1. Start IDL. 2. Click the New File icon. 3. Copy and paste the example spatial reader code into the IDL Editor window.

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1 Custom Open Procedure Tutorial This tutorial demonstrates the steps to open a custom data file that contains embedded metadata. You will run the open procedure from the ENVI menu. Verify the Custom Code Directory Preference Setting Create a Spatial Read Routine Create a Spectral Read Routine Create a Custom Open Procedure Write Metadata to a Data File Run the Custom Open Procedure Verify the Custom Code Directory Preference Setting In this tutorial, you will save the custom open procedure and spatial and spectral routines to the directory specified in the Custom Code Directory preference setting. 1. Start ENVI. 2. Select File > Preferences. 3. On the left side of the Preferences dialog, select Directories. 4. Note the directory next to Custom Code Directory. The default locations are as follows, where x_x is the ENVI version number: Windows 7 and 8: C:\Users\username\.idl\envi\custom_codex_x Linux: /home/username/.idl/envi/custom_codex_x 5. Exit ENVI. Create a Spatial Read Routine 1. Start IDL. 2. Click the New File icon. 3. Copy and paste the example spatial reader code into the IDL Editor window. Page 1 of 12

2 4. Save the file as example_custom_metadata_spatial.pro in the custom code directory. Create a Spectral Read Routine (Optional) 1. Click the New File icon in the IDL toolbar. 2. Copy and paste the example spectral reader code into the IDL Editor window. 3. Save the file as example_custom_metadata_spectral.pro in the custom code directory. Create a Custom Open Procedure 1. Click the New File icon in the IDL toolbar. 2. Copy and paste the example code for a custom open procedure into the IDL Editor window. 3. Save the file as example_open_custom_metadata.pro in the custom code directory. Write Metadata to a Data File 1. Click the New File icon in the IDL toolbar. 2. Copy and paste the example code for writing metadata to a file into the IDL Editor window. 3. Save the file as write_envi_custom_file_embedded_header.pro in your IDL workspace. 4. Compile the program. Run the Custom Open Procedure 1. Copy and paste the following code into the IDL command line. This code opens the file qb_boulder_msi (provided in the ENVI installation) and reads information about the file from its associated header. e = ENVI() file = FILEPATH('qb_boulder_msi', ROOT_DIR = e.root_dir, $ Page 2 of 12

3 SUBDIRECTORY = ['data']) raster = e.openraster(file) data = raster.getdata() datatypelist = ['', 'byte', 'int', 'long', 'float', 'double', $ 'complex', '', '', 'dcomplex', '', '', 'uint', 'ulong', $ 'long64', 'ulong64'] datatype = Where(dataTypeList EQ raster.data_type) write_envi_custom_file_embedded_header, data, $ BANDS = raster.nbands, $ DATA_TYPE = datatype, $ INTERLEAVE = raster.interleave, $ LINES = raster.nrows, $ SAMPLES = raster.ncolumns, $ STORAGE_DATA_TYPE = 12, $ SCALE_FACTOR = 1, $ MIN_VALUE = 0 2. When prompted, select a filename and directory for writing a custom data file. The above code calls the procedure write_envi_custom_file_embedded_ header, which writes the required and custom metadata to a new file. 3. From the menu bar, select File > Open As > Custom > Example Custom Format > Open Custom File to Float. A file selection dialog appears. 4. Select the custom file you created in Step 2, and click Open. The file displays. 5. Right-click on the filename in the Layer Manager and select View Metadata. 6. Select Raster in the left side of the Metadata Viewer, and verify that the Type is "Custom" and the Data Type is "Float." 7. See the topic "Write a Custom Open Procedure" in ENVI Help for details on the procedure used in this example. Page 3 of 12

4 Example Code for Spatial Read Routine (Custom Open Procedure) PRO example_custom_metadata_spatial, unit, data, fid, band, $ xs, ys, xe, ye, _EXTRA = extra COMPILE_OPT IDL2, hidden ; Define a general Catch block CATCH, err IF err NE 0 THEN BEGIN CATCH, /CANCEL data =!NULL RETURN IF ENVI_FILE_QUERY, fid, NS = ncolumns, NL = nlines, NB = nbands, $ INTERLEAVE = interleave, DATA_TYPE = rastertype, $ BYTE_SWAP = byteswap, OFFSET = datastart, P_INFO = pinfo ; Get the values of Scale Factor, Min Value, and storage type scalefactor = (*pinfo).scalefactor minvalue = (*pinfo).minvalue storagetype = (*pinfo).storagetype ; Determine how many bytes each data element contains numbyteslist = [0L,1,2,4,4,8,8,0,0,16,0,0,2,4,8,8] bytesperelement = numbyteslist[storagetype] ; Get the data CASE interleave OF 0: BEGIN readstart = datastart + bytesperelement * $ (ncolumns*nlines*band + ys*ncolumns) readdata = ASSOC(unit, MAKE_ARRAY(nColumns, nlines, /NOZERO, $ TYPE = storagetype), readstart) data = (readdata[0])[xs:xe, ys:ye] 1: BEGIN readdata = ASSOC(unit, MAKE_ARRAY(nColumns, nbands, $ nlines, /NOZERO, TYPE = storagetype), datastart) Page 4 of 12

5 data = REFORM((readData[0])[xs:xe, band, ys:ye], /OVERWRITE) 2:BEGIN readdata = ASSOC(unit, MAKE_ARRAY(nBands, ncolumns, $ nlines, /NOZERO, TYPE=storageType), datastart) data = REFORM((readData[0])[band, xs:xe, ys:ye], /OVERWRITE) CASE ; Check byte order IF (byteswap) THEN BYTEORDER, data, scalefactor, minvalue ; Finally, convert the data using the data type in the ENVI header and the ; min value and scale factor values defined above. data = FIX(data, TYPE = rastertype) data *= FIX(scaleFactor, TYPE = rastertype) data += FIX(minValue, TYPE = rastertype) Page 5 of 12

6 Example Code for Spectral Read Routine (Custom Open Procedure) PRO example_custom_metadata_spectral, fid, band, XS=xs, XE=xe, Y=y, $ SPECTRA=spectra, _EXTRA=extra COMPILE_OPT IDL2, hidden ; Define a general Catch block CATCH, err IF err NE 0 THEN BEGIN CATCH, /CANCEL spectra =!NULL RETURN IF ENVI_FILE_QUERY, fid, FNAME = filename, NS = ncolumns, NL = nlines, NB = nbands, $ INTERLEAVE = interleave, DATA_TYPE = rastertype, BYTE_SWAP = byteswap, $ OFFSET = datastart, P_INFO = pinfo ; If bands are not specified, use all the bands IF (N_ELEMENTS(band) EQ 0) THEN band = LINDGEN(nBands) ; Get number of bands used nbandsout = N_ELEMENTS(band) IF (N_ELEMENTS(xs) EQ 0) THEN xs = 0L IF (N_ELEMENTS(xe) EQ 0) THEN xe = LONG(nColumns-1) OPENR, unit, filename, /GET_LUN ; Get the values of Scale Factor, Min Value, and storage type scalefactor = (*pinfo).scalefactor minvalue = (*pinfo).minvalue storagetype = (*pinfo).storagetype ; Determine how many bytes each data element contains numbyteslist = [0L,1,2,4,4,8,8,0,0,16,0,0,2,4,8,8] bytesperelement = numbyteslist[storagetype] Page 6 of 12

7 ; Get the data CASE interleave OF 0: BEGIN readstart = bytesperelement * (LINDGEN(nBands) * ncolumns * $ nlines + y * ncolumns) + datastart spectra = MAKE_ARRAY(nColumns, nbands, /NOZERO, TYPE = storagetype) FOR i=0l, nbands-1 DO BEGIN readdata = ASSOC(unit, MAKE_ARRAY(nColumns, /NOZERO, $ TYPE = storagetype), readstart[i]) spectra[*,i] = readdata[0] FOR spectra = spectra[xs:xe, band] 1: BEGIN readstart = bytesperelement * ncolumns * nbands * y + datastart readdata = ASSOC(unit, MAKE_ARRAY(nColumns, nbands, $ /NOZERO, TYPE = storagetype), readstart) spectra = (readdata[0])[*, band] 2: BEGIN readstart = bytesperelement * ncolumns * nbands * y + datastart readdata = ASSOC(unit, MAKE_ARRAY(nBands, ncolumns, $ /NOZERO, TYPE = storagetype), readstart) spectra = (readdata[0])[band, *] CASE ; Check byte order IF (byteswap) THEN BYTEORDER, spectra, scalefactor, minvalue ; Convert the data using the data type in the ENVI header and the ; min value and scale factor values defined above. spectra = FIX(spectra, TYPE = rastertype) spectra *= FIX(scaleFactor, TYPE = rastertype) spectra += FIX(minValue, TYPE = rastertype) FREE_LUN, unit Page 7 of 12

8 Example Code for a Custom Open Procedure PRO example_open_custom_metadata_custom_reader_init e = ENVI(/CURRENT) e.addcustomreader, 'Open Custom File to Float', $ 'example_open_custom_metadata', $ PATH = 'Example Custom Format', UVALUE = 'float' e.addcustomreader, 'Open Custom File to Double', $ 'example_open_custom_metadata', $ PATH = 'Example Custom Format', UVALUE = 'double' PRO example_open_custom_metadata, file, UVALUE = uvalue, R_FID = r_ fid COMPILE_OPT IDL2 IF (N_elements(file) EQ 0) THEN BEGIN file = DIALOG_PICKFILE(/READ) IF IF (~KEYWORD_SET(file)) THEN RETURN ; Open the file and read the embedded header OPENR, unit, file, /GET_LUN byteorder = BYTE(0) headerstring = string('', FORMAT = '(A15)') READU, unit, byteorder, headerstring ; If header string does not read 'ENVIEmbeddedHDR' then the file is not ; the file type defined in this example. IF (headerstring NE 'ENVIEmbeddedHDR') THEN RETURN ns = LONG64(0) nl = LONG64(0) nb = LONG64(0) interleave = BYTE(0) scalefactor = DOUBLE(0) minvalue = DOUBLE(0) storagetype = BYTE(0) descriptionlen = 0s READU, unit, ns, nl, nb, interleave, scalefactor, minvalue, $ storagetype, descriptionlen IF (descriptionlen GT 0) THEN BEGIN Page 8 of 12

9 format = STRCOMPRESS('(A'+STRING(descriptionLen)+')', /REMOVE_ALL) description = STRING('', FORMAT=format) READU, unit, description IF ELSE BEGIN description = '' ELSE ; Use the UVALUE to determine which button was clicked. ; This determines whether the data will be opened as float or double. IF (uvalue EQ 'float') THEN datatype = 4 ELSE datatype = 5 info = {scalefactor:scalefactor, $ minvalue:minvalue, $ storagetype:storagetype} headeroffset = 60+descriptionLen readprocedures = ['example_custom_metadata_spatial', $ 'example_custom_metadata_spectral'] ENVI_SETUP_HEAD, BYTE_ORDER = byteorder, $ DATA_TYPE = datatype, $ DESCRIP = description, $ FNAME = file, $ INTERLEAVE = interleave, $ NB = nb, $ NL = nl, $ NS = ns, $ OFFSET = headeroffset, $ POINTER_INFO = info, $ R_FID = r_fid, $ READ_PROCEDURE = readprocedures, $ /OPEN Page 9 of 12

10 Example Code for Writing Metadata to a File PRO write_envi_custom_file_embedded_header, data, BANDS = bands, $ BYTE_ORDER = byteorderout, DATA_TYPE = datatype, INTERLEAVE = interleave, $ LINES = lines, SAMPLES = samples, STORAGE_DATA_TYPE = storagetype, $ SCALE_FACTOR = scalefactor, MIN_VALUE = minvalue, _REF_ EXTRA = extra COMPILE_OPT IDL2, hidden filename = DIALOG_PICKFILE(/WRITE, /OVERWRITE_PROMPT) IF (STRLEN(filename) EQ 0) THEN RETURN OPENW, unit, filename, /GET_LUN byteorderout = BYTE(KEYWORD_SET(byteOrderOut)) headerstring = 'ENVIEmbeddedHDR' samples = LONG64(samples) lines = LONG64(lines) bands = LONG64(bands) interleaves = ['BSQ', 'BIL', 'BIP'] interleave = BYTE(WHERE(interleaves EQ STRUPCASE(interleave), count)) IF (count EQ 0) THEN RETURN ; Do the data conversions data = FIX(data, TYPE = datatype) IF (N_ELEMENTS(minValue) EQ 0) THEN minvalue = DOUBLE(0) data -= FIX(minValue, TYPE=dataType) minvalue = DOUBLE(minValue) IF (N_ELEMENTS(scaleFactor) EQ 0) THEN scalefactor = DOUBLE(1) data /= FIX(scaleFactor, TYPE=dataType) scalefactor = DOUBLE(scaleFactor) data = FIX(data, TYPE=storageType) storagetype = BYTE(storageType) description = $ 'This is an example of custom ENVI file with an embedded header.' + $ ' Created on ' + SYSTIME() descriptionlen = FIX(STRLEN(description)) Page 10 of 12

11 ; Do a byte swap if necessary IF (byteorderout) THEN BEGIN BYTEORDER, samples, lines, bands, scalefactor, minvalue, descriptionlen IF (SIZE(data, /TYPE) NE 1) THEN BYTEORDER, data IF ; Write file and close it. WRITEU, unit, byteorderout, headerstring, samples, lines, bands, $ interleave, scalefactor, minvalue, storagetype, descriptionlen, $ description, data FREE_LUN, unit Copyright Notice: ENVI is a registered trademark of Exelis Inc., a subsidiary of Harris Corporation. Page 11 of 12

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