I’m not sure if this is the best forum, but I couldn’t find a better one.
Several Canadian provinces and territories are rather large in the Geofabrik regional exports: Nunavut is 1.2 GB, Quebec and British Columbia are 1.1 GB each, Ontario is 863 MB. Currently there are no subdivisions defined for them, so downloading an export requires getting the full province/territory.
I know some other countries have sub-regions defined below state/province level (e.g. Regierungsbezirke for some German states) – would it be possible to define sub-regions for the bigger Canadian regions too?
Quebec admin_level=5 has 16 subdivisions, that might be a bit too fine-grained, I don’t know if there are also larger subdivisions in popular use? Maybe they could be assembled from several admin_level=5 combined together, or is it easier for Geofabrik if we were to manually draw rough dividing lines?
British Columbia has a couple admin_level=5 + boundary=aboriginal_lands. Admin boundaries are at level 6 and there are 28 of them, which seems like too much to use for data export subvisions. I would suggest a manual subdivision something like: Vancouver Island, Metro Vancouver up to Chilliwack, then divide the rest into northern and southern?
Northwest Territories is 403 MB, it has five admin_level=5
Alberta is 312 MB, it has admin_level=6 for counties that seem a bit too fine grained, a rougher subdivision would probably be Calgary, Edmonton, southern Alberta, northern Alberta?
Newfoundland and Labrador is 245 MB, it has two admin_level=5 (for Labrador and Newfoundland) which would work
The others are under 200 MB and do not have conveniently large admin subdivisions in OSM, so it’s probably not worth subdividing them.
I’m not sure how useful splitting would be in terms of keeping data size down. Just eyeballing it from the map, Quebec has most of its data concentrated along the St. Lawrence River, Ontario in the area surrounded by the Great Lakes, and British Columbia is centered around Vancouver. They’re not like California, where a dividing line somewhere around Fresno will split the state into two similar-sized chunks of data.
As a rule of thumb, I have tried to introduce subdivisions when files
surpassed the 1 GB. I’m happy to look into the larger Canadian
provinces, though the 16 subdivisions of Quebec do sound a little over
the top!
The download server generally only has free shape files for the “leaf
nodes” of the region tree so splitting Nunavut in three will mean the
loss of the whole-Nunavut shape file.
I was thinking of subdivisions like “Montréal and suburbs”, “Québec and suburbs”, maybe Eastern Townships/Estrie, Outaouais, and then two or three subdivisions for the remaining areas. I’m guessing people are more likely to want Laval and Longueuil in one data file than Laval and Val d’Or, despite the Saint Lawrence separating Longueuil. But I’ll defer to Quebecers for subdivisions that make sense to them.
I’m not sure about that. Nunavut is 1.2 GB for 2 million square kilometers, and that’s overwhelmingly natural features (mostly waterways and water polygons, per Taginfo). Quebec is 1.1 GB for 1.5 million sq km, and much of it also has many lakes, so I would guess the natural features to be roughly 700-900 MB, and that’s going to be distributed throughout the area. Hence the proposed subdivision - people who want to work with Montréal’s data won’t need to download every lake in Nord-du-Québec.
Yes, I agree 16 subdivisions is a bit much. How do you split the regions in your toolchain? Does it go off admin boundaries in the OSM data you’re processing? Or do you have the boundaries extracted into standalone polygons before the processing? If the latter, could we provide polygon boundaries for sub-regions manually?
I will admit this hasn’t occurred to me, partly because I’m most interested in the .osm.pbf files. Do you have a way of knowing if the shp files are used, and by whom?