Hi,
I have downloaded some of my records to give them to our conservation agency. The records have Longitude/latitude-data in the form 515093868148/119770383707. What coordinate system is this, which EPSG? I cannot work with the current download in ArcGIS.
Would it be possible to choose the coordinate system before downloading the records?
Kind regards
Katrin
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51.5093868148, 11.9770383707 (is this the location?)
I donât know what coordinate system but you might read:
âIdentifying an unknown coordinate systemâ
https://desktop.arcgis.com/en/arcmap/latest/map/projections/identifying-an-unknown-coordinate-system.htm
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The data are exported in a comma separated spreadsheet - perhaps you are using a different delimiter?
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how did you download these records? where did you download these records from? please provide an entire example record that you downloaded.
without that information i can only guess that youâre using Excel or some some other program to view the data in a tabular format, rather than viewing the data as raw text. when Excel converts the data upon opening, it will make some assumptions about how the data is formatted. in the US, thousands separators are commas and decimal separators are periods; whereas, i believe Germans will use periods for thousands separators and commas for decimal separators. so if youâre using something like Excel to view the file, you need to make sure you the thousands separator and decimal separator defaults match the format of the iNat CSV file; or else you need to explicity import the file into Excel to allow you to explicitly specify your thousands and decimal separators. see https://forum.inaturalist.org/t/csv-import-does-not-work/38169/13.
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I believe iNat exclusely uses WGS84 as it relies on google maps for all of the mapping functionality and I think thatâs what they currently support.
As others have said it looks like the decimal point was somehow stripped.
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As far as I know, all geolocation data in iNaturalist are stored and exported as decimal degrees. As far as a specific EPSG, I donât think iNaturalist has one - they just accept latitudes and longitudes as the individual observers (or their cameras or other GNSS devices) report them. As most observers just go with their phone camera coordinates, these are mostly WGS 84 (I know the US GPS system and the European Galileo system use WGS 84, not sure about other parts of the world). Assuming WGS 84 for all observations is probably close enough for biodiversity data - certainly within the accuracy of most observational data.
If your only need is for your own observations, you can check the documentation for whatever method you used for reporting the locations.
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iNatâs lat/long-data are stored (and exported) in WGS 84-system, the EPSG-code of which is 4326.
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Where is this documented? Iâve searched a lot of iNaturalist help pages looking for it.
GPS uses WGS84 and the iNat-apps use GPSâŚ
ChatGPT tells this:
vetgedrukte tekst
It irritates me when there is no URL added to the source and now I forgot about it myself
My question was about documentation from iNaturalist as to whether the software specifies WGS 84, not what chatGPT guesses (or maybe halucinates) about the âPresumed datum.â My earlier post in this thread already noted that many observations are based on phone locations which are WGS 84, but this does not mean that iNaturalist uses WGS 84 for all records. As I suggested to the original poster, assuming WGS 84 is probably good enough for most purposes, but this is apparently not guaranteed by iNaturalist.
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Using the the UTM (Universal Trans Mercator) grid. This location puts the location in a ploughed field in Germany, in 2021 at least. (according to Google Earth). Does this sound right?
As others have said, looks like latitude-longitude coordinates, with (excess) numbers and the decimal separator accidentally removed (~51.51, ~11.98).
Not sure which coordinate system(s) is(are) used internally by iNaturalist (it is not mentioned in the âexport observationsâ page), but in my attempts the âLatitudeâ and âLongitudeâ fields of the resulting .csv files are most sensibly interpreted as degrees North and East relative to the Greenwich meridian, in a WGS84 datum.
(On the other hand, the âmapsâ and âsatelliteâ views are displayed using another, infamous âWeb-/Pseudo-Mercatorâ coordinate system - widely used for map services on the web)
As a general rule, when trying to infer a possible coordinate system for data points, it is best to mention the likely epoch and zone of application (century, decade⌠hemisphere, continent, country⌠if known), so that knowledgeable users can try and make sense of number soup.
edit to be strictly pedantic
beware! I read a lot of confusing statements between âwgs84â, âepsg:4326â, âdatumâ, âcrs (coordinate reference system)â, âellipsoidâ, however the words are not interchangeable; âwgs84â can mean either the âellipsoid wgs84â (epsg:7030), or the âdatum wgs84â (epsg:6326) based on in this ellipsoid, or one among several âcoordinate reference system wgs84â (the most common being epsg:4326 indeed â uses 2-D lat-lon axes + degrees for unit + greenwich meridian for origin + sticking these on top of the âwgs84 datum based on the wgs84 ellipsoidâ). I like the epsg:4979 âwgs84â better :)
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@optilete I apologize! I only just realized that your chatGPT reference was actually quoting the iNat API reference for âPOST observations.â My only excuse is that I was replying during iNatâs downtime on Wednesday, so your link
failed, and I couldnât tell where chatGPT got its information.
Iâm still not sure what the API docs mean by âpresumed datumâ, but at least it is good to know that there is a place where iNaturalist actually documents something about the datum.
Also, I just checked a few iNat observations on GBIF, and all have WGS84 as the geodetic datum (even one of my observations where I pulled lat/lon off a paper topo map), so iNaturalist apparently assumes that this is the datum of locations entered by users.
So yes, data exported by iNaturalist does presume that the geodetic datum is WGS84 (EPSG 4326).
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