer
Monterey Bay Aquarium Research Institute
(831) 775-1865 :: Work
(831) 419-8566 :: Cell [NOTE: New number as of May 22, 2005]
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