A Simple Way To Geotag Your Tiddlers And Reasons For Doing So

#1

Consider the level of detail in your coordinates you require. If you need the tiddlers that refer to a general area, for example a city you’re visiting: Panaji → Your Geotag Tag would be “Panaji”. If it’s concerning a trip to Western India, then “Western India” would suffice.

Whenever you click on the tag, you’re going to get a list of tiddlers that contain that tag.

Now, I know what you’re thinking: Is that you, Captain Obvious?

If you want to level up your game, you can use an actual geotag. If you don’t know how to do so, it’s easy. You can use Google.com/Maps or OpenStreetMap or any number of mapping services. You can obtain the coordinates from the address bar or by clicking on the map or by using the side menu (in OSM).

Singbal’s Book House:
OpenStreetMap: 15.498488/73.828645
GoogleMaps: 15.498529330250008, 73.82870627116287

Vijay Amruttulya Tea
OpenStreetMap: 15.500235/73.829750
GoogleMaps: 15.50031613071635, 73.82975524879276

Rather Decent Restrooms:
OpenStreetMap: 15.498793/73.825180
GoogleMaps: 15.498806763081339, 73.82510139544686

At this point, you might realize that if you were to simply create the tags from the coordinates, you’ll just end up with different tags that have no relation with one another.

Here are the three coordinates again with some detail taken away:
15.498488/73.828645 → 15.49/73.82
15.500235/73.829750 → 15.50/73.82
15.498793/73.825180 → 15.49/73.82

The book store and the restrooms would have identical tags, but you’d be missing the tea room. To get around this problem, you could give all of your tiddlers an additional tag with even further detail taken out:

15/73

So, if you’re travelling to the area, you’ll have all your tiddlers ready.

Yesterday, I borrowed some books from the library. I also visited three different government offices. I made 4 tiddlers and geotagged them. I’m going to one of those government offices again, in a couple of weeks. When I check the tags, the library visit will also come up. Oh, I could return the books on my way! You see, the library and the government office would not have a common tag otherwise.

I intend to post further on this thread and include more applications.

AlfieA

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#2

FYI: I researched the use of what3words for this and noticed what was missing was a floor or level. So for example you could point to a shop in a shopping centre but not indicate what floor it was on. I dont recall how but I found a way to add to the “address” a way to save the level eg “L2”.

Also it would be interesting to know the size of the circle when one reduces the detail in a GPS address.

#3

Ah, yes. The government office in question was on the second floor. I don’t see why I couldn’t add: -SecondFloor the tag.

What3Words would make a great tag for a very specific location. If you wanted to increase the grid size, you could add all the sets of three words as tags.

The size of the circle would be the size of the grid. I have found that in most of the relevant (to me) regions of the world, going down to two decimal places puts you within a certain part of town. And a further two decimals will give you nearly the precise location. Another two places and you’re down to millimetre precision.

#4

that is a resonable choice . However you may want to add other details eg door to north, top of the hill…

#5

You might find this useful: TiddlyTools/Widgets/action-getGPS.js

It defines an <$action-getGPS/> widget that uses your browser’s standard navigator.geolocation functions to retrieve GPS data from your device. If your device doesn’t have a built-in GPS radio, it uses an approximate location based on a nearby WiFi or cellular location, or uses “network interpolation” based on your current IP connection.

The widget has the following optional params:

mode    = keyword: get, start, or stop (get)
tiddler = name of tiddler to store GPS data ($:/state/GPSData)
digits  = maximum number of decimal places to retain (6)
age     = maximum age when GPS data must be re-acquired (10000 msec)
timeout = time limit before invoking error handler (15000 msec)
highaccuracy = if "yes", use device sensor, not just WiFi and network location
actions = wikitext/action widgets to invoke after GPS data is received (`actionTiddler` = tiddler title)

When invoked, it writes a JSON tiddler containing the data received from the browser navigator.geolocation.getCurrentPosition(...) function. This data includes at least latitude and longitude values, and may also include altitude, accuracy, altitudeAccuracy, heading, speed and timestamp.

Note that timestamp is a “Unix time” value (milliseconds since January 1, 1970, 00:00:00 UTC), which can be converted to a readable date/time string using the format:timestamp[...] filter operator.

To see the results, try the following in your TiddlyWiki:

<$let tid="MyLocation">
<$button actions="<$action-getGPS tiddler=<<tid>>/>"> get GPS</$button><br>
results = <pre><$text text={{{ [<tid>get[text]] }}}/></pre>
location={{{ [<tid>getindex[latitude]] [<tid>getindex[longitude]] +[join[, ]] }}}
timestamp={{{ [<tid>getindex[timestamp]format:timestamp[MMM DDth, YYYY 0hh:0mm:0ss]] }}}
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#6

ChatGPT responce: Assumed correct as internaly consistent

Good question — the number of decimal places in a GPS coordinate (latitude or longitude) directly affects how precisely that coordinate identifies a point on Earth. Each extra decimal place roughly divides the previous uncertainty by 10, so we can estimate the size of the area or circle it represents.

Here’s a table of approximate ground precision per number of decimal places:

Decimal Places Approx. Precision Area Represented (circle radius) Description
0 111 km ±55 km Country or large region
1 11.1 km ±5.5 km Large city or district
2 1.11 km ±550 m Town or village
3 111 m ±55 m Small neighborhood or block
4 11.1 m ±5.5 m Street or building level
5 1.11 m ±55 cm Individual building or large room
6 0.111 m ±5.5 cm Room-level / precise GPS device
7 0.0111 m ±5.5 mm Survey-grade or differential GPS
8 0.00111 m ±0.55 mm Sub-millimeter precision (beyond civilian GPS)

Explanation

  • Each degree of latitude ≈ 111 km at Earth’s surface.
  • Longitude degrees vary with latitude (shorter toward the poles), but near the equator they are also ≈ 111 km.
  • Each decimal step divides the linear resolution by 10, so the covered area shrinks by roughly 100× (since area scales with the square of radius).

Example

Let’s say your location is:

-33.8746°, 151.2048°

If you round it:

  • to -33.87, 151.20, your uncertainty circle is ≈ 1 km radius.
  • to -33.8746, 151.2048, your uncertainty is ≈ 11 m.
  • to -33.87460, 151.20480, it’s around 1 m.
#7

Some of those descriptions are bonkers. 6 decimal places being an area of ±5.5cm is plausible, but I wouldn’t describe that as “room-level”. More like “point to the corner of a book laying on a table” level.

So I’ll trust XKCD here, plus it’s funnier (even if it misses the 6 decimal places precision)

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#8

It needs to be pointed out that there are limitations to the geotagging approach.

So, I’ll admit that it is better to have a “named” geotag or to follow a similar method as TW_Tones has pointed out with W3W, using a specific location to represent the area in general.

#9

I do think it depends on context. if you have digitised the address already then make full use of it. One oif the key values of W3W is if you want to;

  • get simple names for places
  • Tell someone a location over the phone
  • Only be as precise as needed.
  • Make a tiddler or website, for a place (because a name can be found)