Display of Hidden Lines - Concrete Components

[Jos Arpink]

Looking for some feedback with respect to the display of hidden lines for concrete components.

Here's a simple case (make sure your view's "discipline" setting is "structural"):
In plan view, sketch a concrete slab over a couple of concrete beams.

The beam's top surface and the slab's top surface are co-planar. The beam and slab are monolithic and I would expect to see the sides of the beam "hidden" as a soffit feature of the slab.

In Revit Structure, the beam is represented as a solid line and becomes "hidden" only when I physically drop the beam to a point below the top of the slab. At this point, I'm having to compromise the model to achieve a graphical effect. Furthermore, the beam continues to show up as "hidden" even when I drop it down to a point well beneath the underside of the slab. At this point I don't want to see it on my slab at all, as it missrepresents the support condition of the slab.

I think there's a disconnect between the graphical representation and modelling of this condition.

Thanks in advance for any thoughts or comments.

[Tom Weir]

Jos,
Since the top of the beam and the slab are co-planar it seems to me that Revit Structure is showing the real condition. In order to display that condition the way you want you will need to use the linework tool to make the beam lines appear hidden.
In section you can use the Join Geometry function to show the beam and slab monolithic.
As for beams appearing that you do not want to see you will need to adjust the view range parameters for the bottom of the primary range and the view depth levels. Make them high enough so that the objects are below those ranges

Hope that helps,

Tom Weir
Los Angeles

[Jos Arpink]

Thanks Tom,

Using the linework tool certainly goes a long way towards giving us the kind of control we need over appearance. That helps a lot.

To the Revit developers:
This introduces a manual "drafting" step in achieving something that, in my experience, is fairly standard presentation across the industry. In fact, it's a basic rule of orthographic projection. In the same way that Revit is able to affect the appearance of lineweight, color, and pattern in a cutting plane vs. projection, it should be able to do so for lines that are hidden.

As there is no mention in the on-line help of having to use the linework tool to affect the display of hidden lines in concrete components, I can't help but think that this is not the intended best-practice. I'd like to hear some feedback from the developers on this.

Thanks

[Tom Weir]

Jos,
One of the develpor's efforts of late has been to have us make the foundation plan a hidden line view rather than wireframe. With that anything below the slab will show as hidden line. But I am not sure of the results in your case where the beam and slab are co-planar. Maybe you could test that out and let us know.
What if you kept the bottom of beam at the correct distance below the slab but moved the top down a little so that it would show hidden?

Tom Weir
Los Angeles

[Jos Arpink]

Thanks Tom,

Yes, there are 2 clear conditions here:

One is the display of hidden lines for elements that are discrete but beneath one another, such as footings beneath a slab on grade. Revit seems to handle that well enough.

The other is the display of hidden lines for elements that are co-planar and monolithic, such as concrete beams and slabs. Revit doesn't represent that in accordance with basic rules of orthographic projection. I'm hoping the developers are listening.

For the latter, I'll continue to resist any solution that requires 'tricking' Revit into displaying a hidden line, such as slightly dropping the top of the beam. I'll use the linework tool as a workaround for now.

By the way, do you post here as well as in the autodesk newsgroup? Not sure which is better in terms of getting the attention of the developers? I'd like to think they monitor both with equal diligence.

[Tom Weir]

Jos,
I agree with you that such basic structural situations should not need "tricks" to display correctly. But they have worked hard on this issue and we are getting closer to what we want so have patience.

The Revit Structure forum is a brand new forum, obvioulsy because the product is new, but I have been posting on the AUGI Revit forum site since I started on Revit 2 years ago.

I am hoping this forum will become the central forum for Revit Structure. This has always been the premier forum for Revit, and I hope we can all keep that going

I am beta tester for Revit Structure and am President of the Los Angeles Revit User's Group. I also just completed writing the courseware for Revit Structure Essentials for Autodesk which is just coming out now. Believe me I have the ear of the developers! And I am happy to answer as many questions as I can.

Have a great day....

Tom Weir
Brandow & Johnston Associates
Los Angeles
.

[Wes Macaulay]

Tom, you rock. Thanks for your help on these forums... it's nice to have great input from the structural engineering world here as the next engineering discipline is brought onto the Revit platform.

There are a lot of graphical challenges that Revit has to face, and architecture and structure pose some of the most challenging I'm sure.

[Tom Weir]

Thanks Wes,
Same back at you....your posts have always been very informative and interesting. Since I began on Revit the forum has been my saviour on many occasions. I tell everyone about whenever I get the chance.
I hope we can get the Structural forum to be as dynamic as the Revit building forum as new users come on board.
AUGI rocks!

Have a great day....

Tom Weir
Los Angeles

[Jos Arpink]

To share one more observation on this subject, the Rectangular Footing family included with Revit Structure 1.0 uses a clever trick to display hidden lines in plan view: Two coincident extrusions each with different object styles and materials, one whose visibility is set for plan only (hidden lines), the other everywhere but in plan (solid lines).

I thought I might create a beam family using this approach and it works to the extent that you don't have to join 2 beams together, at which point the distinction between the coincident extrusions is lost and we see both in all views. Same happens to the footings when you attempt to join them together.

Oh so close...

[Wes Macaulay]

That is interesting. I guess Revit joins both solids in the families together with the solids from the other family. They should expand the functionality so that only the visible solids get joined - that would solve this problem.

Nice to see you taking apart the software Jos :-P Nothing better than getting under the hood and seeing how they wired this thing