JARtool Project
Clementine EDR Image Archive


Introduction

The Clementine EDR, (Experimental Data Record), Image Archive contains the collection of raw planetary images acquired by the Clementine mission. These data are pristine in the sense that they contain the artifacts and radiometric and geometric characteristics of unprocessed and uncorrected data. The only processing performed on the data is to organize and format the data according to the Planetary Data System (PDS) standards.

The Clementine images were compressed onboard the spacecraft using a space-hardened Matra chip. The compression enabled acquisition of many more observations of the Moon. The compression technique performed "lossy" compression using a Discrete Cosine Transform (DCT) algorithm. The images were kept in the compressed format when archived to reduce the total volume of the archive collection. Software is available on this volume to decompress the image data products.

The Clementine images are constructed according to the data object concepts developed by the PDS. By adopting the PDS formats, the Clementine images will be consistent in content and organization with the other planetary image collections that have been archived by the PDS.

Three documents, located in the directory, contain essential information about the mission and the data products contained on the archive. The file EDRSIS.ASC describes the organization, content, and format of the image data products. ARCSIS.ASC describes the volume organization and directory structure, and contains information about the contents of the ancillary data volumes that will follow this volume series. VOLINFO.TXT contains a description of the mission, mission phases and time lines, scientific payload, orbital dynamics, and initial scientific results.


Disk Format

The disk has been formatted so that a variety of computer systems (e.g. IBM/PC compatible, Macintosh, Sun) may access the data. Specifically, it is formatted according to the ISO 9660 level 1 Interchange Standard. For further information, refer to the ISO 9660 Standard Document: Reference Number ISO 9660-1988, 15 April 1988. The extended attribute records (XAR) supported by the ISO are not used in this volume series. The lack of XARs on a file only affects the VAX/VMS user community. It will be necessary for VAX/VMS users to use the VMS CONVERT utility to convert document and text files before they can be satisfactorily accessed. VAX/VMS users can contact the PDS Imaging Node for support of the Clementine EDR Archive.


File Formats

Each individual image acquired by the Clementine spacecraft is contained in its own file. An image file is made up of four parts: 1) a PDS label that describes the image, 2) an image histogram object containing statistics about the image, 3) a browse image object containing an uncompressed subsampled version of the image, and 4) the image object containing the compressed image. (For more information about the content of the image files, Click Here.)

All document files, detached label files, and tables are stored as ASCII stream-record files. In a stream-record file, records (lines of text) are separated by a carriage-return and line-feed character sequence. The / sequence marks the end-of-record and the start of a new record. For compatibility with VAX/VMS systems, each line is a fixed-length of 80 characters. Bytes 79 and 80 of each line contain the sequence. This organization works well for the Microsoft-DOS systems because the / sequence is identically used on these systems. On Macintosh systems, an end-of-record mark is simply a character. Macintosh text editors can read and access these files, but a special-character indicator will mark the "extraneous" character at the beginning of each line. On UNIX systems, an end- of-record mark is simply a character. UNIX text editors can read and access these files, but a special-character indicator will mark the "extraneous" character at the end of each line. File names with extension "TAB", "LBL", "ASC", "TXT", and "CAT" are formatted as ASCII stream-record files. In addition to the standard ASCII text file format used for documentation files, some documentation files may additionally exist in other forms to facilitate easy access to these files. File names with extension "DOC" are formatted as Microsoft Word Version 6.0 documents. File names with extension "EPS" are formatted as Encapsulated PostScript files.

Tabular files are formatted so that they may be read directly into many database management systems of 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 that describe the tabular files 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 / characters. This scheme 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.

PDS labels are object-oriented. The object to which the label refers (IMAGE, BROWSE_IMAGE, IMAGE_HISTOGRAM, TABLE, etc.) is denoted by a statement of the form:

^object = location

in which the carat character (^) indicates that the object starts at the given location. In an embedded label, the Clementine EDR image archive uses the form:

^object = n 

where "n" points to the starting byte location of the object. (The first byte in a file is designated as byte location 1.) For detached labels (labels existing in their own file) the object location is signified as:

^object = "file.nam"

In this form, the object of the label description exists in the file named "file.nam". For a description of the PDS object label specifications, consult JPL document D-7669.


Contacts for More Information

Additional information about the Clementine EDR Image Archive can be obtained by contacting:
The PDS Imaging Node
Branch of Astrogeology
United States Geological Survey
2255 North Gemini Drive
Flagstaff, AZ 86002
Internet e-mail: eeliason@sirius.wr.usgs.gov
Telephone: (602) 556-7113
The SPICE ancillary data files, produced by software provided by the PDS NAIF Node and used for the derivation of the geometry parameters, were the best available at the time the CD-ROM was produced. It is anticipated that improvements in some of these files will be made as further analysis is done. This could include correcting not-yet-discovered errors and filling in missing data. It is recommended that persons needing the most complete and accurate observation geometry contact NAIF for the latest Clementine SPICE files and, if the user does not already have it, the NAIF Toolkit software used to access these SPICE data. These SPICE files and the complete NAIF Toolkit are available on a companion disk within this PDS volume set. For additional information about the SPICE files used in the volume series, see Appendix I of the EDRSIS.DOC file. The NAIF Toolkit and up-to-date Clementine SPICE kernels can be acquired by contacting:
PDS NAIF Node
MS 301-125L
Jet Propulsion Laboratory
California Institute of Technology
4800 Oak Grove Drive
Pasadena, CA 91109
Internet e-mail: cacton@naif.jpl.nasa.gov
Telephone: (818) 354-3869

Errata, Disclaimer, And Anomalies

Although considerable care has gone into making this volume, errors are both possible and likely in the software, documentation, and data files. Users of the data are advised to exercise the same caution as they would when dealing with any other unknown data set. Reports of errors or difficulties would be appreciated. Please contact the PDS Imaging Node at the address shown in Section 5.

An ERRATA.TXT file will be maintained in the directory of each CD-ROM to report problems with files and software that reside on the CD-ROMs. Please refer to the ERRATA file in order to determine where the most current software and updated files are located.

Inconsistencies may exist between the histogram statistics found in the image histogram object and the actual image that is decompressed on your computer platform. Subtle differences in the floating point hardware among computer platforms may cause the Density Number (DN) values of a resulting decompressed image to be occasionally different (within 1 DN) than the decompressed image used to generate the image histogram object.

Data reviewers have reported confusion about several parameters that describe geometric information about the observations. The SUB_SPACECRAFT_LATITUDE, SUB_SPACECRAFT_LONGITUDE, SPACECRAFT_ALTITUDE, and SUB_SPACECRAFT_AZIMUTH parameters, found in the image index file (IMGINDX.TAB) and the image file labels, are referenced with respect to the central body which the spacecraft is orbiting, not necessarily the target of the observation. During the lunar mapping phase of the mission, the central body is the Moon. Thus, if the target is the Earth, the above listed parameters are referenced with respect to the Moon and not Earth.

Because the image decompression program, CLEMDCMP, requires a Discrete Cosine Transform (DCT) it may take several minutes to decompress an image on hardware platforms with slow processors. For example, in tests on a Macintosh IIci, the decompression takes approximately 4 minutes. In contrast, CLEMDCMP has been tested on hardware platforms with modern processors, such as an Intel 486DX2/66-MHz, and the decompression takes just several seconds.

The Clementine EDR image files use the PDS label constructs RECORD_TYPE = "UNK", and ^IMAGE = xxxxx to define the structure of the file. In addition, a "SFDU" label specification is not found at the beginning of a label. The labeled image files in this form are not supported by the current versions of IMDISP and IMAGE4PDS image display software that are widely distributed by the PDS. To display Clementine decompressed formatted files use the version of IMAGE and CLIMDISP programs that are supplied on this CD-ROM. The CLIMDISP and IMAGE software has been tested only on the Clementine data products. No attempt has been made to determine if these versions will work on any other PDS data product.

The xv system, provided on this CD-ROM, is an image display tool for UNIX systems. The xv software is unable to read Clementine PDS formatted files. To display Clementine images using 'xv', a user must first decompress the image using the CLEMDECMP software and output the file in either a GIF or TIFF format.

The Encapsulated PostScript files, ending with file extension EPS, were produced by Microsoft Word Version 6.0a. The MS Word documents were converted using the "write to PostScript file" option in the print command. The EPS files were tested and satisfactorily written on a SPARCprinter (Sun/UNIX system) and a HP LaserJet 4 (Microsoft windows environment). In addition the LaserWriter Font Utility on a Macintosh was able download the EPS files.


Acknowledgments

The design, production, replication, and distribution of the Clementine EDR Image Archive is the result of a cooperative effort between the US Naval Research Laboratory and NASA's Planetary Data System (PDS). The Applied Coherent Technology (ACT) Corporation, in contract to NRL, was responsible for the development of the processing system for the production of the archive and produced the archive data products for delivery to the PDS. ACT personnel additionally provided software tools that are included on the archive.

The Planetary Data System provided the funding for the mastering and replication of the archive for wide distribution to the science community. The PDS Imaging Node and Central Node supported the design effort, and developed software tools and ancillary data files that accompany the archive. The observation geometry parameters (such as range, latitude and longitude) that are found in the image index files (IMGINDX.TAB) and the PDS image labels were produced using software provided by the Navigation and Ancillary Information Facility (NAIF) at JPL.

The following individuals made substantial contributions to the successful completion of the Clementine EDR Image Archive:

Erick Malaret (ACT)
Luis Perez (ACT)
Howard Taylor (ACT)
Eric Eliason (PDS Imaging Node, US Geological Survey)
Chris Isbell (PDS Imaging Node, USGS)
Tracy Sucharski (PDS Imaging Node, USGS)
Janet Barrett (PDS Imaging Node, USGS)
Gail Woodward (PDS Central Node, Jet Propulsion Laboratory)
Chuck Acton (PDS NAIF Node, JPL)
Nat Bachman (PDS NAIF Node, JPL)
Mike Spencer (PDS NAIF Node, JPL)

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