I would like to do this castle as a simple 3d building:
I have found a nice collection of detailed architectural drawings so making a good model should not be a problem.
However the height values are confusing me. The castle is situated in a lake with gardens, courtyards etc. placed a few metres above the water.
What would be the correct reference point? If I use the water level as a reference point for the height values the walls on the inside will be too tall but if I use the courtyard as reference the walls facing the lake will be too short.
The best solution would be if the courtyards could somehow be rendered a few metres above the water level. Is that even possible without tagging them as buildings?
http://wiki.openstreetmap.org/wiki/Simple_3D_buildings#Height: reference point = lowest possible position with ground contact
In your case the lowest ground level looks to be the same as water level. There is grassy shore coming down to water while also touching the wall. So water level seems to be the reference height. Except it’s going to change every time the moat seasonally dries down and fills up
As for the courtyard, you can tag it either
or maybe both.
http://wiki.openstreetmap.org/wiki/Key:building doesn’t give a definition of a building so it’s up to you.
That seems like the best solution Thank you for the reply.
height doesn’t work here - at least it isn’t defined that way and I’d be surprised to see renderer support for this.
You could do this and add a pedestrian area on top by using the highway=pedestrian + location=rooftop (not yet supported anywhere, afaik).
It’s only correct if there is no ground below the courtyard but some built-up structure, though…