[HOT] Digitizing Ercis Turkey : Tracing with more precision

Pierre Béland infosbelas-gps at yahoo.fr
Sat Nov 26 16:52:47 GMT 2011

dies38061 wrote on2011-11-26  11:11:56 

> Pierre said on 6 November (http://lists.openstreetmap.org/pipermail/hot/2011-November/001121.html)...
> "When editing with JOSM, I suggest to zoom in up to the level 70-100 meter to trace more precisely. The scale is located in the upper-
> left corner of JOSM editor."
> The imagery will support zooming much more closely; for tracing buildings and way detail, I zoom to 20 m or less.  Yes, it takes more time.

I wanted to insist on the importance to zoom in more closely to trace roads and rivers with more precision. In fact, I also worked at zoom level 30-50 meter to trace ways with FirstLook Imagery. In parts of the imagery covered by clouds, it was also easier to distinguish and trace ways.

When zooming closer than 100 meter, I have seen many ways traced  with FirstLook that where far from their real position on the Imagery (ie. hundred meters away).  There where also ways previously mapped with Bing Imagery that I realigned using FirstLook.

In such cases, I is time consuming to realign existing nodes and add new nodes to the way. The solution I adopted to edit more rapidly while keeping History of edit in OSM Database, was to keep the original way with just a few nodes at the beginning of this way. From there, I was re-tracing completely the way.


Pierre Béland
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