OSM History Viewer

Changeset visualisation

With OSM History Viewer, you can visualise the changes that were made in one changeset compared to what things looked like before. It shows all tags that have been removed or added to elements and visualises how nodes and ways have been modified, moved, created or removed. Later it will also be possible to see how a relation was changed in the changeset.

To visualise the changes, all ways affected by the changeset are turned into 'segments', where one segment represents the connection of two nodes. Each segment is then analysed to determine whether it was moved, created or deleted in that changeset. If a segment, or its location only existed before the commit, it is marked red on a map. If a segment, or its location only exists after the commit, it will be marked green. If a segment did not change, it will be marked blue.

This method has the following effects on the visualisation:

• If you moved a way, the old way will be on the map in red, the new way in green.
• If you only move one node in a very long way, only the part that you actually have changed will be marked modified.
• If you split a way or combine multiple ways, they will be visualised as unmodified (blue), as you have not changed their position on the map.
• If you have only changed the tag of a way, it will also be shown blue.
• If you see something brown on the map (green and red mixed together) you might have moved a node only by a small distance. Zoom in to see that the green line will be distinct from red one instead of being at the same position.

This method has the great advantage over the simple displaying of the changeset content that you can see how the objects on the map actually have changed (and not how their data representation in the OSM database has changed).

See also: Achavi#Changeset Viewer – another, similar changeset viewer (linked by WhoDidIt)

Relation Blame

With “Relation Blame” you can find out which part of a relation has been added to it by whom. The relation (including all its sub-relations) is split into segments (segments being connections between two nodes) and then the history is searched for the first occurrence of these segments in the relation. By this you can find out who added a certain part to the relation in which changeset (and then “blame” them ;-)). This segment-based method has the big advantage that people just splitting ways will not appear to have added a way to the relation (even though they technically did). A “wrong” author might still be displayed though if someone added some nodes to a way of the relation (for example by connecting another way to it or by improving its accuracy).

Greasemonkey script

On there is a Greasemonkey script that adds links to OSM History Viewer to the relation and changeset pages on www.openstreetmap.org. That script is currently broken in opera/chrome. Fixed version

Bookmarklet

Use a bookmarklet to conveniently access the Changeset Viewer! By clicking on the new bookmark (or opening it via a keyword) while visiting a changeset page such as changeset 6798641, you will be redirected to the analysis page for that changeset. (Credits to Eugene).

javascript:a=document.location.href.split('/');if(a[2]+a[3]=='www.openstreetmap.orgchangeset'){document.location.href='http://osmhv.openstreetmap.de/changeset.jsp?id='+a[4].split('?')[0]}else{alert('This is not a valid OSM changeset page.')}

Use the following code instead to open the OSMHV analysis page in a new window/tab (allows you to switch between the changeset and OSMHV view):

javascript:a=document.location.href.split('/');if(a[2]+a[3]=='www.openstreetmap.orgchangeset'){(function(){window.open('http://osmhv.openstreetmap.de/changeset.jsp?id='+a[4].split('?')[0]);%20})();}else{alert('This is not a valid OSM changeset page.')}

TODO: One for the "relation blame" feature.