id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
16948	[Patch] Validator doesn't complain about overlapping buildings because rounding happens too late	GerdP	GerdP	"==== What steps will reproduce the problem?
1. Use Buildings Plugin, draw a rectangular building
2. Select the building
3. Press B again to activate buiding plugin
4. Draw a 2nd building starting at one node so that the two buildings touch at one side.
5. Run Validator
6. Save the data to a file
7. Run Validator again

==== What is the expected result?
Step 4. should produce two nodes which are shared by both ways
Steps 5 and 7 should not produce any warning or informational message
==== What happens instead?
Only one node is shared. 
Step 5 might produce a informational message about overlapping areas
Step 7 probably produces one Warning ""Crossing buildings (1)"" and now two infos about overlapping areas
Same problem occurs when you upload the data and download again. See also
https://www.openstreetmap.org/changeset/64137994
I am not sure if we have two different errors here or not, my understanding is that the building plugin should produce two shared nodes, but maybe it doesn't because the algo which detects whether or not a node is on a line or not should use some delta proccessing to handle the rounding problems caused by the spherical calcs.

==== Please provide any additional information below. Attach a screenshot if possible.
I think the problem here is that JOSM stores the coordinates with high precision and only the safe to file
or upload process rounds the value. A similar problem occured here:
https://josm.openstreetmap.de/ticket/16875#comment:1

{{{
URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2018-10-28 22:27:31 +0100 (Sun, 28 Oct 2018)
Build-Date:2018-10-28 21:33:32
Revision:14382
Relative:URL: ^/trunk

Identification: JOSM/1.5 (14382 en) Windows 10 64-Bit
OS Build number: Windows 10 Home 1803 (17134)
Memory Usage: 1613 MB / 5461 MB (1353 MB allocated, but free)
Java version: 1.8.0_191-b12, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: \Display0 1920x1080
Maximum Screen Size: 1920x1080
Dataset consistency test: No problems found

Plugins:
+ OpeningHoursEditor (34535)
+ apache-commons (34506)
+ buildings_tools (34572)
+ download_along (34503)
+ ejml (34389)
+ geotools (34513)
+ jaxb (34506)
+ jts (34524)
+ measurement (34529)
+ merge-overlap (34664)
+ o5m (34405)
+ opendata (34698)
+ pbf (34576)
+ poly (34546)
+ reverter (34552)
+ undelete (34568)
+ utilsplugin2 (34506)

Last errors/warnings:
- W: No configuration settings found.  Using hardcoded default values for all pools.
}}}
"	enhancement	closed	normal		Plugin buildings_tools		fixed	template_report