PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM MISSION_NAME = GALILEO SPACECRAFT_NAME = GALILEO_ORBITER OBJECT = TEXT PUBLICATION_DATE = 2003-03-31 NOTE = "AAREADME.TXT for Galileo SSI Calibration files to be used with the SSI Raw EDR CD-ROMs " END_OBJECT END Galileo Calibration CD-ROM 1. Introduction This data set has been generated by NASA's Galileo Project in order to distribute the processed calibration files generated by the Solid State Imaging (SSI) team to the scientists and later to the Planetary Data System (PDS). The data set consists of four types of processed calibration files (blemish, dark current, shutter offset and slope calibration files), as well as the technical documentation needed to better understand the SSI calibration process. Also included in this CD are missing templates, documents, and cumulative index files associated with the cruise (Phase 1) CD volumes GO_0002 - GO_0016. The calibration files are designed to be used with the Galileo SSI camera which acquires data in a digital raster-format containing 800 scan lines and 800 samples per scan line. Each picture element (pixel) in the two dimensional image array is represented as an 8-bit value between 0 and 255, proportional to the amount of light detected at that point (with 0 being the least amount of light and 255 being the greatest amount of light). The camera is equipped with seven color filters and a clear filter such that images taken through complementary filters can be combined during ground processing to produce color images. To make full scientific use of the image collection, the radiometric and geometric properties of the camera system should be understood. The files on this disc contain both a VICAR label and a detached PDS label. All PDS label formats and documentation are based on the Planetary Data System Data Preparation Workbook (D-7669, February 1995) (PDS1995) and the Planetary Science Data Dictionary (D-7116, Rev. D., JULY, 1996) (PDS1996). A brief description of the PDS label is described in the PDSLABEL.TXT file. The VICAR label is described in the VICAR2.TXT file. Both text files are located in the DOCUMENT directory. A new VICAR Procedure Definition File (PDF), GALSOS2.EXE, is included on the Galileo CD-ROM GO_0001 in the SOFTWARE directory. Please refer to the text file SOFTINFO.TXT in the same directory for more information. 2. Disc Format This CD-ROM disc has been formatted such that a variety of computer systems (e.g. IBM PC, Macintosh, Sun, VAX) may access the data. Specifically, the discs are formatted according to the ISO 9660 level 1 Interchange Standard, and file attributes are specified by Extended Attribute Records (XARs). There is one exception in the naming convention for calibration files and a few text files which is adhered to the ISO 9660 Level 2 Filename Standard. For computer software that fully supports XARs, access to the CD-ROM volume will be straightforward; the disc will appear to the user to be identical to a file system of directories, subdirectories and data files. Some computer systems that do not support XARs will ignore them; others will append the XAR to the beginning of the file, in which case the user must read past the first 512 bytes of the file. For further information, refer to the ISO 9660 Standard Document: RF# ISO 9660-1998, 15 April 1988. 3. CD-ROM Contents The files on this CD-ROM are organized in one top-level directory with several subdirectories. The following table shows the structure and contents of these directories. In the table, directory names are enclosed in square brackets ([]), upper-case letters indicate an actual directory or filename and lower-case letters indicate the general form of the directory file names. Top-level directory | |-AAREADME.TXT - A text file containing general information about the | data set (the file you are reading). | | |-ACRONYMS.TXT - A text file containing acronyms used throughout this CD. | |-ERRATA.TXT - Summary of errors and discrepancies in specific documents | contained on this volume. | |-VOLDESC.CAT - Volume Object describing this CD-ROM volume. | |-[CATALOG] - Directory containing files describing the data set, | | instrument, project, etc. | | | |- CATINFO.TXT - Describes the content of this directory | | | |- DATASET.CAT - Describes the Calibration data set | | | |- INST.CAT - Describes the SSI Instrument | | | |- INSTHOST.CAT - Describes the Galileo Orbiter Spacecraft | | | |- MISSION.CAT - Describes the Galileo Mission | | | |- PERSON.CAT - Describes contact information | | | |- REF.CAT - Includes all pertinent reference information | | | |- V_E1DS.CAT - Describes the data set from Venus, the Earth's | | Moon and the Earth during the 1990 encounters | | on volumes GO_0002 thru GO_0006 | |-[DOCUMENT] - Directory containing text files which describes the GLL | | process of generating calibration files and how to | | use the files to radiometrically correct images. | | | |- DOCINFO.TXT - Describes the contents of this directory | | | |- CALIB.TXT - Describes the processed calibration files | | | |- BIBLIOGRAPHY.HTM - HTML formatted bibliography of SSI Papers | | | |- BIBLIOGRAPHY.TXT - Text formatted bibliography of SSI Papers | | | |- CALRPT2.PDF - Calibration Report Part 2 in Adobe Acrobat | | PDF format (requires version 3.0 reader) | | Describes the camera calibration activities. | | | |- CALRPT2.LBL - PDS label of the Calibration Report Part 2. | | | |- CAL_SSD.PDF - Software Structural Design for the Calibration | | of GLL SSI Science Processing in Adobe Acrobat PDF | | format (requires version 3.0 reader) | | Describes software for generating SSI calibration | | files | | | |- CAL_SSD.LBL - PDS label of the Software Structural Design for | | the Calibration of GLL SSI Science Processing. | | | |- P1REDRSIS.PDF - Adobe Acrobat PDF of the Software Interface | | Specification for the Phase 1 Raw EDR | | (requires version 3.0 reader) | | | |- P1REDRSIS.LBL - PDS label of the Software Interface | | Specification for the Phase 1 Raw EDR | | | |- P1CDVOLSIS.PDF - Adobe Acrobat PDF of the Phase 1 Software | | Interface Specification for this volume | | (requires Version 3.0 reader) | | | |- P1CDVOLSIS.LBL - PDS label of the Phase 1 Software | | Interface Specification for this volume | | | |- BADDATA.TXT - Describes the binary Bad-Data Value header | | for the REDR Image Data (Not valid for | | calibration files). | | | |- PDSLABEL.TXT - Describes the PDS label. | | | |- VICAR2.TXT - Describes the VICAR2 image label. | |-[INDEX] - Directory containing an index file for searching for | | specific images. | | | |- INDXINFO.TXT - Describes the contents of the index directory. | | | |- IMGINDEX.TAB - A tabular file describing basic information about | | each calibration file on this volume. | | | |- IMGINDEX.LBL - A detached PDS label describing the contents of the | | index table. | | | |- CUMINDEX.TAB - A cumulative tabular file describing basic information | | about each image on this volume in the data set. | | | |- CUMINDEX.LBL - A detached PDS label describing the contents of the | | cumulative index table. | | | |- P1CUMINDEX.TAB - A cumulative tabular file describing basic | | information about each image on volumes GO_0002 | | thru GO_0016 data set. | | | |- P1CUMINDEX.LBL - A detached PDS label describing the contents of the | | P1CUMINDEX.TAB cumulative index table. | | |-[SOFTWARE] - Directory containing software and software information | | | |- SOFTINFO.TXT - Describes the software provided with the GO_0001 | | calibration CD. | | | |- GALSOS2.EXE - Vicar procedure that provides the capability to | | radiometrically correct Galileo SSI flight images. | |-[DARK] - Directory containing the Dark Current files. See the | | DATASET.CAT and CALIB.TXT files for more information on | | the files. | | | |-xxxx_DCyy.DAT;1 - where xxxx are the unique characteristics | | defining each individual Dark Current file and yy | | is the version number. | | | |-xxxx_DCyy.LBL;1 - The file containing the detached PDS label for | | the Dark Current file with the same name. | |-[SHUTTER] - Directory containing the Shutter Offset file. See the | | DATASET.CAT and CALIB.TXT files for more information on | | the file. | | | |-xxxx_SOyy.IMG;1 - where xxxx is the unique characteristics | | defining the Shutter Offset file and yy is | | the version number. | | | |-xxxx_SOyy.LBL;1 - The file containing the detached PDS label for | | the Shutter Offset file with the same name. | |-[BLEMISH] - Directory containing the Blemish Files. See the | | DATASET.CAT and CALIB.TXT files for more information on | | the file. | | | |-xxxx_BLMyy.IMG;1 - where xxxx are the unique characteristics | | defining each individual Blemish file and yy is | | the version number. | | | |-xxxx_BLMyy.LBL;1 - The file containing the detached PDS label for | | the Blemish file with the same name. | |-[SLOPE] - Directory containing the Slope Offset or Radiometric | | calibration files. See the DATASET.CAT and CALIB.TXT | | files for more information on the file. | | | |-xxxx_CALyy.DAT;1 - where xxxx are the unique characteristics | | defining each individual Slope Offset file and yy | | is the version number. | | | |-xxxx_CALyy.LBL;1 - The file containing the detached PDS label for | | the Slope Offset file with the same name. | 4. Formats The processed calibration data were generated at the Jet Propulsion Laboratory by the Multimission Image Processing Laboratory using procedures specifically developed or adapted for Galileo under the VICAR package. The files were generated on a VAX and are written in VAX compatible (LSByte first) format. Detached PDS labels are provided for each calibration file. See the DATASET.CAT file in the CATALOG directory for technical descriptions of each file. DARK CURRENT FILE FORMAT ------------------------- The Galileo Dark Current File is a binary file formatted as shown in Figure 1. A Dark Current is use to remove the level of dark current of the SSI Instrument which consist of a thermally generated charge which builds up on the CCD array and an electronic offset (pedestal). The dark-charge builds increases linearly with time and is pixel dependent, while the electronic offset drifts slowly with time and is constant for a given frame. Figure 1: Dark Current File Format Diagram ------------------------------------------------------ | VICAR LABEL | | | ------------------------------------------------------ | | | | | | | | | IMAGE DATA | | (pixels) | | | | | | | | | | | | | ------------------------------------------------------ A Dark Current file can be in Byte (8-bit) or Halfword (16-bit integer) format. Files in Halfword are usually several dark currents summed together and scaled to 128 times the dark current level to provide resolution to one-hundredth of a DN. Full frame mode dark currents are 800 lines by 800 samples. Summation mode dark currents are 400 lines by 400 samples. Each Dark Current file begins with a VICAR label, followed by the data. Each line in the data is a fixed record of either 400 pixels or 800 pixels. See the VICAR2.TXT located in the DOCUMENT directory. SHUTTER OFFSET FILE FORMAT --------------------------- The Galileo Shutter Offset File format is shown in Figure 2. Friction occurs in the shutter mechanism that reduces the actual exposure time of an image. It is important to accurately know the actual exposure time for good radiometric calibration. Thus, the shutter offset has been measured and calculated for each line of the CCD. Figure 2: Shutter Offset File Format Diagram ------------------------------------------------------ | VICAR LABEL | | | ------------------------------------------------------ | | | | | SHUTTER OFFSET DATA | | (800 values) | | | | | | | | | ------------------------------------------------------ Each Shutter Offset file begins with a VICAR label, followed by the data. The shutter-offset file consists of a single record in REAL*4 data format containing the shutter-offset (in milliseconds) for each image line (800 values). BLEMISH FILE FORMAT ------------------------- The Galileo Blemish File format is shown in Figure 3. Camera blemishes are pixels in the CCD array for which the output signal cannot be radiometrically corrected. Camera blemishes are removed as a factor from most of the computations by identifying and avoiding blemish areas in the analysis, or by cosmetically removing them via interpolation. Figure 3: Blemish File Format Diagram ------------------------------------------------------ | VICAR LABEL | | | ------------------------------------------------------ | | | | | BLEMISH DATA | | (4 values per blemish, 1 record) | | | | | | | | | ------------------------------------------------------ Each Blemish file begins with a VICAR label, followed by the data. The data is a single record of halfword (16-bit) data and defines blemishes by using vectors of the form (LINE,SAMP,CLASS,dfw) where LINE and SAMP are the picture coordinates where the blemish occur, CLASS describes the interpolation algorithm to be used to remove the blemish, and 'dfw' is the DN value at which the pixel saturates at full-well. The vectors are sorted first on LINE and then on SAMP. SLOPE OFFSET/RADIOMETRIC CALIBRATION FILE FORMAT ------------------------------------------------ The Galileo Slope Offset or Radiometric Calibration File format is shown in Figure 4. The radiometric file represents the slope terms of the inverse light-transfer function for each pixel at the lowest gain state. Figure 4: Slope Offset File Format Diagram ------------------------------------------------------ | VICAR LABEL | | | ------------------------------------------------------ | | | | | IMAGE DATA | | (pixels) | | | | | | | | | ------------------------------------------------------ Each Slope Offset file begins with a VICAR label, followed by the data. The radiometric file is an image with the same dimension as the SSI frame (800x800 for the full-frame format and 400x400 for the summation-mode frames). Each pixel in the file represents the slope term of the inverse light-transfer function for the lowest gain state. The values are stored in REAL*4 data format. 5. Calibration File Naming Conventions The calibration file naming scheme is very simple and it is based upon the information which makes a particular calibration file necessary. Since different camera aspects are altered by the different calibration files, different information about each of the files is needed to describe which files are necessary. The CALIB.TXT file should be consulted for further details. For example, since Dark Current files are not shuttered through the filters, they are not filter dependent. The camera aspects for each image are defined within the VICAR label or the PDS label by the following keywords: VICAR label PDS LABEL FILTER = 0 (clear) FILTER_NAME = CLEAR = 1 (green) = GREEN = 2 (red) = RED = 3 (violet) = VIOLET = 4 (IR-7560) = IR-7560 = 5 (IR-9680) = IR-9680 = 6 (IR-7270) = IR-7270 = 7 (IR-8890) = IR-8890 GAIN = 1 (400K) GAIN_MODE_ID = 400K = 2 (100K) = 100K = 3 (40K) = 40K = 4 (10K) = 10K RATE = 1 (2-1/3) FRAME_DURATION = 2.333 = 2 (8-2/3) = 8.667 = 3 (30-1/3) = 30.333 = 4 (60-1/3) = 60.667 FIBE = #### or MOFIBE =###### where # = 0 or 1 (OFF/ON) ON_CHIP_MOSAIC_FLAG = (Y/N) M = On-chip Mosaic 0 = Optical Navigation Frame LIGHT_FLOOD_STATE_FLAG = (OFF/ON) F = Flood light flag INVERTED_CLOCK_STATE = (OFF/ON) I = Invert clock flag BLEMISH_PROTECTION_FLAG = (ON/OFF) B = Blemish protection flag EXPOSURE_TYPE = (NORMAL/EXTENDED) E = Extended exposure flag READOUTMODE = (SAMPLE/CONTIGUOUS) READOUTMODE = (SAMPLE/CONTIGUOUS) 6. Text Files, PDS Labels, and Tabular Files All document files and detached label files contain a carriage return character (ASCII 13) and a line feed character (ASCII 10) at the end of each record. This allows the files to be read by the MacOS, DOS, Unix, and VMS operating systems. Tabular files are also described by a detached PDS label. The PDS label file has the same name as the data file it describes, with the extension .LBL; for example, the file IMGINDEX.TAB is accompanied by the detached label file IMGINDEX.LBL in the same directory. The detached PDS labels for calibration files contain information pertaining to the image. Tabular files are formatted so that they may be read directly into many database management systems on various computers. All fields are separated by commas, and character fields are enclosed in double quotation marks ("). Character fields are left justified, and numeric fields are right justified. The "start byte" and "bytes" values listed in the labels do not include the commas between fields or the quotation marks surrounding character fields. The records are of fixed length, and the last two bytes of each record contain the ASCII carriage return and line feed characters. This allows a table to be treated as a fixed length record file on computers that support this file type and as a normal text file on other computers. 7. CD-ROM Driver Software Patch Information As stated previously, for computer software that fully supports Extended Attribute Records (XARs), access to the CD-ROM volume will be straightforward. SunOS, SGI, and PC systems running NT require software patches described below to enable access to these CD-ROMs. o Sun Micro (SunOS 4.0.3 and later) Drive: Sun Microsystems Driver: SunOS sr.o driver Note: A patch must be made to SunOS before the Sun driver can access any CD-ROM files containing Extended Attribute Records, e.g. most of the files on this disc. A copy of this patch is available to Internet users via anonymous ftp from the 'space.mit.edu' server in the file named 'src/SunOS.4.x.CD-ROM.patch'. o Silicon Graphics IRIS Drive: SGI CD-ROM Drive Driver: SGI CD-ROM driver Note: A patch must be made to SGIOS before the SGI driver can access any CD-ROM files containing Extended Attribute Records, e.g. most of the files on this disc. A copy of this patch is available by calling the PDS user support. This patch is not needed for Version 4.0.5 and above. o PC (NT version 4) Note: Three 'service packs' must be installed before accessing most of the files on this disc. Copies are available via anonymous ftp from Microsoft at the following location: ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/nt40/ 8. For Additional Information Contact: For questions concerning this Galileo Calibration CD-ROM or access to the VICAR software: Amy Chen Jet Propulsion Laboratory MS 168-414 4800 Oak Grove Drive Pasadena, CA 91109 818-354-9043 Electronic mail address: Amy.C.Chen@jpl.nasa.gov For questions concerning this Galileo Calibration CD-ROM or access to the calibration files electronically via the Web: PDS - Imaging Node Jet Propulsion Laboratory MS 168-527 4800 Oak Grove Drive Pasadena, CA 91109 Electronic mail address: pds_imaging@charlotte.jpl.nasa.gov URL - http://www-pdsimage.jpl.nasa.gov/ For access to the ISIS software: United States Geological Survey, Flagstaff (USGS) URL - http://wwwflag.wr.usgs.gov/