-01570.-
he most promising satellite MSS data for multitemporal studies of
earth resources can only be obtained if careful consideration is given to the followin
factors (Figure 2): cloud cover, image quality, snow cover, bio-climate
(soil moisture), vegetation/crops and sidelap. The above factors are
important for both visual interpretation as well as digital analysis of
Landsat MSS data.
The selection and ordering of Satellite MSS data for earth resources
surveys is a time consuming process, taking six to eight weeks (depending
on postal services and customs clearance) for a non-US resident even
when the order is placed at the most efficient of all distribution centres
EDC, USA. In Europe, airmail parcels valued at less than $ 100
generally meet with no delay during delivery.
Landsat reference systems, maps, catalogues and micro fiches
The US Geological Survey has published in 1975 a series of 1:9 million
and 1:18 million Landsat maps covering the whole world with five cloud
cover classes. The World Bank issued a Landsat Atlas (1976) of the
Developing Countries of the World, in which Cuba and China have been
omitted together with Western Europe and the USSR, but countries like
Ireland, Spain, Israel and Iran, to mention just a few, have been included.
Telespazio, Italy,and the Instituto de Pesquisas Especiais (ENPE), Brasil
have issued maps with path and row number of the area over which they
can receive Landsat MSS data in real time. One may conclude that existing
maps and catalogues provide partial and out-of-date information on
available imagery.
Two new reference systems that will provide users with quick and inexpensive
access to Landsat data have been developed by the EROS Data Center with
support from the National Cartographic Information Center.
Called the Landsat micro-catalog and Landsat micro-image systems, these
products use standard microfiche records to replace the paper catalogues
and roll microfilm of 'browse' images that were previously the basic tools
tools for Landsat information (Landsat Users Note, No. 2, May 1918).
A subscription to one of the above reference systems is of great use to
major customers requiring areas which are not covered by Telespazio &
INPE.
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