Remote Sensing Resources at the British Library

Remote sensing has rapidly become an important interdisciplinary research tool used in such fields as geology, agriculture, forestry, land use, oceanography and cartography. One of the first hurdles to confront a user is the vast amount and diversity of imagery available. To help such users, the British Library, since 1972, has offered search and browse facilities for Landsat and other imagery. Originally located at the B.L. Science Reference Library, the service has now been transferred to the B.L. Map Library where it has been updated and expanded following the recommendation made by the House of Lords Select Committee on Science and Technology (Sub-ComIl)ittee I, Remote Sensing and Digital Mapping) that the British Library should become the retrospective archive for remote sensing imagery of the Uoited Kingdom. The archive consists of colour composite Landsat imagery of those scenes that cover the British Isles from the initiation of the Landsat programme in 1972 to the present. Only those images of good quality and in particular, low cloud cover have been chosen. Each image is a nominal 240mm x 240mm. , at a scale of 1:1,000,000 and represents a scene area of 185 x 185km. Some Thematic Mapper (TM) quarter images at a scale of 1:500,000 are also available. The archive is divided into three sections, Landsats 1-3 and 4-5 Multispectral Scanner (MSS) imagery, and Landsat 4-5 TM imagery. Each section is arranged by the path and row of the Worldwide Referencing System (the Landsat geographic location index) and then by accession number. For each scene, denoted by a particular path/row, several images taken at different times may be available so enabling comparisons to be made between years and between different times of the year. There are 300 images in the archive, increasing by 25 per month to 600 while current images are received. Perhaps the most useful, and certainly the most popular remote sensing resource at the B.L. Map Library is the Eros Data Center's "Microcatalog". This is a comprehensive microfiche catalogue which shows the availability and characteristics of Landsat data worldwide. In conjunction with the browse fues of imagery, it enables the enquirer to select imagery he or she requires and to actually see the image in the browse files. The coverage, cloud cover and quality can be seen before purchase; the enquirer does not have to rely solely on computer print-out the normal method of imagery selection. The Microcatalog which is updated regularly is arranged by path and row of the Worldwide Referencing System and then subdivided chronologically. Information given for each image includes date, which satellite e.g. Landsat 1, 2 etc., image quality of the bands, percentage cloud cover, centre coordinates and scene ID (the number to quote when ordering imagery). Also included is the microform number which refers to the browse fues of imagery. Most images are held in 16min fum format but from 1985 they are available on microfiche, a definite improvement in both quality and handling. Again the browse ftles are regularly updated. The remote sensing information point in the BL Map Library. A frame of the Landsat Microcatalog is mounted on the fiche reader while to the left an image from the 16mm browse fIles is shown. In the foreground a user consults some imagery from the archive of U.K. imagery.