Jonathan Crowe

My Correct Views on Everything

Importing CanVec Data into OpenStreetMap

Last February I imported CanVec data into OpenStreetMap for the first time.

CanVec is a dataset produced by the federal Department of Natural Resources. It’s been made available to use in OpenStreetMap: users have to download the data for a given area and import it into the OSM database.

It’s a great resource, but I’ve been giving CanVec the side eye for years, largely because OSM users had been bungling the imports and not cleaning up the mess they made. To some extent it also encouraged a certain amount of laziness from Canadian OSM users: why go to the trouble of tracing imagery or going out with a GPS if you could just download the data from the Natural Resources FTP server?

That said, most of my complaints were from a few years ago; it’s been a while since I’ve seen a CanVec-induced mess in the database (for example, doubled or even tripled roads imported on top of one another). And between existing imports and the improved Bing aerial and satellite imagery coverage, there weren’t many places I was aware of that I could, you know, try a CanVec import for myself.

Except one.

Hartney, a town of a few hundred people in southwestern Manitoba, managed to fall between the cracks of two swaths of aerial and satellite imagery. It was a noticeably empty patch of a map that was starting to fill up.

It was also the town my father grew up in. I spent a lot of time there as a child. I was, suffice to say, familiar with it. It was therefore a natural target for me to map. But with no imagery and no realistic chance of my visiting there in the near future, I was not likely to do so in the usual manner.

So I imported CanVec data.

It turned out to be a lot easier than I expected. For one thing, I didn’t have to import the entire tile: I could import only the items I wanted. For another, I didn’t have to resort to JOSM or some other application I was unfamiliar with; I could, it turned out, do it in Potlach, the Flash-based web editor I’ve always used, by importing the downloaded zip file as a vector layer and alt-clicking each element through into the edit screen.

But easier still wasn’t objectively easy. I had to figure out what file to download from the FTP server by looking it up on the Atlas of Canada, and figuring out which of the files to import into Potlatch is a bit of a trial-and-error thing. There’s also a bit of a delay before the CanVec layer shows up in your edit window.

In the end, though, I was able to figure it out, with the following results:

Screenshot of Hartney, Manitoba in OpenStreetMap

I practiced good edit hygiene: I created a separate user account for imports (here) and I cleaned up what I edited: I joined road segments so that a road five blocks long wasn’t five separate ways, I straightened a badly garbled stretch of rail line, and I added a couple of points of interest I knew from personal experience.

In the end, I think I’ve left the map better than I found it. I didn’t everything I could have: CanVec isn’t perfect, and I’m not in a position to verify its data on the ground, so I adopted a less-is-more approach, so that I didn’t simply add a ton of data for someone else to clean up. Nor did I add so much that it would discourage a local user from adding more, better, and more up-to-date material.

A positive experience overall. I was surprised.