Viking Lander EDR Image Archive CD-ROM

Table of Contents

  1. Introduction
  2. CD-ROM Format
  3. File Formats
  4. Image Display
  5. CD-ROM Contents
  6. Image Browser
  7. Whom to Contact for Information
  8. Cognizant Persons

Note that some of the links in this document require Internet access.

1. Introduction

This CD-ROM is one of two CD-ROMs that contain Viking Lander EDR (Experiment Data Record) images and ancillary files. Images returned by Viking Lander 1 are archived on volume 1 of this two-volume set, whereas Viking Lander 2 images are archived on volume 2. Each volume also contains a complete set of documentation and errata files that describe the archive and EDR images. Each EDR image has an attached PDS label that describes the file structure and instrument parameters used for that image.

EDR products archived on this volume are copies of images released by the Viking Project. The data were recovered from the original 9-track tapes made for the Lander imaging team. The file format, however, has been converted from the original VICAR format to a PDS format. Errors and anomalies in reading the original tapes are noted where detected. Supporting documentation and labels conform to the Planetary Data System (PDS) Standards, Version 3.2, Jet Propulsion Laboratory (JPL) document JPL D-7669 Part 2 (7/24/1995) and the Planetary Science Data Dictionary, JPL Doc. JPL D-7116, Rev D (7/15/96).

2. CD-ROM Format

The CD-ROM has been formatted so that a variety of computer systems (e.g., PC, Macintosh, and 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: RF# ISO 9660-1988, April 15, 1988.

This CD-ROM does not contain any Extended Attribute Records (XAR). Thus, VAX/VMS users may have some problems accessing files on this volume.

3. File Formats

Each PDS image file on this volume is stored with a fixed length record format. There is an attached PDS label at the beginning of each image file that describes the content and format of the image. An image histogram is stored in the file following the label. The image data follows the histogram. If the PDS label size is not an exact multiple of the file record length, then padding is added after the end of the PDS label. The histogram is also padded if necessary. Thus, both the histogram and the image object always start on a record boundary. A more detailed specification of the image file format is given in the CDVOLSIS.TXT file in the DOCUMENT directory.

All document, detached label, and HTML files are stream format files, with a carriage return (ASCII 13) and a line feed character (ASCII 10) at the end of the record. This allows the files to be read by the MacOS, DOS, Unix, and VMS operating systems. All tabular files are described by PDS labels, which are detached label files having the same name as the data files they describe, with the extension .LBL. For example, the file CUMINDEX.TAB is accompanied by the detached label file CUMINDEX.LBL in the same directory.

Tabular files are formatted so that they may be read directly into many database management systems (DBMS) or spreadsheet programs 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 a PDS label 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.

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

^object = location

in which the carat character (^, also called a pointer in this context) indicates that the object starts at the given location. For an object in the same file as the label, the location is an integer representing the starting record number of the object (the first record in the file is record 1). For an object located outside the label file, the location denotes the name of the file containing the object, along with the starting record or byte number. For example:

^IMAGE = ("C102.IMG",3)

indicates that the IMAGE object begins at record 3 of the file C102.IMG, in the same directory as the detached label file. Below is a list of the possible formats that use the ^object keyword.

^object = n
^object = n
^object = ("filename.ext",n)
^object = ("[dirlist]filename.ext",n)
^object = ("filename.ext",n<BYTES>)
^object = ("[dirlist]filename.ext",n<BYTES>)

where n starting record or byte number of the object, counting from beginning of the file (record 1, byte 1); default is record number.
<BYTES> indicates that number given is in units of bytes.
filename upper-case file name.
ext upper-case file extension.
dirlist period-delimited path-list of parent directories, in upper case, that specifies the object file directory (used only when the object is not in the same directory as the label file).

4. Image Display

The PDS provides software for displaying PDS format images on a variety of computer platforms. The application program for image display is called NASAView, which has versions for SUN, Macintosh, and PC platforms. For some computer platforms, there is a NASAView version that will work as a Web Browser helper application.

It is the intent of PDS to distribute NASAView through its Web and FTP sites. Consult the PDS Web site for the status of NASAView in terms of its capabilities and availability. The Web addresses for the PDS Web site and software page:

PDS Home Page:
PDS Software Page:

5. CD-ROM Contents

Files on this CD-ROM are organized into a series of subdirectories below the top-level directory. The following table shows the structure and content of these directories. In the table, directory names are enclosed in square brackets ( [ ] ).

Top-level directory
|- AAREADME.TXT The file you are reading.
|- AAREADME.HTM Hypertext version of AAREADME.TXT file.
|- ERRATA.TXT List of comments and errors for this volume set.
|- VOLDESC.CAT Description of the contents of this CD-ROM volume in PDS label format.
|- [CATALOG] Directory containing PDS catalog information about the Viking Lander image EDR data set.
|- |- CATINFO.TXT Description of files in the CATALOG directory.
|- |- <files>.CAT Files describing the Viking mission, spacecraft, instrument, and the EDR data set.
|- [DOCUMENT] Directory containing document files.
|- |- DOCINFO.TXT Description of files in DOCUMENT directory.
|- |- CDVOLSIS.TXT Software Interface Specification (SIS) document for the CD-ROM.
|- |- CDVOLSIS.HTM Hypertext version of the CDVOLSIS.TXT document.
|- |- VOLINFO.TXT Overview of the mission, imaging instrument, and the archiving process.
|- |- VOLINFO.HTM Hypertext version of the VOLINFO.TXT document.
|- [INDEX] Directory containing index files.
|- |- INDXINFO.TXT Description of files in the INDEX directory.
|- |- CUMINDEX.TAB Cumulative index in tabular format.
|- |- INDEX.TAB Volume index in tabular format.
|- |- INDEX.LBL PDS label for INDEX.TAB.
|- [CALIB] Directory containing calibration files.
|- |- CALINFO.TXT Description of radiometric calibration files and procedures.
|- |- CALINFO.HTM Hypertext version of CALINFO.TXT document.
|- |- <files> Calibration data files.
|- [GEOM] Directory containing geometry files.
|- |- GEOMINFO.TXT Description of geometry files and procedures.
|- |- GEOMINFO.HTM Hypertext version of GEOMINFO.TXT document.
|- |- <files> Lander and camera geometry files.
|- [BROWSE] Directory containing the image browser.
|- |- INDEX.HTM Top page for browser.
|- |- [HTML] Directory with subdirectories for HTML pages.
|- |- |- [NXXX] Directories with HTML files for browse images in sequence NXXX.
|- |- [IMAGE] Directory with subdirectories for browse images.
|- |- |- [NXXX] Directories for browse images.
|- |- <files> Other image browser files.
|- [NXXX] Directories containing PDS format image files for series NXXX.
|- |- LCNXXX.FIL Individual images where L is lander number, C is camera number, N is a letter (a through j), XXX is a number between 0 and 255, and FIL is filter for each image.

6. Image Browser

The image browser contained on this volume is a hypertext based system that provides a simple quick-look capability. The system consists of an HTML page for each image that displays a GIF version of the image and its respective label data.

The starting pointing for the image browser is the INDEX.HTM file in the BROWSE directory.

7. Whom to Contact for Information

For questions concerning this volume set:

PDS - Geosciences Node
Washington University
Dept. of Earth and Planetary Sciences
1 Brookings Drive
St. Louis, MO 63130

WWW Site:
Electronic mail address:

8. Cognizant Persons

This volume set was designed and produced by Edward A. Guinness, Thomas C. Stein, and Jennifer Herron at Washington University.