Andrea & all-
in an attempt to address currently open items let me come back to the
issue raised by Andrea Aime / Steven Keens:
Q: should we allow, in WCS 1.2, that null values are identified not only
by a value or a list of values, but additionally by intervals?
Examples:
myIntNullValues = { -65534, [-1 ... +1] }
myFloatNullValues = { 0, [2.71 ... 3.14], [0.999 ... 1.001] }
Background:
- Currently (WCS 1.1.2) allows zero or more null values in
wcsDescribeCoverage.xsd:
0..* ows:CodeType
- in WCS 1.0.0 null values were described by (values.xsd):
0|1 valueEnumType ("Enumeration of TBD values which consists of a
sequence of intervals and/or single values.")
I think I remember we gave up at some time when there was no light at
the end of the complexity tunnel, such as in dealing with open/closed
boundaries (which are present, but not defined 1.0.0).
Arguments:
pro: was possible in WCS 1.0.0, we shouldn' reduce functionality nor
backwards compatbility (and 1.0.0 is important for a significant user group)
pro: especially when dealing with floating point numbers it is unstable
to use specific values and use "==". Intervals allow for a numerically
appropriate handling.
con: adds complexity to a server implementation, and potentially to a
client which attempts to seriously deal with null values. (Of course it
is up to a service to make use of null intervals.)
con: some semantic details seemingly waiting for clarification.
Q to WCS implementors (in particular: GALEON):
1) do you see a need for intervals in your community?
2) would you see null intervals as a severe implementation burden?
thanks,
Peter
--
Dr. Peter Baumann
- Professor of Computer Science, Jacobs University Bremen
www.faculty.iu-bremen.de/pbaumann, mail: p.baumann@xxxxxxxxxxxxxxxxxxxx
tel: +49-421-200-3178, fax: +49-421-200-493178
- Executive Director, rasdaman GmbH Bremen (HRB 147737)
www.rasdaman.com, mail: baumann@xxxxxxxxxxxx
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"A brilliant idea is a job halfdone."
