Canada Building Import

Canada is a vast and uninhabited country for most of its landmass. In addition, and unlike many European countries, there is no local OSM community in most of its cities and villages. Imports are therefore often the best way to have something to refer to in OSM, at least for those who have to travel outside the largest cities. Consequently, many building imports were made over time. Below is a list of known imports with a link to appropriate documentation. If anyone is aware of other building imports, or knows about a building import status, please update the information.

Building Imports

Current imports may be governed by detailed import processes that were developed by the community. Failure to comply with these procedures would be considered vandalism and the data could be deleted from the database.

Ongoing Imports

• The Open Database of Buildings (ODB) import - which might include the Toronto import.
• Toronto building import
• CanVec: Buildings and structures (BS) - included in Canvec import .osm files.
• Automatically Extracted Buildings - buildings extracted from LIDAR data along rivers for NRcan

Completed Imports

• Manitoba Lands Initiative Buildings Import
• Ottawa Building Import
• Montreal open data buildings import

Unknown Import status

A lot of mentions about potential/ongoing Canadian imports (buildings and others) are spread all over the wiki. Here are a few links that mention them...

• Canada Import Status
• Potential Import Data Sources

Compatible Licences

All imports must have a licence compatible with the OSM ODbL license. Only the OSMF Licensing Working Group (LWG) can approve a given license - which is time consuming.

Open Government Licence (OGL 2.0)

The data provided by Federal Agencies under this licence are ODbL compatible. However, according to OSMF, the open government data licensing situation in Canada has a very confusing history and the multitude of local licences does not help. Different names (Open Government Licence and Open Data Licence) have been used for licences based on the same base licence. Furthermore, the same name (Open Data Licence) has been used for licences based on different base licences, confusing the situation even more.

Consequently, No OGL"ish" licences can be considered compatible with ODbL unless LWG approval, with the exception of:

• Ottawa Open Data License 2.0,
• OGL 2.0 British Columbia,
• Sunshine Coast Regional District OGL 2.0, based on the above.
• Sunshine Coast Regional District, based on Version 2 of the Open Government License - British Columbia
• OGL 1.0 Regional District of Nanaimo (based on OGL 2.0 BC)
• OGL 1.0 Ontario
• York Region Open Data License
• OGL 1.0 Toronto

Data Quality & Best Practices

Although most imports did not meet all these requirements, the community aims to import high quality data. The scope and extent of following data quality issues will need to be explored and documented more fully, and a plan made to correct or remove bad data from the import. Here are a few considerations regarding building footprints data quality.

Overlapping buildings

No building footprints should overlap except if they are part of a same building. In these cases, inner/upper components must be tagged using building:part=yes (follow this guideline).

To be continued with examples...

Dirty building ways

Building ways representing orthogonal buildings must not have unnecessary nodes (i.e. collinear nodes). Only for ODB, preliminary analysis indicates that simplification could save several hundred megabytes in Ontario alone

To be continued with examples...

Orthogonal building shape

Right angle corners of a building are expected to have a 90-degree angle. Only for ODB, as much as 2/3 of the building footprints may lack properly orthogonal angles. It is difficult to obtain such result using OSM editing tools when some parts of the building do not actually form right angles. Better algorithms do exist, and some seem to be implemented in open source GIS software. However, editing techniques could also solve the problem.

To be continued with examples...

Oversimplified building shape

Some imports have shown oversimplified, poor quality footprints (e.g. Canvec import). Buildings should be accurately drawn, representing the permanent building structure, as it can be seen according to the image resolution.

To be continued with examples...

Proper building footprint location

Depending on the source, the footprint of a building may not always be accurately located. For example, drawing the roof of a building from imagery will most of time result in an offset of the building compared to its actual location (the higher the building, the larger the offset). Similarly, when setting an image offset from an accurate building, one needs to fit the image according to building location on the ground, not the roof, at least when visible.

To be continued with examples...