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We would like to suggest the following as a "starting point" that we
can refine toward the goal of agreeing on a "basic" set of metadata
and structure. It is an example of a multi-banded image structure
that contains navigation on a point-by-point basis, and provides for
linear calibration. The variable "names" are not critical, but the
"standard_name" should be used by applications to identify the
quantity.
(In the following, most of the numbers are just samples....to make it
more readable...)
dimensions:
x = 5304 ;
y = 2438 ;
band=16
variables:
float lat(y, x);
lat:standard_name = "latitude" ;
lat:units = "degrees_north" ;
lat:valid_range = -90.f, 90.f ;
float lon(y, x) ;
lon:standard_name = "longitude" ;
lon:units = "degrees_east" ;
lon:valid_range = -180.f, 180.f ;
int band(band);
double time;
time:long_name = "Nominal time of image";
time:units="s since 1990-1-1 0:0:0";
string bandname(band);
bandname:standard_name = "band_name" ;
float offset(band) ;
offset:standard_name="linear_calibration_offset";
float scale(band) ;
scale:standard_name="linear_calibration_scale_factor";
float wavelength(band);
wavelength:standard_name="radiation_wavelength";
wavelength:units="micron";
string units(band);
units:standard_name="band_units";
short ImageData(band, y, x) ;
ImageData:coordinates = "band lat lon" ;
ImageData:valid_min = 1s ;
ImageData:_FillValue = 0s ;
ImageData:missing_value = 0s ;
and for people who want/need to use a table look-up for calibration --
instead of the "linear_calibration..."
variables, we would use:
float lookup(band, 256);
lookup:standard_name="calibration_lookup_table";
As Russ Rew pointed out, if there is only one band, it would be
possible to dimension the Data as (y,x) but have the coordinates
attribute contain "band".
tom
(with help from Tom Rink and Kaba Bah)
--
Tom Whittaker
University of Wisconsin-Madison
Space Science & Engineering Center (SSEC)
Cooperative Institute for Meteorological Satellite Studies (CIMSS)
1225 W. Dayton Street
Madison, WI 53706 USA
ph: +1 608 262 2759
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