[Talk-us] dubious church node

Sat Sep 30 15:21:30 UTC 2017

A little history on GNIS data, and the Board of Geographic Names.

The US Board of Geographic Names manages names for places and features
shown on US govt maps.  They have been using a database to manage the names
across maps and map scales. That database is the GNIS.

The original GNIS data was populated from all text labels shown on USGS
maps.  The most common source was 1:24,000 scale topo quarter quads.  Text
from 1:100,000, 1:250,000 and 1:1,000,000 scale maps and larger were
included.

The stated map accuracy of these scales  (
https://nationalmap.gov/standards/nmas.html ) is approximately

1:24:000        40 feet
1:250,000     416 feet
1:500,000     833 feet
1:1,000,000   1666 feet

The GNIS dataset includes the most precise location for text, when the text
appears on maps of different scales.

An example of the kinds of text on the maps is attached.
[image: Inline image 1]

On Sat, Sep 30, 2017 at 10:46 AM, Brian May <bmay at mapwise.com> wrote:

> On 9/29/2017 11:06 PM, Kevin Kenny wrote:
>
> On Fri, Sep 29, 2017 at 9:33 PM, Mark Bradley <ethnicfoodisgreat at gmail.com
> > wrote:
>
>>
>> In the course of my mapping in the American Midwest, I have come across
>> several small country churches of GNIS origin that no longer exist.  Often
>> there will be a nearby cemetery, but the church facility is gone.  I simply
>> delete the node.  In one case I know of, the church building was converted
>> into a home, so I remapped it accordingly.
>>
>
> Of course, if the cemetery is there on the ground, then it should be
> mapped. But deleting the node for a demolished church is entirely
> appropriate. For a church converted to a private home, consider:
>
> building=detached historic:amenity=place_of_worship historic:name=* etc.
>
> if the building still resembles a church.
>
>
> For any arm-chair mappers out there, you cannot assume the location of the
> original GNIS point is accurate at all, unless you have up to date evidence
> it is. So if you see a church point sitting on what looks like a house in a
> residential neighborhood on the aerial, then either delete it,  mark it as
> a FIXME or leave it alone. The person working for the Feds who originally
> mapped the point may have been miles off.
>
> A few thoughts:
>
> Churches from GNIS seem to be one of the biggest "map noise" features for
> areas I look at. Sometimes the locational accuracy is spot on, church is
> still there and everything is great. Sometimes the church is a mile and
> half down the road on a different block. Sometimes its in the middle of the
> highway. Sometimes in the water, etc. When I am quickly reviewing an area
> and I see a church point in the water or on a road, I usually just move it
> to a halfway plausible location without doing more research. It would be
> nice to have a fairly solid process for reviewing these with external data
> that is of known high quality.
>
> I did a little playing around with the new USGS Map VIewer [1] and it has
> a Structures layer.  This appears to be part of the volunteer corps thing
> w/ USGS, which was (is?) a national program to provide higher accuracy
> points focused on buildings and structures.  I found this [2] from 2012
> that provides an overview. Looks like they intended to contribute back to
> OSM - but no word on that in the doc. Found this site as well [3], but out
> of time to dig into it for now. Anyone know more about this Structures
> layer?
>
> In the USGS Map Viewer, you can click on a structure and see details about
> it. Some say source=centroid - to me this means parcel centroid. Many have
> addresses as well. The map viewer allows you to switch the base map to OSM.
> So then you get a nice QA tool to check OSM features in an area. The
> structures layer doesn't include churches, but cemeteries are included.
> Other features include Post Offices, State Capitol Buildings, Hospitals /
> Medical Centers, Police Stations, Prisons, Colleges, Technical Schools,
> Schools, Campgrounds, Trailheads and Visitor Information Centers.
>
> I have a statewide parcels layer that just shows church polygons and
> labels that I use sometimes use as well for checking churches - others are
> welcome to use it if interested.
>
> [1] https://viewer.nationalmap.gov/advanced-viewer/
> [2] https://pubs.usgs.gov/of/2012/1209/pdf/ofr2012-1209.pdf
> [3] https://nationalmap.gov/TheNationalMapCorps/#
>
> Brian
>
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