The strategy of the project in relation to the loading of metadata has been to use existing metadata to the maximum degree possible. In particular, metadata generated by outside agencies has been loaded into the Alexandria Catalog and considerable maintenance (or quality control) has been performed on this metadata (see below for details.) The Alexandria Metadata Schema is used for creating and loading metadata for aerial photographs and satellite images. For hardcopy maps and for CD-ROMs, we have obtained metadata records from OCLC (a library utility for cataloging and interlibrary loan), and are moving these into the Davidson Library's online catalog, PEGASUS.
Quality Control of Metadata
To avoid the ingest of incorrect metadata into the catalog component, we have several points for quality control. In particular, quality checks are performed during the key-entry of metadata records, with SQL statements, and upon entry into the full database. During the past year we examined metadata records in order to monitor them for mistakes and inconsistencies. One method involved entering the database and selecting all the unique values for a given field. Several fields have restricted domain values, so the values of the result set and domain were compared. On this basis, improper entries were corrected. It is possible for errors to escape the earlier quality control checks, particularly for fields having many possible values. As a result of these edits on the database, Alexandria's catalog is closer to 100% consistency. With approximately 500,000 records to check, however, the process is a time-consuming and never-ending task.
Loading of Metadatasets: SNEP, EDAC, Coproj, Mojave
The activity of loading new datasets into the Alexandria catalog is on-going and a variety of new datasets were loaded over the previous year, particularly in cooperation with several of our partners. We used a forms-based cataloging aid to help such partners to load the metadata. In particular, we used Microsoft Access software to build a forms interface on top of the Alexandria catalog schema. The resulting forms are easy to use and partners, such as the Earth Data Analysis Center in New Mexico, were able to enter new catalog information directly into Alexandria's schema.
Prior to a dataset being loaded into the Alexandria catalog, we crosswalked the metadata fields from the dataset into Alexandria fields. This iterative process required that we worked closely with the participating partner to fully understand the nature of each field before assigning its value to an appropriate field in Alexandria. We ingested directly into ADL the metadata of partners with digital metadata in cataloged form, without having to re-key the values. The crosswalking activity is an important aspect of efficiency and accuracy in the loading of metadata.
Earth Data Analysis Center
The Earth Data Analysis Center (EDAC) at the University of New Mexico, partnered with Alexandria to load over 50 records of satellite images and aerial photographs. Alexandria and EDAC at first shared their respective data models to find the common ground. It was determined that EDAC's existing database contained the necessary fields to crosswalk into Alexandria, except for the omission of a field for coordinates. Alexandria provided two procedures for extracting coordinates, which EDAC implemented.
The metadata fields supplied to Alexandria from EDAC were entered into a customized Access form. This form went through several revisions before the final version. As much as possible, the form was built to limit the amount of data-entry time and to assist in consistency. The records were then entered into the ADL catalog and made available via ADL's Web interface. This small sample was intended to provide access to persons seeking spatial data for New Mexico who do not reside near EDAC's offices. Alexandria will continue to support the existing records.
National Park Service
Alexandria has shared information and data with the National Park Service (NPS), which has an interest in our forms-based interface based on Microsoft Access. On the basis of our interface, the NPS produced their own in-house Access Form to be used by field agents. The NPS provided Alexandria with several small databases of Park information including naming conventions, park boundaries, workbooks, as well as several CD-ROMs of scanned maps.
Alexandria plans to incorporate these NPS databases into the Alexandria catalog and gazetteer. The scanned images of maps received by Alexandria will be loaded into the catalog, with references made to the NPS's home page as another source of NPS data. An additional set of Digital Orthophoto Quads of the Virgin Islands will also be loaded. Alexandria and the NPS will continue to cooperate in the area of metadata.
Sierra Nevada Ecosystem Project
The Sierra Nevada Ecosystem Project (SNEP) is a congressionally mandated 3 year study of the entire Sierra Nevada range. The Project produced a full report of their study as well as the more than 300 GIS coverages. SNEP worked closely with Project Alexandria to catalog their collection items and to have these items and the full datasets made accessible through Alexandria. In particular, Alexandria worked with SNEP to catalog their datasets in a way comforming to ADL's standards and to ingest their metadata from their schema into the Alexandria schema. We constructed a forms-based interface in Microsoft Access which SNEP used to enter their records which were then mapped to the Alexandria schema. In addition to the metadata and actual data, SNEP provided browse graphic images associated with each coverage. These are graphical representations of datasets which users may view during an ADL search process. The SNEP report is available from Alexandria's web page and contains detailed information on the project and its findings.
Approximately 1,100 spatial data records have been loaded into the Davidson Library's online catalog, PEGASUS, so that when PEGASUS is upgraded, these records may be ingested into Alexandria. The Alexandria MS Access interface is currently being used to transfer hardcopy metadata for air photo flights into the the Alexandria Catalog.
Metadata Manuals
We have written customized manuals to assist these various partners in entering their metadata. The manuals consist of introductory materials, mathematical conversions, field formats, and help tailored to specific fields. These documents serve as a reference guide for each group.
Metadata web page on ADL
In addition to making this manual available from our web site, we have authored and made accessible useful metadata resources, including papers, the Alexandria ingest procedures, the history of the Alexandria metadata schema, tools for creating metadata, standards used for metadata, and details of crosswalks of the ADL schema to other schemas such as USMARC and FGDC. The Alexandria Metadata Manual is currently limited to instructions for creating metadata for aerial photography and for scans of aerial photography.
Core set of metadata to FGDC for inclusion in a CD-ROM
During the past year Alexandria participated in the production of a CD-ROM of FGDC-compliant metadata, in cooperation with the USGS. Several contributing participants provided metadata with pointers to actual digital data available online. Since the Alexandria schema goes well beyond the FGDC standard, we submitted a subset of our entire schema to the CD-ROM project.
Issues Concerning Coordinates
The determination of geospatial coordinates is an important but difficult aspect of creating metadata in ADL. While this process is simple in the case of digital datasets which already have this information available, there many items that we must load, such as air photos, for which it is time-consuming to extract and record geospatial coordinates. In the case of air photos, we use a digitizing tablet and GIS or image-processing software to retrieve corner points for each image. We are refining this process and investigating other methods for extracting geospatial coordinates.