Stas and All, Would the coordinate precision in Wikidata and Query Service allow us now to move to the cellular and even the atomic and subatomic levels, say, for example, when querying for differences between microscopic species in a piece of earth in a municipality that might be rich in smallest life forms - say differences between nanobes https://en.wikipedia.org/wiki/Nanobe ? And would Wikidata want even further precision for knowledge generation based on what we might learn from expansion microcopy e.g. Ed Boyden's work at MIT - say in brain science - https://www.youtube.com/watch?v=bPlr31LrT0g ?
Scott On Tue, Aug 29, 2017 at 2:13 PM, Stas Malyshev <smalys...@wikimedia.org> wrote: > Hi! > > I would like to initiate a discussion about coordinate precision in > Wikidata and Query Service. The reason is that right now we do not have > any limit to precision, coordinates are basically doubles, and that > allows to specify over-precise coordinates and makes it harder to > compare them - both between themselves within Wikidata and with outside > services. > > From the precision description in [1], we would rarely need beyond third > or fourth digit after the decimal point. However, we have in the > database coordinates like: Point(13.366666666 41.766666666) which > pretends to specify it with sub-millimeter accuracy - for an entity that > describes a municipality[2]! > > We do have precision on values - e.g. the above has specified precision > of "arcseconds" - so it may be just a formatting issue, but even > arcsecond looks somewhat over-precise for a city. And it may be a bit > challenging to convert DMS precision DD precision. > > But the bigger question is whether we should store over-precise > coordinates in the database at all, or we should round them up on export > or inside the data. The formulae that are used to calculate distances > have, by obvious reasons, limited precision, and direct comparisons > can't take precision into account, which may lead to such coordinates > very hard to work with. Should we maybe just put a limit on how precise > we put coordinates into RDF and in query service? Would four decimals > after the dot be enough? According to [4] this is what commercial GPS > device can provide. If not, why and which accuracy would be appropriate? > > We do export precision of the coordinate as wikibase:geoPrecision[3] - > and we currently have 258060 distinct values for it. This is very weird. > I am not sure precision is useful in this form. Can anybody tell me any > use case for this number now? If not, maybe we should change how we > represent it. I'm also not sure where these come from as we only have > 13 options in the UI. Bots? > > [1] https://en.wikipedia.org/wiki/Decimal_degrees > [2] https://www.wikidata.org/wiki/Q116746 > [3] > https://www.mediawiki.org/wiki/Wikibase/Indexing/RDF_ > Dump_Format#Globe_coordinate > [4] > https://gis.stackexchange.com/questions/8650/measuring- > accuracy-of-latitude-and-longitude > > -- > Stas Malyshev > smalys...@wikimedia.org > > _______________________________________________ > Wikidata mailing list > Wikidata@lists.wikimedia.org > https://lists.wikimedia.org/mailman/listinfo/wikidata > -- -- - Scott MacLeod - Founder & President - World University and School - http://worlduniversityandschool.org - 415 480 4577 - http://scottmacleod.com - CC World University and School - like CC Wikipedia with best STEM-centric CC OpenCourseWare - incorporated as a nonprofit university and school in California, and is a U.S. 501 (c) (3) tax-exempt educational organization. IMPORTANT NOTICE: This transmission and any attachments are intended only for the use of the individual or entity to which they are addressed and may contain information that is privileged, confidential, or exempt from disclosure under applicable federal or state laws. If the reader of this transmission is not the intended recipient, you are hereby notified that any use, dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this transmission in error, please notify me immediately by email or telephone. World University and School is sending you this because of your interest in free, online, higher education. If you don't want to receive these, please reply with 'unsubscribe' in the body of the email, leaving the subject line intact. Thank you.
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