[Imports] [Talk-ca] Fwd: [Import] Ottawa Buildings & Addresses [Statistics Canada project]

Devon Fyson devonfyson at gmail.com
Thu Dec 22 18:47:58 UTC 2016

Here's are my thoughts on it:

   1. Arn't the building polygons already available? I see large buildings
   <http://data.ottawa.ca/dataset/large-buildings> and the topographic DWG
   file <http://data.ottawa.ca/dataset/cad-topographic-data> which contains
   2. If this
   is still the import plan, it should be gone through and updated.
   3. Should make use of the changeset tags
   Most importantly type and url. For example:

   comment=Import building polygons for Ottawa, Canada. Importing
   non-existant polygons <or> Conflating with existing polygons
   source:date=<date of data. Would be useful when subsequent versions are
   source=City of Ottawa (maybe should include the dataset such as CAD
   Topographic Mapping Data or Large Buildings)
   source:url=http://data.ottawa.ca/en/dataset/cad-topographic-data (not in
   the list, but I made a comment about it here
   source:license=City of Ottawa Open Data Licence 2.0

   I'm not sure if the tasking manager to JOSM pipeline supports this, but
   if not it's easy to copy/paste all the correct tags in one go under "Tags
   of new changeset".
   4. use source:geometry=
   <https://wiki.openstreetmap.org/wiki/Key:source:geometry> instead of
   source= tag. Thus if POI information is later added to the polygon, it's
   unambiguous as to what the source refers to.
   5. I think building replacements (deletions and additions) should be
   done within the same changeset to make it safer. Deleting all the buildings
   first caused a headache the first time this import was attempted and some
   buildings which were of better quality than the import were wiped out.
   6. split into non-existing and pre-existing buildings. Conflating with
   existing polygons will be more difficult and time consuming. Thus it would
   be good to keep that step in separate changesets with appropriate comments
   so it's easier to review each others work, and disagreements can be more
   easily rectified without touching undisputed work. I've noticed other
   building imports have done this where they split the dataset into
   overlapping and non-overlapping polygons by script.
   7. be more specific in the instructions about deciding which footprints
   are added. Will they be compared to background imagery? Sometimes
   <http://www.openstreetmap.org/changeset/44545610> buildings are
   completely wrong (mixed up in their dataset). And picking between existing
   and imported data is subjective, thus more detailed instructions would be
   good to improve quality and consistency between users.
   8. I would also like to see instructions on checking and copying over
   tags in pre-existing buildings which are to be replaced. And discuss how to
   handle offsets. What's the quality of the building survey? Should the
   aerial imagery be aligned to the polygon, or vise versa?
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