[Talk-ca] OSM data quality in Canada

[Steve Singer]

On Wed, 17 Jun 2015, Martijn van Exel wrote:

> Hi Andrew, 
>
> Thanks for elaborating on the CanVec / Geobase imports! This also raises new questions.. See below.
>
>> On Jun 17, 2015, at 3:00 PM, Andrew MacKinnon <andrewpmk at gmail.com> wrote:
>> 
>> A lot of the data in Canada was imported from CanVec and Geobase,
>> some of it by me several years ago. The imported data is pretty poor
>> quality in many places. I haven't done much work on this recently, as
>> imports have a bad reputation in OSM and I am mostly concerned with
>> surveying. For example:
>> 
>> - Some older road data comes from an import which combined CanVec and
>> Statistics Canada road names, attempting to match the road names in
>> Statistics Canada with roads without names from CanVec, and this data
>> is poor quality.
>
> Is this described in more detail anywhere? Are the data / scripts / 
> process still available? Which dat was poor quality, CanVec or Statistics 
> Canada?

The StatsCan geometries were really poor at least as bad as the original 
TIGER stuff but they were the only source of road names in some places.

The scripts used for the geobase->osm (and attaching statscan names) are 
available at 
http://svn.openstreetmap.org/applications/utils/import/geobase2osm
I only did this in Alberta and Ontario.

We tried to use roadmatcher to only include road segments that we were 
pretty sure didn't already exist in OSM.  This often left gaps in road 
segments where roadmatcher wasn't sure if something was or wasn't included. 
Also we didn't have any way of automatically attaching the existing OSM 
ways with the new geobase ways which left A LOT of unconnected roads.  This 
has mostly been fixed (often thanks to keeprite and maproulette) but it 
tooks many years.

Some of the initial sections also didn't connect new geobase roads with each 
other due to a bug the import script, we tried to fix this with repair 
scripts at the time.


Steve