Wikipedia talk:WikiProject Geographical coordinates

Change to precision tables

I'm mulling the idea of removing the 0° columns from the tables at WP:COORDPREC, but I wanted to seek some comments first. A close look at the tables reveals that this change would affect only one narrow set of cases: DMS format coordinates, object size ~300km-750km, latitude 0°-15°. The table currently suggests d° m' for those cases and that would become d°. So I wonder whether the 0° columns earn their keep. While removing the 0° column from the decimal-format table alone would have no effect at all, I'd prefer to keep the table formats consistent with each other. ―Mandruss ☎ 13:44, 2 October 2017 (UTC)

I have been concerned about the practice of rounding off the location of objects based on the size of the object, instead of the precision with which the data was gathered, or if that is unknown, the precision with which the data was stated in the source. While studying this, I used ARCGIS to make a map of Vermont with town and city boundaries downloaded from the VCGI's Open Geodata Portal. I then added green diamonds that represent the full-precision latitude and longitude of Vermont towns and cities from the US Census Bureau. Finally, I selected some of these towns and rounded the latitude and longitude as directed by the table that Mandruss is asking about in this thread, and plotted the results with orange triangles. Here is the result:

Vermont city and town boundaries for discussion.

I found that the US Census lat and long were not necessarily centered in the boundary. When I rounded, I found the magnitude of the shift was large enough to move the point outside the boundary of the town. However, in the examples I tried, the shift was in a lucky direction and the point didn't move outside the boundary. But I feel safe in saying if this procedure was repeated on a large enough sample, there would be cases where the point ends up outside the boundary. Jc3s5h (talk) 15:42, 2 October 2017 (UTC)

@Jc3s5h: I was afraid this would segue into a discussion of coordinates precision. I don't like to use the word "hijack", but maybe we could keep that separate? ―Mandruss ☎ 15:47, 2 October 2017 (UTC)

Well, since I've demonstrated the rounding is already too loose, any change that promotes rougher rounding would be bad. Jc3s5h (talk) 15:55, 2 October 2017 (UTC)

Have you demonstrated that rounding is too loose for object size ~300km-750km, latitude 0°-15°? Anyway, 1. I don't think anybody would object to using one level more precision than the tables recommend if that's necessary to keep the marker within the boundaries. 2. I don't think any source of coordinates is inherently more authoritative than Google Maps and the human eyeball, for locations that are not disputed, controversial, or ambiguous. If the source's coordinates create a problem, we don't have to use that source. ―Mandruss ☎ 16:02, 2 October 2017 (UTC)

I have not examined the case of object size ~300km-750km, latitude 0°-15°. The table is not restricted to any particular source of coordinates. We can expect that bot authors might use the table to control the rounding behavior of the bots. Bots would typically obtain latitudes and longitudes that make that readily available in text or database form. Such sources may not have a goal of centering the point in the shape. Their goal may be to place the point at the capital of a country, courthouse in the county seat of a county, city hall of a city, etc. And bots certainly don't have eyeballs. And when bots make mistakes, they make a large number of mistakes. Jc3s5h (talk) 16:40, 2≥ October 2017 (UTC)

Overprecision

I think you guys might be being overprecise by several orders of magnitude. I have never needed to go more precise than 0.5" to mark even such objects as statues. I was told at here at WP:Geographical_coordinates many years ago to stick to arcseconds or to dd.dddd° (four digits) for the most precision one would ever need. Abductive (reasoning) 05:29, 3 October 2017 (UTC)

I do more camera locations, and for those I like one more digit especially when using DMS. Of course, it also depends on source. Google Earth aerial photography is usually consistent to a meter or three in the New York metro area but Pittsburgh is often ten times as rough. Historic site databases often add several digits precision when converting to decimal degrees, thus misleading the unwary. So, be wary. Jim.henderson (talk) 17:44, 17 November 2017 (UTC)

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Schools w/ multiple campuses

How do I attach more than one set of coordinates to an article? Several schools for example have multiple campuses and I want to add the data for all campuses.

Thanks WhisperToMe (talk) 01:09, 3 December 2017 (UTC)

You can put coordinates anywhere you want in an article. Just code a {{Coord}} with |display=inline (that's the default, so you can alternatively omit the |display= parameter). Pioneer Library System shows one method using a table. Norman, Oklahoma#Geography includes coordinates within the text. Optionally, you can include a {{GeoGroup}} in "External links" to allow display of all the article's coordinates on one map; see Pioneer Library System#External links. ―Mandruss ☎ 04:24, 3 December 2017 (UTC)

Thank you so much! WhisperToMe (talk) 06:36, 4 December 2017 (UTC)

Proposed merge

There is a proposal to merge Vertical metre into Metres above sea level. Please feel free to join in the discussion at Talk:Metres above sea level#Vertical metre merge. —hike395 (talk) 13:29, 29 December 2017 (UTC)

Template:GeoGroup

I made some changes to the GeoGroup template. See discussion on template talk page - Samuel Wiki (talk) 07:44, 20 January 2018 (UTC)

Whitlingham Geohack link

The Geohack link arrived at by clicking on the coordinates on the Whitlingham article has 'Wikimedia maps' on the RHS rather than 'Great Britain', I have noticed that the region parameter in the panel at the top is missing, it should be 'GB', any ideas ? Thanks GrahamHardy (talk) 09:10, 28 January 2018 (UTC)

@GrahamHardy: I added region and type.[1] Is that better? ―Mandruss ☎ 10:07, 28 January 2018 (UTC)

Brilliant, Thanks GrahamHardy (talk)

Removal of precision tables

Re: [2]

@Abductive: As stated below the tables, the target resolution is one-tenth of the object size. Let's look at the case you cited, object size 1 m at 45°, dms format. The table should recommend the precision that yields a resolution closest to one-tenth of 1 m, or 10 cm. The precisions to be compared are:

d° m' s.ss" = 22 cm resolution per WP:OPCOORD; 10 - 22 = -12, absolute value 12
d° m' s.sss" = 2.2 cm resolution; 10 - 2.2 = 7.8
d° m' s.ssss" = 0.22 cm resolution; 10 - 0.22 = 9.78

The lowest bolded value of the three is 7.8, so d° m' s.sss" is the best dms precision for that case, and that is the precision shown in the table.
I know you have voiced opposition to the tables before, but it was for reasons other than inaccuracy. Feel free to start a discussion about that, but please don't remove the tables without a substantial consensus to do so, and certainly not with the false rationale that "This usage table is profoundly wrong." The tables have been fairly widely used, and they are the only thing we currently have that makes application of the precision guidelines practical for the average editor. ―Mandruss ☎ 10:56, 28 January 2018 (UTC)

• Dude, your math is wrong. There is no need to try to blind us with BS. As I stated in the edit summary, at 45 deg N, 0.1" spans 2.2 meters. This is smaller than the margin of error of the mapping services, as can be seen by switching between Google and Bing. Your made-up thing is overprecise by many orders of magnitude. Abductive (reasoning) 19:16, 28 January 2018 (UTC)