[Tagging] automated edits seem to remove crossing=zebra drastically

Shawn K. Quinn skquinn at rushpost.com
Thu Sep 17 19:50:27 UTC 2020


On 9/17/20 11:30, Matthew Woehlke wrote:
> On 17/09/2020 10.07, Shawn K. Quinn wrote:
>> On 9/17/20 08:15, Matthew Woehlke wrote:
>>> It's also atrocious because it can *only* be verified by survey. 
>>> As much as we prefer surveys, the reality is that a lot of 
>>> mapping happens just from aerials, where crossings (both marked 
>>> and, in some cases, unmarked) can be seen, but signals cannot.
>> 
>> I have mapped many traffic signals (and, for that matter, stop and 
>> yield signs) based on shadows visible on the satellite photos. If 
>> you look carefully enough (Bing and Mapbox Satellite at least), 
>> they are there. (Local knowledge helps too in some cases.)
> 
> *Traffic* lights I can buy. I am more suspicious of the claim that 
> you can tell whether they have pedestrian crossing signals or not,
> or that you can reliably identify other signage based solely on 
> outline.

In Texas (possibly elsewhere in the US) a crossing is legally considered
signal controlled even if there is only a three-colored traffic light
and  there is not a specific orange hand/white man  pedestrian signal.
Yes, it may differ elsewhere.

> *Maybe* if you get lucky and have a very clear shadow at the right 
> angle, but if you try to tell me you can identify 
> https://www.openstreetmap.org/node/7695704414 (n.b. a yield sign) 
> from a shadow in aerial imagery, I am going to be deeply suspicious 
> ;-).

Are you sure you didn't mean node 42164543 or something west of it? That
one, I'd need to survey or see street-level imagery to be confident
enough to map it. The shadow, if present, is overlaid by another in the
area. Nodes 6393986190 and 6393985684 do have the "shark's teeth" line
used with yield signs (which I did add just now).

-- 
Shawn K. Quinn <skquinn at rushpost.com>
http://www.rantroulette.com
http://www.skqrecordquest.com



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