IMAPP for Windows User's Manual (ver. 1.5R1)

Contents


Introduction

The International MODIS/AIRS Processing Package (IMAPP) is a suite of programs that lets anybody to process MODIS (and in future releases AIRS ) data from Level-0 to Level-1A and 1B products. The package has been derived at Space Science and Engineering Center (University of Wisconsin-Madison) from the operational MODIS processing software developed at NASA GSFC. It is distributed freely under the terms of GNU General Public License. Package description and source distribution can be found at the primary site at SSEC: http://cimss.ssec.wisc.edu/~gumley/IMAPP/IMAPP.html. The original IMAPP was designed to run on Unix. R&D center ScanEx has adopted it to run on Microsoft Windows platform. The last variant (let's call it IMAPPW) is hereafter described in this manual.

IMAPP can be used for entry levels processing of MODIS data level-0 received with direct broadcast (DB) station from Terra and Aqua satellites. This processing includes following operations

This paper tries to resolve a lack of  comprehensive IMAPP users's manual for those who don't like to drill down into a source code. It does not provide full coverage of the topic but focuses on the questions that are important for productive operation work. So we highly recommend you to read the SSEC's IMAPP page too. For description of processing algorithms, data formats and data interpretation please refer to documentation available from NASA.


Release notes (IMAPPW ver .1.5 )

ver 1.5R1
16 Jan 2004
This release contains calibration code patches that resolve problems with the nadir door state flags. The problems with Terra's MODIS might lead to the missing image data in MOD02 products.
ver. 1.5
12 Nov. 2003
Release is based on the IMAPP ver. 1.5.
  • Geolocation algorithm has been updated and GEO_parameters.dat files were updated for Terra and Aqua
  • New calibration tables are
       Terra: V 4.1.2.6 (April 15, 2003)
       Aqua: V 4.1.3.5 (April 29, 2003)
  • New features were added to EOSQView program: program window resize and image scrolling, time rule in absolute time values and possibility to cut a range of current PDS file into another one.
ver. 1.4
30 July 2003
 Release is based on the IMAPP ver. 1.4
  • First release to support Aqua data processing
ver 1.3
24 July 2002
Release is based on the IMAPP ver. 1.3. 
  • Main changes compared to the version 1.2 are related to calibration. IMAPP is updated to use V3 algorithms and calibration tables verion  3.0.0.
  • IMAPPW has preliminary support of processing MODIS stream from Aqua. There are several important notes concerning this feature
    • unpack works in the same way as for the Terra data
    • Aqua's MODIS stream does not contain ephemeris and attitude information, so geolocation can not be run in common mode using packet source. To resolve the problem IMAPPW introduces rough geolocation utilizing NORAD TLE orbit elements. Another way is to use GBAD package to prepare definitive data files. See Aqua geolocation notes for details.
    • Due to the lack of calibration tables for the Aqua at the moment of IMAPPW 1.3 release results of calibration are definitely wrong and can not be use for quantitative science. The only reason to do the calibration on Aqua files is the need to have MOD02*  formatted product files.

Look at the IMAPP revision history (at http://cimss.ssec.wisc.edu/~gumley/IMAPP/IMAPP.html) for the changes details.


Installation

Thinking to install IMAPP on Windows platform? Check the following requirements:

Other computer's properties have no crucial meaning.

To perform installation unzip the downloaded distribution and run setup.exe. Automated installation will place most necessary files at proper places under a directory you specified and perform all necessary settings. It is good idea to specify during installation a valid directory you plan to use for storing level-1A files (have at least several GB free there).  If you are installing the full package you are ready to run it (go to the next chapter). If you are installing distribution created more than 1-2 month ago you should also update two critical ancillary files (utcpole.dat and leapsec.dat)  before  you start using the IMAPP (see this manual further for how to find them).  In order to simplify run-time operation all ancillary data by default are placed in the \ancillary subdirectory of the installation root but this can be customized on file-per-file basis.

Please, note that the installation package does not include large ancillary files (namely Land-Sea mask and DEM) required for geolocation. These two file groups require about 0.8 and 1.8 GB disk space respectively. They are not mandatory for running IMAPPW programs but if one needs Land-Sea or height fields filled with proper data he has to download and install these file separately. See Geolocation parameters description further in this text for installation details.


Fast start

OK, so you've obtained a MODIS level-0 Production Data Set (PDS) with your EOS direct broadcast station. What? You don't have a a station yet? Why not consider an  EOScan station from ScanEx.

Lets you have acquired from space a PDS file with name foo.L0.pds (.pds extension is significant). Select it in the Windows Explorer, open a context menu and click on "IMAPP Unpack" item. A command prompt window will pop-up and the unpack.exe program will start processing your file to level-1A. Relax... Processing a full Terra overpass data (acquired during 10-15 min) takes about 5-10 min. depending on the speed your box can run. After the console window closes look into the L1a directory you have specified during installation and you will find level-1A file with name MOD01.AYYMMDDHHMM.hdf , where  YYMMDDHHMM denotes beginning time of the processed data.

In the same manner you can process L1A files further. First select "IMAPP geolocate" from the Explorer's context menu for MOD01.AYYMMDDHHMM.hdf  and after a certain time you will get a geolocation product file MOD03.AYYMMDDHHMM.hdf  in the same directory. More further use "IMAPP calibrate" menu item for MOD01.AYYMMDDHHMM.hdf  to start calibration process. At this step you have enough time to have a dinner... Full passage granule requires about half to one hour to be calibrated.

If you have got a set of files with names like MOD02*.AYYMMDDHHMM.hdf (this is a standard level-1B product) - you are lucky. Otherwise read this manual further and try to resolve the problem.


General issues

IMAPP for Windows includes four console 32-bit applications. This means that you have to use a command prompt window to use them. To abort execution during processing use Ctrl+C keyboard sequence. The primary way to specify input and output file names and other processing parameters is to set them as environment variables. This is by original design and are quite common for Unix gurus. For those who have not used command prompt for a long time we provide following example of sequence of commands

SET L0File=c:\eos\l0
SET L1aFile=c:\eos\l1a
unpack.exe

Windows port of the IMAPP introduces several improvements simplifying its usage. The first one is usage of imapp.ini file to store rarely changing (lets call them "static") parameters. This is a common  parameter=value file that can be edited as text. After initial installation records in this file should be valid and ready to use. This feature eliminates a need to employ global system environment or definition of many parameters during each session. If a parameter have been defined both in the INI file and environment - the last one have a precedence.

IMAPPW programs  are also able to accept a name of "primary" input file as a command line argument. Possibility to run IMAPP programs from Explorer's menu uses this feature. This feature significantly relies on the scheme of default name generation because all other parameters are substituted by default values or are read from the imapp.ini (or global system environment). In short this scheme works as follows

Meaning of  the most useful parameters are shortly described further in this manual. Each parameter definition is accompanied with a abbreviated list of possible methods to define this parameter. A method in the list have precedence over the subsequent ones. The following notation convention is used inside such lists:

E (Environment) the parameter can be defined via environment
I (INI) the parameter can be defined via imapp.ini file
C (Command line) the parameter can be specified in the command line 
+, - the parameter is mandatory (or not)

 Please, pay attention to the following note: all values representing directories must have a slash "\" at the end (e.g. "c:\imapp\log\").

Ancillary data

IMAPP programs use several types of ancillary data. With the installation package ( or separately) you can obtain most the data you need to run the processing. But it should be emphasized that some data can change between version or be time dependant and require periodic renewals. Current information on usage and availability of the ancillary data can be obtained from SSEC's or Scanex's IMAPP sites. Details on usage of some ancillary files are provided further side-by-side with the particular program description.

Note: ancillary file in ASCI text must be preserver in the original format (do not require Unix <-> DOS convertion) - so use binary mode while transferring them between platforms

Common parameters

Several run parameters are common to the most IMAPPW executables. They are summarized here:.

Parameter SMF_logs (E,I -)
specifies a directory where logging files will be placed. Due to SDP Toolkit's heritage IMAPP writes logs to tree files LogStatus, LogUser and LogReports. The last one is not used in the windows version. The primary log file that accepts messages is LogStatus. The new  messages are appended at the end of the file. It is good idea to keep it not very big with periodic examination and cleaning. If the parameter have not been specified log files are created in the current directory.
Parameter L1aMSG (E,I -)
specifies a directory that contains message texts to be written to the log. The message file are also come from the EOSDIS environment and have file names like PGS_* . Keep this issue in mind interpreting log messages (do not pay attention if you read message offering to report problems to the EOSDIS staff or to bring you computer to the room 123). If the message texts files are not available during execution only numeric identifiers of the messages are written to the logs.
Command line switches  -S and -s  (C)
These command line switches forces the programs to pause operation just before termination. After that user should press any key to close the program. This feature lets to avoid "flashing" console window when the program runs from the explorer's menu and terminates just after start. Low case switch (-s) forces pause only when the programs terminate with  errors occurred . Upper case switch (-S)  pauses the programs always. 

Level-0 to level-1A processing program (Unpack.exe)

Program unpack.exe reformats science and telemetry information from MODIS level-0 files into the level-1a files in a HDF format. Level-0 MODIS file contains a sequence of time-ordered CCSDS packets reconstructed from the satellite downlink stream. At EOSDIS such a file (strictly speaking a set of files) is called Production Data Set (PDS). We will use this term as well. At Dundee Satellite Receiving Station's site there is a page http://www.sat.dundee.ac.uk/modisformat.html that contains short introduction into the MODIS level-0 formats and links for further reading.

MODIS level-1A file is a standard EOSDIS science product identified as MOD01. This product is implemented in a HDF format and contains raw sensor data, on-board telemetry and created during processing quality information formatted as HDF objects (SDSs and attributes). This allows anybody to use general purpose programs to explore the data and get an MODIS earth view image on a screen.

Note for Aqua data processing: Orbital data from Aqua satellite come in separate data stream with APID 957( GBAD data stream). Receiving software by ScanEx stores  these packets in separate files with extension .gbd. If the unpack.exe finds during run a *.gbd file with the same name as the input PDS file has it tries to run GBAD processor on this file too. Output attitude and ephemeris files are produces for each output MOD01 granule with corresponding names (*.att and *.eph). This feature simplifies future processing with geolocate.exe.

Ancillary data

The following table lists ancillary data files used by unpack program along with according parameters specifying their location.

Ancillary file Parameter Notes
ENG_DATA_LIST EngDataList (E,I +) List of telemetry data fields with their position in the input and output streams
leapsec.dat LeapSec (E,I +) Leap seconds file. Required for accurate time conversions

Please, note that file leapsec.dat must be kept up-to-date. SDP Toolkit's support page (http://newsroom.gsfc.nasa.gov/sdptoolkit/leaputc.html) contains a link to the recent version and additional  comments concerning this file. Another source of the data is maintained at ftp://g0dps01u.ecs.nasa.gov/OTHR/

Execution parameters

Besides ancillary data location parameters unpack program uses following parameters

L0File (C,E, +)
name of the input level-0 file to be processed. Must be be defined throw a command line argument or environment variable.
L1aDir (E,I, -)
Default output folder. It is a directory where output files will be placed if their full path have not been specified
L1aFile (E -) 
filename of an output level-1A granule file. In case this parameter has not been defined its value will be created on the basis of  data imaging time in accordance with following format: MOD01.AYYMMDDhhmm.hdf. Where "MOD01" - product type prefix, "A" - denotes EOS-AM platform and may be something else in the future, YYMMDDhhmm - year-month-day-hour-min of the first scan in the granule. This format is not fully conforms to the EOSDIS standard filenames but is not so long. The filename can be specified without full path. In this case the file will be stored in the directory given by the L1aDir parameter. If the last is not set then the output will be placed in the current directory.
FirstGranStart and LastGranStop (E,-) 
These two optional parameters let to define a data stream time subrange to be processed. These parameters should be both set, or both not set. If they are set only data in time range from FirstGranStart to LastGranStop will be used for processing. If they are not set all time coverage of the input PDS file will be used. These time should be specified in the following format: "YYYY-MM-DDThh:mm:ss.ssZ"  - letters T and Z are significant (this is so called CCSDS ASCII Time Code A format)
StartAfter (E,-)
Time in seconds to skip data from the beginning of the input PDS file.
StopBefore (E,-)
Time in seconds to stop processing at before the end of  the input PDS file. This and the previous parameters provide possibility to define a subset of the data stream to be processes in terms of relative time defined in seconds from the ends. This is an alternative method to specifying absolute time range with help of  FirstGranStart/LastGranStop pair.
GranTimeLength (E,I -)
duration (in seconds) of output granules to be created. By default all input data are processed into one level-1A file. Using this parameter you can cut the data into pieces of predefined length.

Geolocation program (geolocate.exe)

This program performs a geolocation processing of MODIS data and outputs an HDF file containing arrays of latitude/longitude and imaging angles for each 1km pixel. Output file has EOS product identifier MOD03.

IMAPP can calculate geolocation fields using satellite ephemeris and  attitude information contained in the Direct Broadcast downlink stream. This feature lets to perform processing just after the data reception. IMAPP can also use definitive ephemeris/attitude ancillary files as the DAAC's operational software does to achieve more precise geolocation. The main disadvantage of the definitive data is that it may be available only after a certain time (1-2 days) after imaging.

Definitive data are provided now for public by SSEC at ftp://terra.ssec.wisc.edu/pub/terra/ephemeris/ . Attitude and ephemeris data files are provided separately and are organized by time. In order to use definitive data for geolocation you must have both attitude and ephemeris files for the appropriate time range.  The files have names like "AM1ATTNF#001030720012000000000000". In order to decode it pay attention to the fields in bold. They mean: AM1 - Terra platform, ATT (or EPH) - attitude or ephemeris data, 03 -month, 07 -day, 2001- year, 20 - hour of start of the data. Most files covers time range of 2 hours. Please, note that authors of this manual are not responsible for mentioned definitive data source and information you have just read may be out-of-date.

Ancillary data

Ancillary file Parameter Notes
leapsec.dat LeapSec (E,I +) Leap seconds file (used by unpack.exe too)
GEO_parameters.dat GeoParms (E,I +) MODIS sensor geometry calibration parameters (Terra) 
aqua/GEO_parameters.dat AquaGeoParms (I) MODIS sensor geometry calibration parameters (Aqua) 
utcpole.dat UTCpole (E,I +) Earth motion file
de2000.eos PlanetEphem (E,I+) Space bodies ephemeris are in use for Sun and Moon position calculation. This is compiled to binary form from de200.dat
lwm1_n*x* LandSea (E,I -) Land-sea mask data. This parameter is a list of all the files separated with ";". Full file path must be specified at least for the first item in this list.
dem30ARC_*_imapp.hdf DEMfiles (E,I -) 1km DEM files. This parameter is a list of all the files separated with ";". Full file path must be specified at least for the first item in this list.

Utcpole.dat is a Earth Motion file containing a record of the Earth's variable rotation with respect to Coordinated Universal Time (UTC). IMAPP requires this information for accurate transformations between inertial and Earth-fixed coordinates. For accurate geolocation the file requires periodic (about once per moth) updates. Recent version and comments regarding this file are available from http://newsroom.gsfc.nasa.gov/sdptoolkit/leaputc.html (or  ftp://g0dps01u.ecs.nasa.gov/OTHR  or  ftp://oceans.gsfc.nasa.gov/COMMON/).

Land-sea mask (files lwm**) are required because standard EOS geolocation product (MOD03) should contain a piece of this data inside. The whole worldwide coverage is divided into six tiles stored in separate files. IMAPPW distribution does not include these files. They may be downloaded separately from http://www.scanex.ru/eosdb/imapp.htm or found inside geolocate.tar.gz file from SSEC's original source distribution. So you should fetch and decompress them (each will take about 150 MB) in the ancillary data directory before starting  work. To make the geolocate.exe use these files and process Land-Sea mask you have to uncomment (remove starting ";" sign) or add the LandSea parameter in the imapp.ini and point it to the files you have installed.  IMAPPW can also run without this files if you do not require land-sea mask in the product files. 

Digital elevation model (DEM) files are required for terrain correction and writing valid height fields in the product files. Total DEM files volume is about 1.8GB. These files are also optional, may be downloaded from ftp://origin.ssec.wisc.edu/pub/IMAPP/MODIS/Level-1/ and should be pointed by DEMfiles parameter to be used during geolocation process.

Parameters

Geolocation program utilizes only two additional parameters which specify names for input and output files.

L1aFile (C,E,+)
name of input level-1A (MOD01)  file to be processed. Full path must be specified.
GeoFile (E - ) 
name of the output geolocation file (MOD03). If this parameter has not been set the file gets default name and is placed in the same directory where the input file lies. Default geolocation file naming convention is: 
1. if input file name contains a substring "MOD01." it will be replaced with "MOD03"
2. otherwise a prefix "MOD03." is simply appended
SC_ATTIT (I,E,-)
Full name of the definitive attitude data file(s). Several files may be given separated with ";".
SC_EPHEM (i,E,-)
Full name of the definitive ephemeris data file(s). Several files may be given separated with ";". In order to use definitive data for geolocation BOTH SC_ATTIT  and SC_EPHEM parameters must be specified at once.
TLEPath (i,E-)
File mask (with the full path) for the NORAD TLE files (e.g. "c:\tle\*.tle" - declares to use all files in c:\tle with extension tle). The program checks all suitable files and automatically selects a TLE orbital elements set which is closest to the time of data being processed. So user may set this parameter one and only gather TLE files  in the specified directory.  Program reports the age of the selected set. Current TLE files for Terra and Aqua satellites may be obtained from www.celestrak.com
If this parameter is defined geolocate will ignore data from the MODIS packets and will use SGP4 model to calculate position and velocity of the satellite while assuming that all the attitude angles are zeros (real typical values are of order 10-5  that gives quite small geolocation errors). For TLE set age of 1-2 days geolocation error may be about several kilometers and may significantly increase with further ageing. So users are advised to keep orbital data files up to date.

Aqua geolocation notes 

MODIS data stream from the Aqua satellite does not contain ephemeris and attitude information. This means that geolocate.exe may not be used in usual mode utilizing MOD01 input as the only data source. Three possible ways out are to...


Calibration program (calibrate.exe)

The last of three main IMAPP programs performs systematic calibration of MODIS earth view data from raw device counts to absolute radiances. As a result standard MOD02 product is generated. Calibration algorithms are described in the book "MODIS Level 1B Algorithm Theoretical Basis Document (ATDB MOD01)". The output product consists of 4 separate files:

MOD02QKM  Earth view calibrated data at 250m resolution, contains the 250m bands only 
MOD02HKM Earth view calibrated data at 500m resolution, contains the 500m bands (3-7). It also contains the 250m bands resampled to 500m.
MOD021KM Earth view at 1km resolution, contains the 1km bands split into two categories: Reflective (8 -19, 26) and Emissive (20-36 except 26). It also contains the 250m and 500m bands resampled to 1km.
MOD02OBC On-board calibrator data extracted from level-1A

As an input the calibration process utilizes both level-1A and geolocation files generated at the previous processing steps.

Ancillary data

Calibration process requires a set of  look-up tables (LUT) that are generated by MODIS Characterization Support Team (MCST) from pre-flight and operation time measurements. All required LUTs are supplied with the IMAPP installation package. Parameters referring following  calibration Lookup tables are also repeated for Aqua version (with Aqua... prefix, corresponding files are stored in ./ancillary/Aqua subfolder)

Ancillary file Parameter Notes
Reflective_Lookup_tables_file ReflTable (E,I+) Calibration LUTs for reflective bands (1-19,26)
Emissive_Lookup_Tables_file EmisTable (E,I +) Calibration LUTs for emissive bands (20-25,27-36)
QA_Lookup_TAbles_file QATable (E,I +)  

Parameters

L1aFile (C,E+)
filename (with full path) of input level-1A (MOD01) granule to be processed. MUST be defined either in the command line or throw environmental variable
GeoFile (E - ) 
full name of a input geolocation (MOD03) file for the granule to be processed. This input file required for processing. If the parameter has not  been set the program tries to use file with name obtained from the L1A filename with replacing "MOD01" with "MOD03".

Following parameters specifies location of output files. If they do not fully defines all files placement common default naming scheme will be used. That is output files will have names with "MOD02**" in place of  "MOD01" in input L1a filename.

L1B_EV_250M (E -) - full filename for MOD02QKM product

L1B_EV_500M (E -) - full filename for MOD02QKM product

L1B_EV_1000M (E -) - full filename for MOD02QKM product

L1B_OBC_FILE  (E -) - full filename for MOD02OBC product

L1bFile (E -)

a template of the output filenames that may help to specify all previous names at once. All four names are generated from this template with addition of product suffixes. If you set this parameter you have not to set L1B_* ones. For example if L1bFile was set to "c:\mod01\12345" then you will get "c:\mod01\12345.MOD02QKM.hdf" etc.


EOS QuickView

EOS QuickView (EOSQV) program was developed as an add-on to the basic IMAPP programs in order to simplify handling of level-0 data sets. This program incorporates a lot of level-0 and level-1A code and generally provides the same functionality  as the unpack.exe does. But it adds a graphical user interface which helps to do the most tasks in point-and-click manner. EOS QuickView also makes it possible to... 

EOS QuickView is installed together with other IMAPPW stuff and shares with the unpack.exe parameters defined in the imapp.ini file. 

Customization

While beeing using EOSQV for the first time you should check validity of working parameters. This can be done with dialogs callable though the Options menu item.

General options dialog

This dialog box lets to define generic processing parameters. Many of them are the same as for the unpack.exe  and are shared between the programs. This parameters are stored in the imapp.ini file. Common parameters are stored under the [IMAPP] section and parameters used by the  EOSQV only are defined in the [EOSQV] section. So take into account that modification of the common parameters via EOS QuickView GUI may influence the behavior of the unpack.exe.

Short descriptions of the fields available in the General options dialog follow. If the parameter is common to EOSQV and unpack.exe its name is given in parenthesis. Parameters that have a value of file or directory name may be specified either with directly typing the value in the edit box or selecting them with help of a standard dialog boxes that callable via "tree point" buttons.

Leapsec.dat (LeapSec) 
fully qualified filename of the Leap seconds file. Supplied file has name leapsec.dat and is installed in the ./ancillary subdirectory.
Eng. data list (EngDataList)
List of telemetry data fields. Default file name ENG_DATA_LIST.
Log directory (SMF_logs) 
directory where the processing log will be stored. Note again that all parameters specifying directories must have "\" at the end.
Message Files (L1aMSG)
directory that contains a set  of logging message files
BMP export
directory where output BMP files will be stored by default. Generally you will be always asked to provide full output filename. But if you are going to often use the same place for output bitmaps it is a good idea to specify this place here.
L1 export (L1aDir)
default directory for level-1A output files

QuickLook options

This dialog is callable via Options|Quicklook... menu item and provides possibility to customize quicklook generation parameters.

EOSQV always generates a quicklook from one MODIS band and draws it using a gray-scale palette. The band that will be used for quicklooks may be selected from the Band combo box. Note that the reflective (1- 19) MODIS bands are not available during operation in the night mode. If a reflective band is in use this will lead to the night mode part of the quicklook picture to be filled with white. So if you are often have a night mode data you'd better to use one of the emissive bands for preview. Otherwise you may use any band that you will find to be the best looking. For example bands 17 and 18 of Terra's MODIS  look quite nice.

You can also define an integer scale at which quicklooks will be created. There is a Scale field for this purpose. Current EOSQV version does not support scrolling in the quicklook window. So you should find a scale value that will give quicklook size appropriate for your monitor settings. For screen resolution 1024x786 the scale value of 8 was found to be suitable in the most cases.

Due to the MODIS scanner performs 12-bit quantization a some sort of  pixel value transformation must be supplied during conversion to a viewable 8-bit gray image. EOSQV utilizes the simplest method - linear stretch of 4096 levels into 256. Because the real earth view data usually occupy only a part of the available dynamic range this method often gives unacceptable pictures. The EOS QuickView offers two simple ways to solve this problem. The first one is to postcorrect an quicklook picture to enhance it (see Image correction dialog description later in this text). The second option is to adjust parameters of the level reduction conversion itself. The last method can be switched on/off with the Histogram stretch checkbox. If the histogram stretch is used the conversion procedure stretches to 256 levels only a part of  input image dynamic range that contains 98% of  the histogram. This provides automatic conversion parameters adjustment to the current image. But this method does not always provides good results due to the following reasons. Currently a one-pass procedure is used for the quicklook generation and in order to gather the histogram it utilizes only the first data scan  which has not less then 1/3 valid image pixels. Sometimes this leads to poor estimation of the full-image histogram in case when the image has significantly varying brightness (e.g. night at the north). So this feature should be considered as experimental and may be changed in future releases.

Image correction dialog

This dialog gives possibility to adjust quicklook viewing parameters. The dialog provides two sliders that control imaging parameters which behave like common brightness and contrast. You can play with this parameters in order to get an acceptable picture. Dragging the sliders up increases brightness and contrast of the quicklook and vise versa. The Reset button returns parameters to the "central" values which correspond to 1-to-1 image levels conversion (i.e. no level adjustment). All parameter changes are applied to the currently visible quicklook immediately and will be stored for future use after the OK button click. This dialog may be used even during quicklook generation process.

PDS File operations

There are two ways to open an input level-0 file (PDS) in the EOS QuickView. The first (quick) way may be useful if you know the PDS's filename and are going to create and view the quicklook for the whole data set. In this case the menu command File | Open PDS... may be used. After selection of the input PDS file via a standard file open dialog process of  a quicklook generation will be started. At this time the application window's size will be adjusted to the expected size of the quicklook and a time rule will be drawn at the right side of the window. The time rule may be quite useful while dealing with level-0 because the most of tasks with such data are performed in terms of start and end times. The rule contains a mark and absolute value for the first full minute time and marks with time offsets relative to this point. 

Progress of the processing is indicated in a status bar at the bottom of the program window. The quicklook is being drawn to the window during operation. This also gives a visual hint on the process completeness. Quicklook generation can be interrupted at any time by pressing the ESC button. Regardless of full quicklook was generated or not the PDS file will be treated as open and will become a current opened file.

The second way to select a PDS file  is to use a Select PDS dialog available trough File|List PDSs.... menu item. This dialog contains a list of PDS files contained in the specified directory. Besides filenames this list contains also file sizes and start and end times. The directory to be searched for the PDS files may be defined in the edit box at the top of the dialog. After selecting a file in the list the are three operation that can be initiated on this file:

Data export

The main function of the EOSQV is an export of a selected range of MODIS level-0 data into a level-1A. The time range of data to be exported can be defined interactively by selecting a region on the quicklook image with mouse. Click and hold the left mouse button and drag the rectangle selection box over the image. Refer to the time rule at the right while selecting the range.

Export operation can be started directly from the Select PDS dialog or with the File|Export... menu command after the PDS file has been opened. As the first step the Export parameters dialog appears in order to ask the user for export parameters. At the top of the dialog the name of the current PDS file is shown. Then a button follows which defines currently selected time range in form "Start Time - End Time = Number Of Scans". This button also lets to overwrite the time region to process. The dialog contains also two controls groups for parameters related to BMP and level-1A exports accordingly. Set the checkbox near the appropriate group caption to select this type of export to be performed. Both export types can be defined simultaneously and done during single processing pass. 

For the BMP export operation the following parameters can be defined.

Output
name of the output BMP file. If there are more then one band have been selected for export this field will be used as a filename template. In this case produced files will have the postfix "_bBandNo" (where BandNo denotes numeric band number) appended .
Bands
set of bands to be written to the output BMP files. Please note that not spectral range numbers but storage ordinal number of bands are here in use. The MODIS has two doubled bands (13lo and 13hi, 14lo,14hi). That means that bands numbers greater then 14 will be shifted by 2. For example, 12 denotes 12th MODIS band, 14 = 13hi MODIS band and 38 = 36th MODIS band. To define more then one band separate them with commas. To define a continuous range of bands you may define only the first and last ones with a dash in between. For example, string "1,2,8-9" defines following set of bands {1,2,8,9,10}. Even all bands may be specified at once with "1-38".
Scale
integer pixel subsampling scale. This number is related to the 250m pixel size regardless which bands are processed. This gives possibility to obtain the same size bitmaps from bands with different resolution. So if scale 1 is defined all written images will have nominal resolution 250 m per pixel. Scale value 4 will give bitmaps with resolution 1 km, and so on.
Scan geometry correction 
if this checkbox is checked the simple systematic correction of "bow-tie" image scan distortions will be done during BMP export.

For the level-1A export there is only one main parameter that must be defined - output file name. By default export operation is performed by the EOSQV itself. As an option you can set the Run as separate process checkbox and execute unpack.exe with specified parameters in a separate console window .


L0 file tool (L0_scan.exe)

IMAPP contains an additional tool L0_scan.exe that helps to check quality of input PDS files and get general information on its content. This program takes two command line arguments: name of a PDS file to gather information off and name of output text file that will contain the program output. The second parameter is optional and if it is omitted all the output will be directed to the console window. The tool reports following information on the PDS file:

The following is an example of output of the L0_scan.exe  for PDS file containing one occurrence of the packet stream time inversion near the beginning :

input filename: f:\eos\l0\10090757.pds

------------------- Messages ----------------
1%
Warning: out-of-time-order packet, utc: 2000-10-09T08:01:00.797330Z,
time: 245232068.074309, last_time: 245234165.226363
100%
------------------- Summary ------------------
n_packets: 1335423
n_day_pkts: 1333655
n_night_pkts: 0
n_scans: 445
start_time: 2000-10-09T08:00:48.980222Z
stop_time: 2000-10-09T08:11:44.830111Z 

Frequently Asked Questions

Are the files produced with IMAPP  have the same format as the files that may be acquired from the EOSDIS DAACs?
Strictly speaking - no. They have nearly identical set of SDSs and Vtables, but differ in the way  some global attributes are stored. Probably, the most serious consequence of this is that files produced with the IMAPP are not in HDF EOS format. If you work with MODIS data from EOSDIS but experience problems opening IMAPP generated files you may try to use additional tool imapp2daac which makes product files to be valid HDF-EOS and write several additional DAAC-style metadata  fields. The tool is available from http://eostation.scanex.ru/software.html.
 
Can I process MOD01 files obtain from EOS DAAC ?
Yes you can. You may do it in usual manner, but generated output files will miss several metadata fields of minor importance.
 
I want the MOD01 and subsequent products to be created in another directory.
Change the L1Dir value in the imapp.ini file to point to the directory you need.
 
The geolocation process terminates just after the start with message "Error opening HDF file "input MOD01 file name"".
Geolocation program must have read and write access to the input MOD01 file. Check carefully if you have write permissions for the input file and it does not have READ ONLY attribute set. Note that the READ ONLY attribute is set on if you have just copied the file from the CD-ROM. Due to the same reason the MOD01 input can not be used directly from read-only media. 
 
The geolocation process takes many hours. Is anything wrong ?
Slow geolocation in IMAPP versions prior to v1.2r1 was caused by outdated utcpole.dat file. Starting with version 1.2r1  IMAPPW accepts old utcpole.dat. If this file does not contain records for the required date the zero values will be used. This will give geolocation error as order as several tens meters. That is quite small error for MODIS data for most applications. Those who require best geolocation quality should keep the ancillary data up-to-date.
 
Land-Sea mask or Height field in generated product files are filled with dummy values. But I need actual values in these fields.
Read carefully the chapter on geolocation program in this manual. You have to obtain and decompress all appropriate ancillary files (LSM and DEM file sets require more then 2GB disk space) and set LandSea (DEMfiles) parameter to point to these files. All files in the set must be present for the geolocation to work properly.
 
MOD01 files produced with IMAPPW can not be processed further by original IMAPP ? What the problem ?
There is forced and an annoying mismatch between names of one attribute in the product files generated by original and windows versions. Original IMAPP writes attribute "Number of scans", but IMAPPW writes it as "Number of Scans" strictly following the format specification and DAAC produced samples. Due to the HDF library is case-sensitive this leads to misunderstanding. If you have a source code distribution of IMAPP you may simply replace Number of scans by Number of Scans everywhere to resolve the problem.
 
Where can I find descriptions of the MODIS calibration algorithms and MOD02 data product ?
Check the following sources:
 1. " The MODIS Level 1b Algorithm Theoretical Basis Document ATBD-MOD-01"  (can be fetched from http://eospso.gsfc.nasa.gov/atbd/modistables.html).
 2. "MODIS Level 1B Product Userís Guide"
 3. Look at the MCST's site (http://www.mcst.ssai.biz/mcstweb/) for current information
 
Does IMAPP support processing data from Aqua satellite ?
Starting from  version 1.3 IMAPPW provides full support for processing Aqua data.
 
Help, suddenly Imapp geolocate and Calibrate items have disappeared from the explorer's context menu for HDF files
Installation (or uninstallation) of some other programmes working with HDF files may disturb registry settings. The same may happen if you have reinstall the operating system or damaged thr registry in some manner. To restore IMAPP related setting you may run IMAPPW installation program again or register OLE server in imapputil.dll (i.e. run this file with regsvr32.exe)
 
Where can I obtain MODIS data for my work ?
If you need MODIS data regularly you may install your own EOS DB station and acquire MODIS data directly to your computer.
Low cost DB stations are offered by R&D center ScanEx (look at http://www.scanex.ru/). 
 

Additional links

Several interesting sites not mentioned before