Content
Updating
How can I access it ?
The Dali catalogue, located on Spot Image premises in Toulouse,
contains "metadata" describing all scenes acquired by the Spot
system since the launching of SPOT 1 in February 1986. A scene's "metadata"
are a set of alphanumeric items describing its main technical characteristics
(acquisition date, spectral mode, viewing angle, latitude & longitude, etc.).
The catalogue also includes a "quick-look", a subsampled
representation of each SPOT scene. On average, a quick-look contains one pixel
for every 36 in the full scene. This relatively small volume of image data gives an
overview of the full scene and can be transmitted quickly while remaining perfectly
usable. Quick-looks are available for all SPOT scenes received by the Toulouse and Kiruna
stations since 1991 as well as for scenes received by certain other direct receiving stations since
1995.
As of late 1997, the DALI catalogue held :
- Metadata for over 5.4 million SPOT scenes, 56% received by the Toulouse
and Kiruna stations, the remainder by direct receiving stations.
- Over 2.2 million quick-looks.
Virtually every square metre of exposed land is represented.
top of page, article, section
The Dali catalogue is updated :
- every day, via 64-kbit/s dedicated computer links, and within a few hours of data
acquisition, for imagery received by the Toulouse and Kiruna stations;
- every day or week, via X.25, ISDN or Internet connections, for imagery received by
certain direct receiving stations;
- every week or month, through the physical delivery of CCTs, CD-Roms or Exabyte
cartridges, for imagery received by other direct receiving stations.
top of page, article, section
You can access the Dali catalogue in four ways :
- Using the navigation function of the Dali Type 1 software package
available from Spot Image for use with Macintosh computers (PowerPC processor
recommended). This package helps the user to query the catalogue, manages the
communications link, and downloads and displays metadata and quick-looks. The link with
Spot Image, Toulouse, is established via an ISDN, X.25 or Internet connection.
- Via the World Wide Web using a browser such as Netscape Navigator or
Microsoft Internet Explorer. This method offers virtually the same capabilities as access
using the Dali Type 1 package. Direct link to the Dali
catalogue.
- Using the Dali Type 3 metadata search function. This pure-alphanumeric
mode (emulation of a VT 100 console) uses a dedicated search language known as LAS to
launch searches by scene location. Search results can be downloaded using the SCIE
(Standard Catalogue Information Exchange Format) format. This allows users to transfer
search results to their own computer, then set up and manage a local database, and so
forth. The link with Spot Image,
Toulouse, is established via a standard telephone connection, using a modem, or via an
X.25 network. Some 160 subscribers worldwide currently use this mode of access.
- Using the Diva metadata management tool. This consists of a software package based on
the MapInfo® geographic information system running on a PC. Diva emulates the LAS query
language.
By sorting metadata and display scene outlines on an underlying map (e.g. DCW),
subscribers can obtain answers to such questions as "how can I obtain optimal
coverage of my region of interest?"
This package also allows the user to access the Dali catalogue, to formulate queries using
graphic tools and maps and to download the results.
The link is established via a standard telephone connection, using a modem, or via an X.25
network.
MapInfo is a registered trademark of MapInfo Corp.
top of page, article, section
page updated on the 04-09-29