Display object centroid

[naoliv]

Like JOSM already display a small + signal in the middle of ways, couldn't it also display the centroid (the same info that we get with Shift+i) of an object (area or polygon), please?

It would be great to use the center/centroid for object alignment or positioning.

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2014-05-31 01:36:44
Last Changed Author: bastiK
Revision: 7193
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2014-05-30 10:27:18 +0200 (Fri, 30 May 2014)
Last Changed Rev: 7193

Identification: JOSM/1.5 (7193 pt_BR) Linux Debian GNU/Linux unstable (sid)
Memory Usage: 272 MB / 1756 MB (79 MB allocated, but free)
Java version: 1.7.0_55, Oracle Corporation, OpenJDK 64-Bit Server VM
Java package: openjdk-7-jre:amd64-7u55-2.4.7-2
VM arguments: [-Djava.net.useSystemProxies=true, -Dawt.useSystemAAFontSettings=on]
Dataset consistency test: No problems found

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[stoecker]

What would that allow, which you can't do when clicking on a way?

[naoliv]

It's not for the ways, but for the areas.
See this example:

How do we know where is the center/centroid of those objetcs? It's possible to trace some straight lines and roughly calculate them, but it's not an easy or fast process. It also won't give us a precise result.
It's possible to see their centroids with Ctrl+i and add a node to this position. But if you move the object, resizes or modify it, you need to see this info again (and move the node again).

It's what I did (with a lot of work) to align the objects of this stadium:

JOSM could display something like this, but using an apropriated symbol and/or color (instead the node that I had moved to their centroid):

[stoecker]

I know what the centroid is. My question was what displaying and handling it would allow, which is not yet possible when handling the way.

[naoliv]

Mainly to align and place/position objects, regardless their shapes (like I had to do with the stadium).

[stoecker]

I think that is a very specific requirement, which does not verify cluttering the display any more with hard to understand data (try understanding as novice what these symbols are for larger or overlapping areas.

[naoliv]

I understand, but it could be an option (disabled by default) to have this symbol displayed or not.

[naoliv]

Another example: I have some runway lengths, widths and the latitude/longitude of their center.
Having this kind of information displayed would allow me to create a node at this location and then align the runway center to the correct location, without needing to trace more auxiliary lines.

[stoecker]

Replying to naoliv:

I understand, but it could be an option (disabled by default) to have this symbol displayed or not.

Well displaying is not such an issue. Very likely this can be solved by a specific style (maybe needing with the help of some mapcss changes). But using it for operations is a bigger task. We don't even do that for the icons of turn-restrictions, which are displayed for a long time now.

[naoliv]

I am fine if this could be done with a style, sure.