Metadata Converter 1.6 [Extra Quality]

A raw file contains the "raw" data captured by the digital camera sensor before it has been converted to JPEG or TIFF formats. Cameras that create JPEG or TIFF files process (and in the case of JPEG files, compress) the sensor data. When working with raw files, the file is not compressed or processed in the camera. Instead, software gives the user complete control over the conversion settings. For example, white balance is not applied to the raw file but is stored with the file so the software can default to the originally-intended setting. Other information contained in a DNG file includes standard EXIF metadata (just like in JPEG files), date, time, camera used, and camera settings.

Metadata Converter 1.6

Digital Negative (DNG) is an openly published raw file specification that stores the "raw" pixel data captured by the digital camera sensor before it has been converted to JPEG or TIFF formats, along with standard EXIF metadata, date, time, camera used, and camera settings. This format is freely available for other software and hardware vendors to support.

The Digital Negative specification allows for not only all of the pixel information stored in current raw formats, but also for all of the additional, proprietary metadata that many manufacturers include. The Adobe DNG Converter may, in some cases, ignore some of this proprietary metadata, and only include the basic information necessary for creating a high-quality image file. The original raw file, however, can also be embedded in the new DNG format to ensure that proprietary metadata from the manufacturer is not lost.

Alaaeldin M. HafezCenter for Advanced Computer StudiesUniversity of Louisiana LafayetteLafayette, Louisiana ahafez@cacs.usl.edu Abstract The purpose of this article is to raise and address a number of issues related to the conversion of Federal Geographic Data Committee metadata into MARC21 and Dublin Core. We present an analysis of 466 FGDC metadata records housed in the National Biological Information Infrastructure (NBII) node of the FGDC Clearinghouse, with special emphasis on the length of fields and the total length of records in this set. One of our contributions is a 34 element crosswalk, a proposal that takes into consideration the constraints of the MARC21 standard as implemented in OCLC's World Cat and the realities of user behavior.

This paper describes a continuing digital library research project at the Energy and Environmental Information Resources Center to enhance access to Federal Geographic Data Committee (FGDC) data sets.[1] It presents a mapping of selected FGDC metadata elements into Dublin Core (DC) and MARC21 metadata that is based on standard crosswalks [Mangan 1997; LC 1999]. The FGDC elements included in our mapping are referred to as "essential FGDC metadata." They provide the basis for a converter being developed to import FGDC metadata into the Online Computer Library Center's WorldCat, its Cooperative Online Resource Catalog (CORC) project, and into local MARC-based library catalogs. We also analyze a data set of 466 FGDC records: 1) as a criterion for selecting essential FGDC elements, and 2) in terms of FGDC record length, because record and field lengths are a limitation for records in WorldCat and often in local library systems.

We are following two research threads: the first is to create an alternative Clearinghouse model that makes management and maintenance of the metadata easier for the individuals responsible for taking time to create FGDC compatible metadata; the second is to convert existing and future metadata to more widely used metadata standards for inclusion in systems other than the Clearinghouse. Our metadata converter model addresses both concerns. (The permanent URL for our converter project is: .) Before describing our project, however, it may be useful to first offer some important definitions for readers who are not professional librarians.

The Cooperative Online Research Catalog (CORC) is an initiative sponsored by OCLC to develop the creation and sharing by libraries of metadata for Internet resources. Some of the main features of CORC are the integration of Dublin Core and MARC21 metadata into a single system that provides for both shared and local metadata for digital and physical items, editing in DC and MARC21 views, import and export of DC and MARC21 records, RDF/XML import and export, authority control, assisted (DDC) classification and subject heading assignment, automated keyword extraction and data extraction, link maintenance, and Unicode support [CORC 1999].

FGDC metadata is based on the "Content Standard of Digital Geospatial Metadata" [FGDC 1998]. The standard is available in several electronic formats, for example, as hyptertext images [CSDGM Image Map 1998]. FGDC metadata has a hierarchic structure of more than 300 elements, including 199 data entry elements, that are organized into seven information sections and three supporting sections called templates:

Sections and elements are either mandatory, mandatory if applicable, or optional. Templates are not used alone, but are inserted into information sections at appropriate places. Some data elements are repeatable, as are the templates. Only the Identification and Metadata Reference sections (sections 1 and 7) are mandatory in a fully compliant FGDC metadata record.

The model we are approaching to address this reliability problem eliminates the complicated Z39.50 based nodes. Instead, researchers will register the location of their metadata files with a central search engine/converter. During this registration process, a unique persistent identifier will be assigned for each full metadata record. At that point, the content of the file will be ingestedinto this centralized portal which will offer features such as searching, browsing, and conversion to MARC21 or other metadata standards. We will be reporting on a working prototype of this model in the months ahead.

Accordingly, we obtained a data set of 466 metadata records from the National Biological Information Infrastructure (NBII) of the U.S. Geological Survey.[2] The output of the SGML format maps into a flat text file of 444 element cells for each record. A summary of results is presented in Table 1. For those interested in examining the data in more detail, see Appendix A: NBII Data.

It is clear that the FGDC metadata in this set is, essentially, of a different type than the typical catalog record found in WorldCat. The largest record in the set contains 28042 bytes, that is, nearly seven times larger than the WorldCat record length limit. The largest field value is about eight times larger than the WorldCat field limit. In fact, about 74% of this set exceeds the maximum record size, while 51% of the records have at least one field, usually the abstract (element 14 in our output), distributor liability statement (element 376), or the process description (element 135) that exceeds the field length limit in WorldCat.

It is not our intention to map and convert all 300-plus FGDC elements (or 195 data entry elements). Rather, we selected a smaller number of elements that we refer to as "essential FGDC metadata" for a fully compliant FGDC record. Elements were selected for three reasons: 1) they are required (mandatory) for the production of a fully compliant FGDC record; 2) they are search keys such as author, title, subject, and date that are commonly found in online library catalogs; 3) they are fields commonly used by creators of FGDC metadata that may be used as search keys by persons interested in FGDC geospatial data sets. The first two criteria are determined, respectively, from mandatory elements in the "Content Standard for Digital Geospatial Metadata" (CSDGM) and by generally accepted library practice for the selection of access points in online catalogs. The third criterion is based on a frequency analysis of the NBII data set for actual usage of FGDC elements by persons who created the metadata records. The results of this analysis are presented in Table 2.

The following table (Table 3) presents our crosswalk from FGDC to Dublin Core and MARC21. It consists of 34 essential FGDC elements and is based on standard crosswalks [LC 1999; Mangan 1997].[3] It includes mandatory elements from the Identification and Metadata Reference sections, as well as specific elements from the Spatial Reference, Distribution, Citation, Time Period, and Contact sections. Our crosswalk has similarities as well as differences with the "Metadata Entry System" for minimally compliant metadata that has been proposed recently by the Federal Geographic Data Committee [FGDC 1999]. We recommend that the reader compare those guidelines with the elements in our crosswalk. Appendix B contains a detailed discussion of the essential FGDC metadata elements.

The crosswalk and converter represent the current state of an evolving process rather than a final product. The converter software program is written in C by one of us (Alaaeldin Hafez). It has a modular and adaptable design, that is, it is very easy to add, change, or delete particular features within its general design. However, even the best machine conversion may require some human intervention: in other words, librarians may want to do some editing of records produced by the converter in order to adapt them to their local automated library systems. It also includes our reasons why there are temporary blank spaces in the crosswalk in Table 3.

The realities of mapping FGDC to MARC21 and Dublin Core standards are most clearly understood by examining the record and field length limits of the OCLC WorldCat system. It is our supposition that there are others who are interested in putting FGDC records into their local MARC21 library systems to increase the access points and availability of this valuable metadata. The whole notion of cooperative cataloging mandates that we look for least common denominators for our metadata standards. While some library automation systems do not impose the same kind of limits as WorldCat, it would be counterproductive to design individual crosswalks for each library vendor's system. 041b061a72