Coordinate accuracy/update frequency?

genthusiast

About a year ago - or I don't know ... a while ago - I noticed FamilySearch mapping changed from another map/content provider to Google maps. So it is my current understanding that FamilySearch uses/embeds maps from Google maps.

If that is the case - why don't coordinates from Google maps within FamilySearch match coordinates from Google maps?

Example:

FamilySearch coordinates for Ensign Peak, Salt Lake City, Utah:

https://www.familysearch.org/research/places/?lat=40.7945&lng=-111.8907&distance=0.12k&includeIsParent=true&mapShowCircle=true&searchTypeaheadInputText=40.7945%2C-111.8907&partial=undefined

Google maps with the same coordinates applied:

https://www.google.com/maps/place/40%C2%B047'40.2%22N+111%C2%B053'26.5%22W/@40.7944463,-111.8908065,61m/data=!3m1!1e3!4m4!3m3!8m2!3d40.7945!4d-111.8906944?entry=ttu

Yes the difference with these particular coordinates are off probably within 30 feet or so - but I am seeing other coordinates that are off much more significantly and am curious what might be causing the differences. Are FamilySearch maps just not adjusted for polar shift - or not updated as frequently?

Thanks.

Gordon Collett

The latitude and longitude in the Place database do not necessarily come from Google. I see many places where the only citation on the place is NGS (I've never been quite sure what the initial stand for) followed by a number. It seems that the original build of the Places database came from the NGS database and I assume the latitude and longitude are those from the NGS database. The only way to update those to correspond with Google is for an editor of the database to go in and manually correct them. I've seen a lot of rather imprecise NGS coordinates. Some of which put places that should be on a coast line out in the ocean.

Then there is the problem of whose coordinates should be used. For Leirvik, Stord, Hordaland, Norway, your choices are:

Google - 59.7807577, 5.4178071

Wikipedia - 59.7798, 5.5005

The Norwegian Mapping Authority - 59.77977, 5.50053

This displayed coordinates in the Places database are: 59.7798, 5.5005 so either the Wikipedia ones are being used or the Norwegian ones are but are being rounded to just four decimal places.

Gordon Collett

Sorry. It's NGA, not NGS.

Also, sorry, it looks like you were talking about something else. Clicking on your link to the database, there is no place marker there. You just put in the co-ordinates for a search.

Looking closely at your links, it looks like the difference is in the coordinates:

Google: 40.7944463,-111.8916273

FamilySearch: lat=40.7945&lng=-111.8907

I looks like FamilySearch rounds to four places. But I'm not sure why the latitudes in the two links you posted are so different.

So to take a closer look, if I start with your FamilySearch Places database link as you have it posted above to get this:

And put exactly those co-ordinates in Google Maps:

And the superimpose the two maps so the marked trails, which are both from Goole match exactly like this:

The place markers match exactly.

It looks like the co-ordinates you were using shifted somewhere and that threw off your results. Do you have another example were the same coordinates show different places?

russellwaltgeorge1

Another reason coordinates may not match, is a Places Editor can change the coordinates. This may be done at the request of a Patron, or just to have the pin better match near the name of the place. Also, if the coordinates are not know of a place, it mabe be assinged to the same as the parent.