| Accuracy for positions required? [message #213] |
Wed, 19 November 2008 18:28 |
Dr. Volker Knollmann
Messages: 17
Registered: September 2008
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Junior Member |
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Dear all,
I received a question from a (future?) RailML user. He asked to add
accuracy information to Balise locations. In this special case it is
needed to derive the train location uncertainty from the stored balise
position.
I suggest to see this in a wider context. What if we offer the
possibility to store accuracy information for ALL positions?
We could introduce an accuracy-attribute in the attribute groups
"aRelPosition" and "aAbsPosition". Via "tPlacedElement" this would be
inherited to all elements that need positioning. This would be a general
solution.
The attribute could be called something like "posAccuracy" and would
contain the width of the uncertainty interval for the position value. A
posAccuracy of 1 m for example would mean "+/- 0.5 m". Implicitly, we
should assume that the "pos" value is always located in the middle of
the "posAccuracy" range. Additionally we could implicitly assume that
the posAccuracy refers e. g. to the 90%-limits of a gaussian normal
distribution.
In other words: multiple measurements of the position would end up in
90% of all measured values within a range of "pos" +/- "posAccuracy"/2.
What do you think?
Best regards,
Volker Knollmann
--
Dr. Volker Knollmann
RailML Infrastructure Coordinator
EMail: coord(at)infrastructurerailmlorg
Business contact:
Siemens AG
Industry Sector
I MO RA SPP SM21
Ackerstr. 22
38126 Braunschweig
Tel.: +49 (531) 226-2592
mailto:volkerknollmann(at)siemenscom
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