[OpenLayers-Dev] OSM editor

[Christopher Schmidt]

On Fri, Oct 17, 2008 at 09:56:13PM +0200, Eric Lemoine wrote:
> Hi.
> 
> Is anyone aware of initiatives on developing an OpenLayers-based OSM editor?
> 
> I just think such a thing would be great :-)
> 
> We already have an OSM Format, having an OSM Protocol would make sense to me.

It's a hard problem.

OSM is topological -- meaning each 'node' is an item. Editing a
linestring is not editing a linestring -- it's editing the components
that the linestring is made up of.

The current OSM format stores some of the information that you'd need to
actually edit points, but not enough: for example, we don't parse the
attributes attached to a node that we're putting into a linestring. As a
result, if (for example) you were editing a subway line, where the stops
were sharing nodes with the line, and you dragged a station marker, you
would not have enough information to save that node to the server
without throwing away information.

Additionally, if you imagine a street intersection, in OpenLayers we
represent that as two linestrings (seperate). In OSM, if you edit the
intersection, both lines change (because they share the node). However,
this would be difficult to implement in an OL based editor.

I've done a variety of work on editing OSM *attributes* via OpenLayers:
indeed, simply the displaying of data within the OSM website (zoom in,
open the LayerSwitcher, click "Data" layer) is done with OL vectors, and
was originally coded by me. In general, I think this is a valuable
effort to pursue -- especially within the OSM website, where you can
implement things so that you have an easier, attribute only way for
people to name streets, etc. I would say this is a valuable pursuit,
worth chasing down, especially if you're up for a bit of rails-related
Javascript.  

However, an entirely OSM editor would be difficult, and I expect not the
most productive use of people's time. Especially since potlatch -- the 
flash based eitor -- is so competent, and coding for flash/AS1 is very
similar to Javascript: You can probably help improve Potlatch without
much/any flash knowledge, and you wouldn't have to reimplement the base
that Potlatch has gotten down pretty well.
 
Regards,
-- 
Christopher Schmidt
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