Dear Martin, it makes sense to me. I will try to formulate something and thus find out if I actually think something is missing.
Regards, Øyvind > Am 05.03.2021 um 17:47 schrieb Martin Doerr <mar...@ics.forth.gr>: > > Dear Øyvind, > > Indeed I'd call this still a form of triangulation. If you determine the > relative position by (Dx,Dy), you create a rectangular triangle, with your > distance walked being the hypotenuse. > > If you have a nice proposal text to add, welcome! So far, I think I have > covered analogue practices. > > All the best, > > Martin > > On 3/5/2021 5:11 PM, Øyvind Eide wrote: >> Dear Martin, >> >> I am considering a possible practical counter-example from my own manual >> measurement experience. I am not sure if it is relevant but maybe the first >> sentence (”Any position measurement is based on triangulation with multiples >> distances to reference points and angle measurements”) should be modified. >> >> I am mapping the location of a boulder. Using a compass and my steps, fairly >> well calibrated to one meter, I measure the distance and direction from my >> fix point, in this case the spot where a creek is crossing a path. >> >> The fix point itself is established through stereo aerial photography and >> thus, based on a sort of triangulation. But my measurement from the fix >> point and the boulder is based on the distance and direction from the single >> fix point. >> >> Maybe it makes sense to still call this a triangulation as the compass shows >> the direction to the magnetic north. >> >> Whatever can be argued about this, maybe it makes sense to add to the GPS >> descriptions a bit more on analogue measurement practices? They were the >> basis for a massive amount of museum and cultural heritage documentation. >> >> All the best, >> >> Øyvind >> >>> Am 01.03.2021 um 21:19 schrieb Martin Doerr <mar...@ics.forth.gr >>> <mailto:mar...@ics.forth.gr>>: >>> >>> 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: mar...@ics.forth.gr <mailto:mar...@ics.forth.gr> >>> Web-site: http://www.ics.forth.gr/isl >>> <http://www.ics.forth.gr/isl>_______________________________________________ >>> Crm-sig mailing list >>> Crm-sig@ics.forth.gr <mailto:Crm-sig@ics.forth.gr> >>> http://lists.ics.forth.gr/mailman/listinfo/crm-sig >>> <http://lists.ics.forth.gr/mailman/listinfo/crm-sig> >> >> >> >> _______________________________________________ >> Crm-sig mailing list >> Crm-sig@ics.forth.gr <mailto:Crm-sig@ics.forth.gr> >> http://lists.ics.forth.gr/mailman/listinfo/crm-sig >> <http://lists.ics.forth.gr/mailman/listinfo/crm-sig> > > > -- > ------------------------------------ > 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: mar...@ics.forth.gr <mailto:mar...@ics.forth.gr> > Web-site: http://www.ics.forth.gr/isl > <http://www.ics.forth.gr/isl>_______________________________________________ > Crm-sig mailing list > Crm-sig@ics.forth.gr > http://lists.ics.forth.gr/mailman/listinfo/crm-sig
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