[osmosis-dev] WayKeyFilter

[Andrew Byrd]

On 19 Nov 2009, at 07:30, Brett Henderson wrote:
>
> Can you please update the wiki detailed usage page to reflect the  
> new task?
> http://wiki.openstreetmap.org/wiki/Osmosis/DetailedUsage

Done. I noted that it is currently only in svn.

> On this note, if anybody is keen Osmosis could really do with  
> somebody to take on creating a consistent set of filtering tasks for  
> all entity types (at a minimum it appears that relations are missing  
> from the existing set of tasks).  I'm not sure what the requirements  
> would be and I don't do any filtering myself so don't have much  
> experience with it.  I think all existing tasks have a bug at the  
> moment where they don't handle ',' characters in the key names which  
> probably should also be fixed.

It should be rather simple to extend the existing filter set to  
relations. I have little experience with OSM/Osmosis myself, yet the  
task architecture was easy to understand. One thing needs to be  
clarified, though: should entities belonging to entity types not being  
filtered be passed through or thrown away? Currently, the node filters  
pass only nodes through, while the way filters pass non-way entities  
through unchanged. I see the practical reason for this, but it's not  
consistent. Maybe there should be an option to choose between behaviors.

According to the wiki, a tag is a "Key-Value pair of Unicode strings  
of up to 255 characters (full Unicode characters, not bytes)."  There  
is no mention of excluded list separator characters, so if it was  
changed from comma to something else, there would still be a bug and  
it would cause havoc with people used to using commas.  One reasonable  
solution is some kind of escape character (backslash?) for non- 
splitting commas that are in the key name.

It would also be helpful to have a switch to invert filter logic from  
accept to remove, e.g. so you can accept everything with a highway tag  
then remove everything that has the highway=motorway value. This would  
make for a cleaner operation (and command line) than trying to make an  
exhaustive list of every key-value you want to keep.

It would be nice to have comments from users and developers about how  
the filter set should be designed, and once that's clear I think the  
new tasks would show up, since they are useful to a lot of people, but  
not major undertakings.

-Andrew