The system design and system operating plans provide for the creation
of special photographic products, using processing algorithms different
than those used for standard products. By retrospective order to GSFC
we can also acquire and process, on behalf of a user, data that have
not been resampled, data that have been resampled by the "nearest
neighbor" algorithm, and data that have been fit to a Universal Transverse
Mercator or Polar Steorographic projection.
Implementation of the new system will have little visible impact on the
traditional user of EDC image products, except to provide images of
improved density and resolution. The geometric properties of the images
will improve continuously over the next several years as the library of
ground control points is expanded and referenced for computing the
geometric corrections. Initially images will be processed against
"image control points" whose geodetic accuracy is undetermined. This
will allow repetitive images to be registered one to another but will
not necessarily improve image-to-map registration. As geodetically
accurate control points are identified and used, the cartographic
accuracy of the products will improve.
Implementation of the new system will have a dramatic effect on the
users of computer compatible tapes (CCT's) -- all for the good. We
will no longer need to order the master tape (for standard products)
retrospectively from Goddard. This action historically has added from
30 to 180 days to the delivery time. Because the master tape is stored
at EDC, CCT's of data resampled by cubic convolution to the HOM
projection can be produced a few days after receipt of an order. A
further benefit to the CCT user is the fact that CCT users will have a
choice of pixel sequencing on the tapes. The data will be available in
"band sequential" or "band-interleaved-by-line" data sequences, with
packing densities of 800 or 1600 bits-per-inch.
Both elements of the data processing system are currently producing test
products; routine data production will begin in the early fall of this
year.
Another significant improvement in the delivery of Landsat products in
the U.S. will be affected with the installation of communication
satellite transmission capabilities at the three receiving stations,
transmit-receive capability at GSFC, and reception capability at EDC.
The data now have to be physically transported from the receiving
stations to GSFC and from GSFC to EDC. The output products are normally
available to the user in about 45 days after acquisition by the satellite.
This time should be reduced to about 15 days with communication satellite
relay of the data, beginning in late 1978.
International Catalog of Landsat Acquisitions
The number of Landsat receiving stations outside the United States is
continuing to grow. The activities of these ground stations are
coordinated by the Landsat Ground Station Operators Working Group. As
a member of that group, EDC has volunteered to coordinate the compilation
of a unified data base of Landsat acquisitions. At present, users may
have to contact several sources to identify all of the Landsat acquisitions
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