[OSM-dev] visible-Flag in PBF

[Peter Körner]

Hi

I'm working heavily with the full-history-dumps. Lately I wrote a 
splitter [1] that allows splitting the full-history-dump into smaller 
extracts and I plan to publish some of the extracts on a GWDG mirror.

Right now the splitter uses osmium as Framework, because its xml-reader 
passes the visible-flag along through the pipeline. The xml-writer I 
wrote for osmium [2] is also able to write the visible-flag out.

But actually it would be nice to let the whole xml-bz2-thing be and use 
our new cool pbf stuff. But unfortunately the pbf format does not 
support saving the visible-flag, which is really important when working 
with the history.

I talked with Jochen Topf about the extensibility of out pbf-format and 
he anticipated problems with the DenseInfo message. So my questions are:
  - is it possible for an app like my splitter to add a boolean
    visible-flag to nodes, ways and relations in a pbf file, so that
    other apps like osmosis can still read the generated pbf file (just
    ignoring the visible flag)

  - if not: is it feasible to release a new version of the pbf
    definition, that contains a boolean visible-flag

  - if not: how could a pbf-file generated with the visible-flag but
    incompatible with common apps like osmosis be named, to clearly show
    that it's NO .osm.pbf file? (eg. germany.hosm.pbf or
    germany.osm.history.pbf or ..)

Peter


[1] 
<https://github.com/MaZderMind/OpenStreetMap-History-API/tree/master/splitter>
[2] <https://github.com/MaZderMind/osmium/tree/xml_output>