Building outline separation

In some cases, there are more than one buildings included in one marked area. Should this not be three separate outlines?

1 Like

If you know exactly, where one building ends, and the other one starts, then: yes, separating them is better than keeping them as a single building. But since a lot of buildings are copied from satellite images, and these used to be pretty bad back in the days, they were very often mapped as a single building instead of 3 separate ones.

Hi, I would agree that there are three buildings here joined by party walls. Thus if possible the three buildings ought to be mapped as separate features. Remember, however, that many older town center buildings are dual purpose having upper floors for residential use with a business use usually on the ground floor. So it might not be correct to tag the whole building as the business. It’s common practice to map the business as a node within the building.

Thanks for your feedback. And thanks for answering in advance what would have been my next question (whole building or node tag). I’ve been searching all over the forum for that answer. Your way of putting it was definitely the most straight forward and clearest.

I have spent considerable time last night trying to outline the three buildings, but abandoned my efforts in the end, because I wasn’t happy with the accuracy I could do it with. I already have a picture of the house fronts and took a quick snap of the back of the houses while I was in town yesterday, but I still found it impossible to do the outline based on the satellite image. Bing and Esri looks very much alike (and too blurry), while Esri (Clarity) Beta is a complete blur. But what really throws me off is the angle of the satellite image. Some seem to have used the roofs for an outline, but that puts these houses half way onto the footpath. This wouldn’t make much difference when outlining one-off houses in the countryside, but it makes a difference in a town, where everything is joined up.

Hi, I understand your frustration in trying to map exactly. This is an almost impossible task. What folk tend to do is map to their best ability, this is often pretty good, though sometimes quite rough. The roof outline is the best place to start on buildings, as this is the line seen from overhead imagery. Then move the roof outline to as best you can line up with the building footprint. Judging from the GPS data the Bing and Esri imagery seems to be fairly accurately lined up. Also, remember that most building corners are square, so if it looks square, make it square. That’s about the best you can do.

I’ve drawn the buildings as per my suggestions, what do you think, OK or not? It’s done in this changeset which I can revert if you wish:- Changeset: 153319736 | OpenStreetMap

What you say makes perfect sense.
Why didn’t I think of that? :slight_smile:

I’m sure your changes are fine. You seem to have plenty of experiense. But you may want to add an extension to the middle house (Carroll’s). You couldn’t possibly know there was one. You can barely make it out on the map. If anything, it looks like a yard on the satellite image. This is the snap I took of the back of the houses: