3 Overview of VICAR

3.1   Background
    3.1.1   VICAR Changes Under UNIX
3.2   Applications of VICAR
3.3   System Acquisition

3.1 Background

VICAR is a set of computer programs and procedures designed to facilitate the acquisition, processing and handling of digital image data. The VICAR image processing language was defined by JPL employees Stan Bressler, Howard Frieden and Fred Billingsley, and implemented in 1966 at the Jet Propulsion Laboratory to process image data produced by the planetary exploration program. The software package was originally designed for operation with the IBM 360/44 Programming System (44PS) and was later modified to run with the IBM OS/360 operating system. In the early 1980's VICAR underwent a major revision to run under the VMS operating system on the VAX series of Digital Equipment Corporation computers. Now, in the early 1990's, VICAR is once again undergoing a major revision and will soon be fully operational under both the SunOS and Solaris UNIX operating systems.

For its command-line interface, VICAR makes use of the Transportable Applications Executive (TAE) that was developed by the NASA Goddard Space Flight Center. This version of VICAR makes use of several enhancements to TAE, which should be included with your version of VICAR. Several VICAR programs may not run without these enhancements.

The VICAR executive is a body of software that forms the interface between the user, the library of application programs and procedures, and the computer's operating system. The VICAR executive does not replace the host computer's operating system; instead, it overlays the host resources. The objectives of the VICAR executive are to:

VICAR's application library contains an extensive assortment of programs and procedures to perform a wide variety of functions (Appendices 10.1, 10.2 and 10.3). These programs are written in standard programming languages, FORTRAN, C and C++, with small segments in VAX assembler and array processor code (not portable code).

The user interfaces with the VICAR executive via a series of TAE Command Language (TCL) statements (Section 7.1). Through TCL, the user directs VICAR to invoke the programs, procedures and commands to perform the analytical and housekeeping activities necessary to complete a required task.

Programs interface with the VICAR executive via a standard set of subroutines that perform image, label and parameter processing plus control several external devices such as display devices and printers (Figure 3.1). The interface is known as the VICAR Run-time Library (see the VICAR Run-time Library Reference Manual). Other libraries exist that provide access to databases, external devices such as display devices and printers, etc. The subroutines are designed to reduce some of the routine labor involved in writing an application program.

Because of its modular architecture and portability, the VICAR system will continue to grow. New capabilities are being added to take advantage of new technology, to meet the demands of the user, and to provide support for new application areas.


	     Figure 3.1  VICAR Program Interface

3.1.1 VICAR Changes Under UNIX

For the most part, the changes to VICAR that enable it to run on the UNIX operating system should be transparent to the user. However, there are a few things that have changed that the user should be aware of. These differences between the VAX/VMS and UNIX VICAR systems are covered in the following subsections:

There is also an NCSA Mosaic page, Using VICAR under UNIX, detailing the differences between VAX/VMS and UNIX VICAR.

3.2 Applications of VICAR

VICAR's application has expanded over time and now supports image processing for many disciplines: planetary imaging, astronomy, earth resources, land use, biomedicine and forensics. Facilities using VICAR are world-wide and include: universities, the military, research institutions, aerospace corporations, commercial/industrial companies and the Galileo HIIPS (Home Institution Image Processing Subsystem) sites.

3.3 System Acquisition

VICAR is available to organizations through the Computer Software Management and Information Center (COSMIC):

		Software Information Services
		Computer Services Annex
		The University of Georgia
		Athens, Georgia 30602


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