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Hi Robert,

Here is the information and comments I got back from Russ Dengel last
night regarding use of the LEO command:

> Yes, LEO requires the name(s) of the ADDE navigation datasets in
> order to determine when/if a Satellite will be able to view the
> specified portion of the Earth. This is the initial test performed by
> LEO and it uses the results to generate an ordered list of how the
> datasets are scanned searching for the "best" and most recent view of
> that region. The datasets names are passed to an internally executed
> (mcskeyin) of the NAVCALC command. The results of the NAVCALC command
> are trapped as ASCII text files and then examined to decide coverage
> and view angle to the target.
> Of coarse, you should create a LEODATA.USER or LEODATA.SITE file
> instead of modifying the .CORE file.
> The big question is ... Do they have ADDE navigation datasets?


> RE: Scan for PLR navigation ... Is PLR a Satellite? or is it a
> Instrument?  In either case, the group name for the navigation
> dataset may not be PLR. If they do not have NAV datasets then you are
> probably right about LEO.
> However.....
> Is PLR the only type of data that you are trying to
> display? LEO is designed to find the best/most recent view of a
> target for a collection of sources. If you are only considering 1
> source, then it may be possible to skip the initial NAVCALC step.
> NAVCALC is only used to determine the order of the dataset search. If
> there is only 1, then you already have the answer to the first question.

So, a fundamental/key part in being able to use LEO is access to
NAV servers for the polar orbiters you want to use.  I did not
see NAV service on the SATEPS machine, but that may not mean that
you are dead in the water.  I seem to recall that the navigation
blocks served by the NAV servers are more-or-less the navigation blocks
that are contained in an AREA file created from the image server
using IMGCOPY.  If my memory is correct, it may be possible to collect
NAV blocks from the polar orbiting images in the PLR dataset and create
a holding that could be served by a local NAV server.  This would, of
course, increase the complexity of the processing, but it would be a
way that you could take advantage of LEO.

Is this interesting enough to pursue?


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Ticket Details
Ticket ID: QRJ-934735
Department: Support McIDAS
Priority: Normal
Status: Closed

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