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Life Line

Terracing Buildings

Following up from the previous article on addressing flats, in this article we deal with drawing buildings. The new area has lots of similarly looking buildings, and they're not exactly square. They do however all (broadly) share the same shape:

JOSM has a terracer plugin, which allows you to draw a rectangle, and then quickly convert it to a row of terraced houses and at the same time add house numbers to the generated houses.

You do the following steps with the plugin:



Find a spot that needs buildings added

Draw the outline

Add the building=residential tag

Select road and outline, and press Shift-T to run the terracer plugin.

Select every other middle node at the back

Use JOSM's Way Accuracy Tool w to add in the other nodes for the back

Repeat for the other 5 buildings

Select all buildings and use the Orthogonalise Shape tool Q to "square" the buildings.

Having to do step 6 and 7 for every building, especially when there are a lot of them, is a very tedious, and inaccurate process. It is sometimes even faster to draw all the building outlines by hand, select them all, and orthogonalise them.

But the terracer does already save a lot of work, so what if I could make it better and make it support the type of buildings that are common in my new neighbourhood?

I had a look into the plugin, and it seems that I have to use Java to update it. I don't really use Java, and hardly ever written any code in it. It also sadly lives on some SVN repository, so pull requests against it are difficult too. Instead, I pushed my version of the repository to — and called my version Überterrace. Oh, and I learned some Java.

After a while of figuring out some ... syntax issues, and figuring out how to build this stuff, I managed to improve the plugin with another option. The new option is "fancy outline" and automatically draws in the "extensions at the back". The new work flow is now:



Find a spot that needs buildings added

Draw the outline, including the backends

Add the building=residential tag

Select road and outline, and press Shift-T to run the terracer plugin with the "fancy outline" checkbox set.

Drag the selected middle nodes to the right position.

Press Shift-E to select all buildings, and press q to orthogonalise them.

As you can see, this makes it much faster to draw such building outlines. When you look at it in 3D however, you can see there is still a problem though:

The 3D image that is being drawn does not take into account that the "extension" at the back, isn't part of the gabled roof nor that it is only two instead of three levels. There are various possibilities of building layouts:

So the next versions of Überterrace are going to support (some of) these as well!


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You're a hero. You can only imagine the amount of time I spent faffing around with the fancy outlines...

Of course there are other configurations of 'fancy outline', such as the back extensions being on the 'outside' edge rather than meeting on the inside edge. See this area for a muddle of shapes:


@Tom: I know! I'll get to these if I figure out how to make it draw buildings from a template that you draw first, or something.

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