| Re: Routine for Converting DN to Radiance to Temperature [message #54989] |
Fri, 27 July 2007 15:08  |
James Kuyper
Messages: 425
Registered: March 2000
|
Senior Member |
|
|
Paul van Delst wrote:
> Conor wrote:
>> On Jul 26, 5:12 pm, Marsh...@gmu.edu wrote:
>>> Hi dears:
>>> Can someone help me how to write routine for converting Digital Number
>>> to Radiance to Temperature for MASTER bands (HDF format) in IDL?
...
> But, given that the MASTER instrument has been used pretty extensively,
>
> http://master.jpl.nasa.gov/
Following that link, I learned that MASTER data is stored in the same
format as MAS data, and the format is documented at <http://
mas.arc.nasa.gov/reference/hdfread.txt>. The CalibratedData SDS has an
SDS attribute named "scale_factor" which is a 50 element array, and
another one named "units" with a value of "watts/meter2/steradian/
micron". The middle dimension of the CalibratedData array is also 50,
which appears to be the number of bands of data. Therefore, I'd hazard
a guess that, in order to obtain a value with those units for a given
band, you just calculate:
radiance = CalibratedData[*,band,*]*scale_factor[band]
The file specification has many references to temperatures, but they
look like instrument temperatures, whereas I suspect you're interested
in the brightness temperature. However, if you know what the
brightness temperature is, you should know how to calculate it from
the radiance.
If you need help reading HDF data, look in the IDL online help for
HDF_SD_Start()/HDF_SD_Close, HDF_SD_NameToIndex(), HDF_SD_Select()/
HDF_SD_EndAccess, HDF_SD_GetData, HDF_SD_AttrFind(), and
HDF_SD_AttrInfo().
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
