Hello all,
I'm attempting to create geoTiff images from a large number of netCDF
files.
A portion of my test code is below:
LatLonPointImpl p1 = new LatLonPointImpl(38.0625, -80.6875); // lower
left
LatLonPointImpl p2 = new LatLonPointImpl(47.8125, -67.0625); // upper
right
LatLonRect llr = new LatLonRect(p1, p2);
GeotiffWriter writer = new GeotiffWriter
("NE_1961-1990_Yearly_Max_Temp.tif");
writer.writeGrid("NE_1961-1990_Yearly_Max-Temp.nc", "tmax", 0, 0,
true, llr);
(netCDF file here: http://temagami.tosm.ttu.edu/~jvandorn/netcdf/
NE_1961-1990_Yearly_Max_Temp.nc)
This does produce a viewable image from the netCDF file:
(viewable here: http://temagami.tosm.ttu.edu/~jvandorn/netcdf/
netcdfLibToTiffGrayScaleTrue.tif)
However the pixel values in the tif image when viewed in something
that works with geoTiffs (e.g., Mirone) do not reflect their original
values. Meaning, the original input netCDF file is showing maximum
temperatures (http://temagami.tosm.ttu.edu/~jvandorn/netcdf/
NE_1961-1990_Yearly_Max_Temp.png), which roughly range from 7 to 25
oC (with a missing value of -999), but the resulting tiff scale seems
to range from 1 to 255.
Per the API, there's a boolean greyScale setting in the
GeotiffWriter.writeGrid method. Is this the expected result when
that is set to true? That it outputs a grey scale image, where the
pixel values are now in terms of 1 to 255, instead of their original
values?
I've tried setting grayScale to false, in hopes that it would
actually retain the original data values but nothing really seems to
make much sense of that result:
(http://temagami.tosm.ttu.edu/~jvandorn/netcdf/
netcdfLibToTiffGrayScaleFalse.tif).
So, my basic question is, can I produce a geoTiff image that will
contain the same range of pixel (i.e., data) values that the original
netCDF file shows?
Thank you for any help/suggestions on this.
Jeff
