Dear Gerald,
Yes, this should be subclass of O21 Measurement. We need further
elaboration about how measurements relate to the approximation of things
of interest. I found this to be quite diverse, and adding to this class
a repetition of all topological relations confusing. E18 still has a
Presence directly related.
Best,
Martin
On 3/8/2021 10:07 AM, Hiebel, Gerald wrote:
Dear Martin and all,
thanks for taking this forward and the suggested proposition, which
defines the process very well.
One question I have is how to relate the Position Measurement to the
measured object (E18 or S10).
I believe the E93 Presence is the correct way for it, but we may run
into a problem, as E18 is no longer a subclass of E92 and therefore
not of E93.
For implementation simplicity a shortcut to a measured object in the
form of a specific property would be nice, or could we use O24 measured ?
If so, should we make Position Measurement a subclass of O21
Measurement and maybe include an example that shows the modelling.
But maybe I did not see an obvious solution.
Best,
Gerald
*From: *Crm-sig <[email protected]> on behalf of Martin
Doerr <[email protected]>
*Date: *Monday, 1. March 2021 at 21:31
*To: *crm-sig <[email protected]>
*Subject: *[Crm-sig] Issue 388 measuring position
Dear All,
I revise my previous proposal for measuring positions:
Any position measurement is based
on triangulation with multiples distances to reference points and
angle measurements. GPS measures distances to satellites. Distances
are Dimensions. If directed distances use georeferenced directions,
i.e. angle to the rotation axis of earth, etc. angles
are again dimensions. Hence, a position measurement is an evaluation
of a combination of multiple associated distance and angle
measurements from a particular spot to certain reference points of
known position in the same reference space. If stars are used,
they constitute (extremely) distant reference points. Gravity and
Earth Magnetic Field also provide reference directions for angle
measurements that do not need a second reference point. Classical
longitude measurements use temporal simultaneity of a common
event with a reference location, which evaluates to an angle. All
methods are fairly complex, but the details are a standard routine or
even hidden in a modern GPS module.
Therefore
we argue that position measurement is a specific (composite)
observation which results in a position expression, but the
constituent dimensions may or may not be documented.
Hence,
P40 observed dimension (was observed in): E54 Dimension may not be
instantiated.
All
position measurements are approximations of other places. Therefore,
they result in a declarative place defined by an E94 Space Primitive.
Since in general we talk about moving reference spaces, moving things
and evolving processes, the time of measurement
is essential. We take it either to be the time-span of the
measurement, or a narrower time-span which covers the contributing
time-critical observations. In essence, this defines a declarative
spacetime box (volume), which again is an approximation. It appears
to me that such an approximation would normally be used to determine
parts of the extent of some instance of Presence by overlap, coverage
or containment.
Sxxx
Position Measurement
Subclass
of: E16 Attribute Assignment
Scope
note: This class comprises activities of measuring positions in
space and time. The measured position is intended to approximate a
part or all of the extent of the presence (instance of E93 Presence)
of an instance of E18 Physical Thing or E4 Period of
interest, such as the outer walls of an excavated settlement, the
position of a ship sailing or the start and end of athlete’s run in a
competition. Characteristically, a theodolite or GPS device may be
positioned on some persistent feature. Measuring the
position of the device will yield an approximation of the position of
the feature of interest. Alternatively, some material item may be
observed moving through a measured position at a given time.
A
position measurement is an evaluation of a combination of measurement
of multiple associated distances and/or angles (instances of E54
Dimension) from a particular spot to certain reference points of
previously known position in the same reference space.
Often, the observed constituting dimensions are not documented, or
hidden in an electronic device software.The measured position is given
as an E94 Space Primitive corresponding to a declarative place.
Together with the measured time-span covering the time-critical
observations it forms a spacetime volume, which should normally
overlap with the spatiotemporal extent of the thing or phenomenon of
interest.
Properties:
Oxx1
determined position (was determined by): E94 Space Primitive
Oxx2
has validity time-span (is position validity for): E52 Time-Span
We
may now formulate the approximation to the things of interest, e.g.
Oxx3
overlaps with presence: E93 Presence.
But
the time=span of this presence is already implicit in the time-span of
validity.
If
we use:
Oxx3
overlaps with presence of: XXXX, we need a property for E18 and
another for E4…
Another
use case is when someone wants to determine if she is at a particular
declarative place: Fisherman now mark positions in the sea with GPS,
in order to return to the same spot...
--------------------------------------------
Opinions?
To be discussed!
Martin
--
------------------------------------
Dr. Martin Doerr
Honorary Head of the
Center for Cultural Informatics
Information Systems Laboratory
Institute of Computer Science
Foundation for Research and Technology - Hellas (FORTH)
N.Plastira 100, Vassilika Vouton,
GR70013 Heraklion,Crete,Greece
Vox:+30(2810)391625
Email:[email protected] <mailto:[email protected]>
Web-site:http://www.ics.forth.gr/isl <http://www.ics.forth.gr/isl>
--
------------------------------------
Dr. Martin Doerr
Honorary Head of the
Center for Cultural Informatics
Information Systems Laboratory
Institute of Computer Science
Foundation for Research and Technology - Hellas (FORTH)
N.Plastira 100, Vassilika Vouton,
GR70013 Heraklion,Crete,Greece
Vox:+30(2810)391625
Email: [email protected]
Web-site: http://www.ics.forth.gr/isl
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