[OSM-talk] Converting buildings from nodes to ways

Dave F. davefox at madasafish.com
Wed Dec 29 21:13:13 GMT 2010

On 29/12/2010 20:17, andrzej zaborowski wrote:
> Hi Dave,
> On 29 December 2010 21:04, Dave F.<davefox at madasafish.com>  wrote:
>> On 29/12/2010 17:30, andrzej zaborowski wrote:
>>> On 29 December 2010 13:47, Dave F.<davefox at madasafish.com>    wrote:
>>>> On 23/12/2010 12:10, Laurence Penney wrote:
>>>>> I've been 'exploding' several building nodes into ways,
>>>> City centres maps look so much better with polygon ways, don't they?
>>>> To encourage this practice it would be useful if the R (replicate) key in
>>>> Potlatch worked from nodes to ways. It could also copy the history.
>>> There's no way in the current database schema to copy history from
>>> nodes to ways.
>> Hi andrzej
>> Could you elaborate on this please?
>> If you mean it can't currently be done, then yes, I know, that why I was
>> posting the email.
>> If you mean it can't be implemented in the future, then that's a bit
>> disappointing. As OSM increases it mapping detail it would be a very useful
>> addition.
> It could be implemented in the future but the request should not go to
> Potlatch authors because the issue deeper.  So as far as I know the
> workings of OSM, it'd have to wait to at least API 0.7.
> Object history is attached to an object.  Currently objects are
> referenced by id + object type and IDs are not unique accross types
> (node, way, relation).  So the type is a property of an object, not a
> property of a revision of an object.  Thus no object can go from one
> type to another without losing the history.

I'm not sure if non unique ID's would be a problem as the user is 
selecting specific entities to copy from & to .

Lets take a node element of a hotel that's been edited 4 times.

Someones remaps it as a polygon way & copies the tags & history with the 
R key.

The new way entity would only have to store the id tags of the node as 
historic ie "this used to be a node entity with the the id of XYZ123" 
whilst keeping the id it was given when created.

The other tag attributes such as amenity, name etc could be copied 
directly with no problems

Dave F.

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