This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
Hi Bernie, Sorry for the delay in replying. Recovering from my trip took longer than usual :-( re: > A binary file with a separate lat/lon file should work if I know how > the files are written. This would probably be the best format. OK. The McIDAS application you need to investigate is AXFORM. The output format of the files as explained by the online HELP is very simple: <in a McIDAS session> HELP AXFORM AXFORM - Converts a McIDAS Area file to ASCII or binary flat files AXFORM sarea file <keywords> Parameters: sarea | digital area number file | output file; maximum of 100 characters; specify as a file name or a fully qualified path (directory and file name); do not include an extension with the file name; see the Remarks Keywords: BANd= | band numbers for a multibanded sarea (def=first band) =ALL | all bands of sarea FLIp=YES | flip bytes; specify this keyword when the byte order on the destination system is the reverse of the source system, e.g., from a PC to a Unix workstation (def=NO) FORmat=I1 | output elements are 1 byte integers =I2 | output elements are 2 byte integers =I4 | output elements are 4 byte integers FTYpe=BIN | binary files (as specified in FORMAT keyword) (def) =ASC | ASCII text files (w/ 25I10 format) =BOTH | both file types MISs= | missing data value for .LAT/.LON extension files (def=65535 Hex FFFF) NAV=YES inc | produce .LAT/.LON data files with an element increment; these files contain LAT/LON stored as degrees*100 (2 bytes per element); the increment is the the number of data elements associated with each LAT/LON element (def=NO 1) UNIt= | calibration units of output files (def=cal units of sarea) =ALL | all calibration units defined by sarea Remarks: AXFORM creates a set of files which contain data from sarea. These files maybe ported to other non-McIDAS systems. Data is represented as 2 dimensional arrays of binary or ASCII fields whose dimensions are those of the original sarea lines/elements. An ASCII output text file documents the format of the output data files. It contains a listing for each of the data files generated. Output files are assigned unique extensions: .HDR (header file) - This file contains ASCII text describing sarea and the contents of the output data files. .nnn (data files) - These files contain binary data for a single calibration of a specific band. (nnn ranges from 001 to 999) .Ann (data files) - These files contain ASCII data for a single calibration of a specific band. (nn ranges from 01 to 99) .LAT (latitude file) - If NAV=YES, binary file contains a 2 dimensional array of latitudes corresponding to the elements within the output data files. .LON (longitude file) - If NAV=YES, binary file contains a 2 dimensional array of longitudes corresponding to the elements within the output data files. .ALT (latitude file) - If NAV=YES, ASCII file contains a 2 dimensional array of latitudes corresponding to the elements within the output data files. .ALN (longitude file) - If NAV=YES, ASCII file contains a 2 dimensional array of longitudes corresponding to the elements within the output data files. Defaults for the FORMAT keyword (assume FTYPE=BIN or BOTH): if: UNIT=BRIT then: FORMAT=I1 (1 byte integer) TEMP I2 (2 byte integer) RAD/RADN I4 (4 byte integer) ALB I2 (2 byte integer) REF/RERA I2 (2 byte integer) CNTS I2 (2 byte integer) RAW #bytes/element from sarea directory other I1 (1 byte integer) FORMATs smaller than the default size are NOT allowed. As you can see, you can output the data in binary or ASCII format. I assume you will want binary since an ASCII dump of a full image will be HUGE. re: > Also hdf5 files are OK. I also have an IDL netcdf file reader that I can > use. Sorry, McIDAS has no built-in capability to write to HDF5 files. By the way, I got a note from a friend in SSEC who is converting a different kind of image (the national 1 km composite base reflectivity radar product we make available by LDM/IDD transfer); remapping it to a rectilinear (Lat,Lon) projection; saving it in a GeoTIFF file (I mentioned this capability earlier); and making that image available through a web map service. You can see the results in: http://dcdbs.ssec.wisc.edu:8080/nexrcomp.html I mention this since I have a hunch that IDL might just support GeoTIFF. Cheers, Tom -- **************************************************************************** Unidata User Support UCAR Unidata Program (303) 497-8642 P.O. Box 3000 address@hidden Boulder, CO 80307 ---------------------------------------------------------------------------- Unidata HomePage http://www.unidata.ucar.edu **************************************************************************** Ticket Details =================== Ticket ID: SSN-755786 Department: Support McIDAS Priority: Normal Status: Closed