1 million buildings in Los Angeles

Posted by manings on 19 July 2016 in English (English)

Part of our series of diaries sharing experiences on the ongoing LA Building Import into OpenStreetMap. Last month, we talked about the tools. Today, it’s all about the data.

Just last week, we’ve hit 1.1 million buildings imported in LA City!
A great milestone as we are in the final stretch of import, validation and clean-up for LA City. Here’s a few map-shots on what happened in the last couple of months.

What happened?

We made sure that the import process followed the community accepted guidelines. Instead of importing everything with scripts/bots, we used the Tasking Manager to allow volunteers to take part. We divided LA City into four TM projects and organized mapathons within LA City to kick start the process. The animation below shows the weekly progress starting from Southside all the way to SF Valley. Large chunks of buildings were added during and after every mapathon.

Weekly progress, March - July 2016.

We asked volunteers to use a dedicated account and over 100 usernames participated. You can see this checkerboard pattern when you color the buildings by username/id.

Colored by user ID, > 100 usernames.

Before the import, a lot of buildings already exist. In recognition and respect to the mappers before us, we made sure that existing buildings were properly merged/conflated (in JOSM, we use the Replace Geometry tool). This is a tedious process but this is how it should be done. By doing this, we are keeping the editing history of existing buildings.

Feature version. Blue = v1 to Yellow > v4.

What was imported?

Aside from the good quality of building footprint, we included several tags that describes every building. This is not visible in our default map rendering, but these tags exist in most of the data we imported.

Building types

We’ve included building types based on LA Country’s Assessors information.

Colored by building type.

Year the building was originally constructed

There’s a lot of history in the urban expansion of Los Angeles starting from the pueblo in 1700s up to today. The import data has a year_built attribute which we included in the import. You can now see the city’s settlement history in OpenStreetMap.

Colored by year built, 1800 - 2015.

Building heights!

Rendered in Mapbox gl-js

These are a few of the tags we’ve added. I’m excited to see what the community creates out of this data. Our friends at MaptimeLA started experimenting with the data already!

cm0fn3_vyaaws-x jpg_large

Photo by MaptimeLA.

Are you planning on using this data in your own map? Catch the team this weekend at the SOTM-US and show us what you created!

More info about the import is available in the following links:

Location: Jefferson, Los Angeles, Los Angeles County, California, 90089-0871, USA

Comment from ElliottPlack on 19 July 2016 at 15:21

Great work so far!

The building heights are especially cool. Do you know of any documentation or tools to use newer data to update building heights for existing buildings? This would be cool to do elsewhere.

Also, thanks for pointing out the replace geometry tool. I didn’t know that existed.

Comment from kucai on 20 July 2016 at 01:44

Impressive! as darth vader would say..

How fast does the map load in osmand on lower spec android? Still usable?

Comment from Omnific on 20 July 2016 at 04:43

Awesome work! So is there a plan in place to get the addresses imported at some point soon, as that’s hugely critical to the usability?

Comment from CloCkWeRX on 20 July 2016 at 11:52

start_date might be a bit better than year_built, though a lot less intuitive (

Comment from manings on 21 July 2016 at 15:16

@ElliottPlack, We don’t have specific tools other than replace geom and Auto-tools. But definitely a good conflation tool/workflow is necessary. We have good use cases now to specout how to do this. Also, there’s a planned import of building height in SF. Will watch this and learn.

@kucai, I have not downloaded latest map data for OSMAnd, so I can’t say for sure.

@Omnific, Definitely on the radar, but we are still investigating on a good workflow. So far, we are focusing on buildings. Suggestions welcome!

@CloCkWeRX, Sorry, I should have made that clearer.

Comment from devolved_imports on 6 August 2016 at 20:54

F’ing Awesome! I would have to have done more, but it was a great intro to team-based mapping! I’ll keep an eye out for other LA projects.

Login to leave a comment