Long hidden Ceiling Height Bug

[Joe.Stott]

This was brought to my attention recently by one of our Revit users who had modelled a bunch of sloped ceilings using a Basic Ceiling type set to specific heights (Scan-to-BIM) exercise. They then realised that they needed to switch to a Compound ceiling so selected the ceilings and swapped types to find that the ceilings jumped in height. Turns out sloped Basic ceilings take their datum height from the highest point where as Compound ceilings take it from the lowest. 

The above pics are the same ceiling simply with its type changed. 

Not sure of the logic of this but i would expect the type ceiling types to use the same datum. 

[semhustej]

It might be a good thing to post this as a Revit Idea.

https://forums.autodesk.com/t5/revit-ideas/idb-p/302/tab/most-recent

Tomas

[RDAOU]

@Joe.Stott 

No Images attached...nonetheless, I was not able to replicate what is happening on your end. Changing type of a sloped ceiling from Basic to Compound & vvrsa did not affect the levels!!!

[barthbradley]

What to bake your noodle?  In RCP View, sketch the planar (e.g. Basic) ceiling's boundary left-to-right and place a slope arrow left-to-right  Sketch a second planar ceiling's boundary right-to-left and place a slope arrow, also left-to-right the same as first one (same values as well).  

[RDAOU]

@barthbradley 

That is not a mystery ...  Clockwise vs Counter clockwise reverses the polarity of not just ceilings but several other elements in Revit... (unfortunately Autodesk did not include that in any manual)

When sketching the ceiling Counter Clockwise, place and check the Slop arrow settings (Offsets at Tail and at Head)...you will notice that they are functioning in a reversed manner (The offset given at tail is applied at the head and it offsets downwards) 

A similar principle apply also reference planes and adaptive points

[barthbradley]

I never said it was a mystery.  I am fully aware of directional properties of planar elements in Revit.  I've written and spoken on the subject quite a lot. 

[RDAOU]

Ahhhh... I see!! so that noodle baking example given in your earlier reply was a teaser to get the audience hooked first? yeah well sorry I spoiled it.

[Joe.Stott]

Ok, not sure why the images didn't come through but lets try again:
[cid:image001.png@01D74782.24C5C3A0][cid:image002.png@01D74782.24C5C3A0]
Hopefully the images are above.
And to clarify, this is a single ceiling created by sketch with one edge set as slope defining (Not using slope direction arrow) - once created I simply selected it and swapped to the second type and it jumps.
I understand the this can occur when sketching it different directions however there was only 1 sketch done in this case.

[Joe.Stott]

Ok, not sure why the images didn’t come through but lets try again:

Hopefully the images are above.

And to clarify, this is a single ceiling created by sketch with one edge set as slope defining (Not using slope direction arrow) – once created I simply selected it and swapped to the second type and it jumps.

I understand the this can occur when sketching it different directions however there was only 1 sketch done in this case.

[RDAOU]

@Joe.Stott 

The Basic Ceiling (one above) has a reversed polarity (regardless if you use an arrow or set the angle at one edge)...try to sketch it again this time go Clockwise (give the same edge the same angle as before), finis sketch then swap with a compound ceiling...you will see that they will align perfectly Bottom of compound to the plane of the Basic Ceiling

[Lachlan-JWP]

I just wanted to test if this was actually a thing or just just an old revit users tale.

          

This was done in the default construction template. Sketch 2 ceilings, Level 1 was sketched counter-clockwise, Level 2 was sketched clockwise. When their types are changed to compound, the height calculation point for level 1 changes. When I edit the sketch after making the change it still looks the same.

Can anyone explain why this happens? Often there is a reason for these things but this has me stumped.