# What is the difference between "height" and "building:height" keys?

You already posted a scheme for the building part with
min_height = 8
height = 16
roof:height = 8

Now try to draw a similar scheme for
height = 16
roof:height = 8
(no min_height)

and for the building part
min_height = 8
height = 20
roof:height = 8

Take any roof shape you like for this task.

Hm, I do not know how to solve either of these two tasks:

In your first diagram, ? is min height, which is height - roof height.

In you second diagram you have two objects, each with their own height, roof height and min height, so there is more than one “?”.

min height for the lower part is 0 and min-height for the upper part is its height - its roof height. It looks like roof height for the lower part is zero.

bernard1995:

Hint 1. Walls where you placed the question mark!

Hint 2. A building part doesn’t have anything below *min_height *.

For the first task min_height = 0, because it’s not provided

The second task defines only one building part, so the lower part must be deleted.

I do not understand. So these walls are part of the dome roof too?

?

Why don’t we have walls now, like we do in the Case 1?

building:part by definition defines a building part with walls and a roof. So the walls are always there!
Again, building:part is both walls and a roof!

The height of the walls is equal to height - min_height - roof:height.
The type of roof is defined by roof:shape. The roof is assumed to be flat if roof:shape isn’t set.

If the the height of the walls (height - min_height - roof:height) is equal to zero, the the building part doesn’t have walls and has only a roof.

Got it?

Thank you vvoovv! I guess I do.

Neither building:part nor Simple 3D buildings wiki pages mention anything about upper two quotes.

1)
building = yes
height = 16
roof:height = 8
roof:shape = dome
(no min_height)

bulding = yes
min_height = 8
height = 20
roof:height = 8
roof:shape = dome

There is nothing to read besides Simple 3D buildings

I understood this part:

As: a building:part consists of walls and the roof above those walls.

These examples are different from the previous, as now we have: ‘building=yes’, while with previous ones we had ‘building:part=yes’.

Can it be said that similarly with ‘building:part=yes’, the ‘building=yes’ is by definition also consistsed of walls and the roof above those walls?

Correct.

I added building=yes, because building:part can’t exist without being enclosed into *building=**.

The same rules applies to a building if it doesn’t have any building part inside it.

A question (another one, sorry):

Which same rule? This one:

?

What happens if a building (outline) has at least one building part inside it?

You wanted to say, that regardless of whether a closed way has a building part(s) inside, it (that closed way) always has to be tagged with ‘building=yes’ in order to be considered to be the building (outline)? Is that it?
If it is, then I apologize for my stupid question.
If it is not?

As for the Simple 3D buildings article: I somehow have a feeling that is very short. I am not sure who wrote it, but it definitively needs to be extended.
In the last couple of topic on this forum, I learned more from your, escada, hadw and R0bst3r and other users replies then by reading that short article.

We even found out that there is important information which is not included in any wiki.openstreetmap article, let alone the Simple 3D buildings one.

Please do not take this reply as offensive, nor my intention to act as a ‘smart-ass’. I am very grateful for your free time, knowledge and patience. I am just trying to learn something, and I am getting frustrated with the lack of articles/learning material. That’s why I am trying to ask all these picky, or stupid-sounded questions.

Does upper quote apply to building outlines as well (tagged with: ‘building’)?

So both a building outline (tagged with ‘building’) and a building part (tagged with ‘building:part’) consist of walls and the roof above those walls?

Exactly.

Thank you vvoovv.
Can I again try to solve the previous two examples you gave me?
For the start, the first example:

You told me previously that:

So this is it:

?

So we know that there are walls beneath the roof, because min_height is equal to 0 (it’s not defined therefore it’s equal to 0), and the roof starts from 8 meters above the ground. So this empty space from 0 to 8 meters above the ground is assumed to be “filled” with walls?

Yes.

So the first task is solved correctly.