Changes between Version 8 and Version 9 of Processing/Wavelengths

Timestamp:

Aug 24, 2017, 3:36:18 PM (8 years ago)

Author:

dac

Comment:

Added info about using ENVI header with newer tools

Processing/Wavelengths

@@ -1 +1 @@
 = Sensor band information =
+
+== From ENVI header ==
+
+The centre wavelength and bandwith for hyperspectral data such as Eagle, Hawk, Fenix and Owl are stored within the ENVI header (.hdr) file associated with each binary (.bil) file.
+ 
+ENVI header files are plan text files and can be opened in any text editor such as [https://en.wikipedia.org/wiki/Microsoft_Notepad notepad].
+
+NERC-ARF also make a selection of tools available for extracting data from header files through https://github.com/pmlrsg/arsf_tools
+
+To extract the wavelength of each band to a CSV file the following can be used:
+
+{{{
+get_info_from_header.py f166011b.bil.hdr -o f166011b_wavelengths.csv
+}}}
+
+Within Python you can use:
+
+{{{#!python
+# Import envi_header module
+from arsf_envi_reader import envi_header
+
+# Read the header to a dictonary
+header_dict = envi_header.read_hdr_file("f166011b.bil.hdr")
+
+# Extract wavelengths, splitting into a list
+wavelengths = header_dict['wavelength'].split(',')
+
+# Convert from string to float (optional)    
+wavelengths = [float(l) for l in wavelengths]                               
+}}}
+
+== Using azgcor (for older data only) ==
+
+'''Note azgcor is no longer supplied or supported by NERC-ARF, please contact us if you wish to use folder data in HDF format.'''
 
 You can get the bandwidth information from an HDF files by running azexhdf on it.  The information is stored in several vectors in the HDF.
@@ -14 +48 @@
 The ATM vectors will never vary.  You can use the CSV file at the bottom of this page for ATM.
 
-== Example commands ==
+=== Example commands ===
 
 General form: