# Skillions

Please share tips how to get them right https://www.openstreetmap.org/relation/12660108

Looked fine in kendzi yesterday, now in f4map one skillion is wrong, OSM2World does not do them at all.

Ich denke das Problem liegt darin, dass along/across keine eindeutige Aussage zur Dachneigung bei â€śskillionâ€ť ist und f4map das deshalb nicht unterstĂĽtzt.
Nutze besser roof:direction=*. Ist nur geringfĂĽgig aufwĂ¤ndger (Mit JOSM kann man den Winkel aber leicht ermitteln).

Hello pyram, along/across is actually honoured, but not, where there is up, where is down (in the bottom part of the staircase building part). I read somewhere, that it may work correctly when I reorder the points on the way. I am missing a clear specification for this though, so that different renderers can show the same.

roof:direction may be very clear if you use 0 to 360 degrees?!

Btw: the result looks very strange, e.g. on f4map. But I donâ€™t know the real intention.
Osmbuilding doesnâ€™t show much â€¦

Here a picture, https://www.ibkinfo.at/media/11877/6-tantegert-1920x1080-300dpi-a.jpg - the staircase is outside of the building and winds up.

Cool, osmbuilding also does the other two skillions turned 180, but the gabled roof is fine f4map does something with the gabled roof, that I do not understand either.

PS: Kendzi rotates the benches, which is nice and others might follow

That is the problem. You can just solve it with â€śroof:direction=(degree)â€ť or keep looking for another solution (which I donâ€™t know)â€¦

This is a coincidence, but not a solution.

Sorry to read that! No, I will not enter arbitrary numerical values for something that is inherently unstable, where the next person that rotates the stuff has to enter all new values; and for something that can be computed to high precision, and as can be seen is already computed to great result, but only missing the information whether the computed value is a positive or a negative one.

A pity that there is no reference implenentation, that might make up for a missing specification. OSM Buildings is open source, maybe dig a little there.

PS: No luck searching osmbuilding - https://github.com/OSMBuildings/OSMBuildings/blob/55e22a6d09911550225625d1c87a87bf8260f6b9/src/triangulate/roofs/index.js#L135 - this translates to me â€śif the skillion roof has no direction, then it is flatâ€ť, which is not what I observe on the web mapâ€¦

PPS: No wonder the skillions appear in the viewer, a value for roofDirection gets passed from the server to the in browser viewer with the objects in the scene. So, the value seems to be calculated somewhere else, not part of the available source in the github organization that hosts osmbuildings. CF https://github.com/OSMBuildings/OSMBuildings/blob/master/docs/server.md

There are 2 possible values for roof:orientation. But a rectangular skillion roof has 4 possible orientations (unlike a simple gabled roof, which only has 2). So roof:orientation isnâ€™t suitable for mapping skillion roofs.

OSM2World does snapping for roof:direction so you donâ€™t need to enter a super-precise value. Even a cardinal direction such as â€śNWâ€ť would be enough. (Snapping of roof:direction is something that doesnâ€™t work in all renderers, unfortunately.)

Snapping to local reference frame is a nice feature, the values become much more stable, perhaps enough so to be useful in real world usage, unlike mine, which is a toy scenario - thank you for the hint! I even tried that with kendzi at first, but there sadly N is in the global frame, so I dropped directions and would have missed the feature. Letâ€™s have a look at what the other contenders do!

UPDATE f4map: A day later, direction NE of the skillion obviously means global NE, not orthogonal to the buildings private frame, which before was perfect, if it was not for up/down direction.

UPDATE OSM Buildings: One half day later updated too; here also cardinal is degrees without snapping to local frame, additionally seems to now mistake orientation for global orientation? Additionally, openstreetmap.fr does not send CORS header, so no backdrop anymore, just black space - map was there yesterday though!

Hi guys, use PlugIn improved Kendzi 3D: you can see there preview betterâ€¦