Modelling custom handrails

[Boh]

Is there is someone who can give me some advice on the best way to model 3d custom handrails? I come across this repeatedly everytime I do ramps or stairs. The inbuilt handrail, ramp or stair tools don't give the required result for handrails and balustrade so up till now I have been using simple extrudes and extrude along path objects.

 

To meet code requirement typically the handrail needs to be 900mm above the pitch line of the stair/ramp with horizontal extensions at both top and bottom. Using extrudes is not without it's issues. Editing 3d polygons to the correct angle, height is not easy, then the convert to nurbs curves in EAP objects which are even harder to edit.

 

This is the mess I have on one project where I just wanted to perform some simple edits. I think I need to start from scratch as the extg nurbs curves seem too hard to edit.

 

 

Any tricks and tips would be greatly appreciated!!

 

 

[Taproot]

@Boh From my experience, you have the right approach.  One trick / tip I would offer is to create a library of standard components:  Returns, extensions, uprights, etc.  Instead of trying to model everything as one polyline / nurbs, simplify the operation.  That way, your angled rails can be a simple EAP.  Your miters won't match perfectly, as returns will be horiz. and rails will be sloped at 1:12 ±, but it's generally close enough that the error disappears in the line weights.

 

 

[P Retondo]

It's not the answer you want to hear, but I create a NURBS curve for the entire handrail and extrude-along-path.  The system I use is to draw lines at the appropriate height in each elevation, convert to NURBS, draw arcs from above and convert to NURBS, reposition things so endpoints align (you can also join), then compose into a single NURBS.  After extruding, edit the profile and reposition it - in your case, make sure the center of the circle is at 0,0.  Example of a railing created by this method:

 

[Boh]

Thanks @Taproot and @P Retondo for the tips. The main difficulty I had was just editing polys/nurbs in 3d. I like Paolo's idea of creating outlines in 2 d elevations. Just about to dive back into that project now....

 

Cheers

[Boh]

So with your tips I've had some success. However now I have another problem....

Part of the handrail is not rendering in hidden line. It's fine in OpenGL however. See screen shot. Any idea what is going on here? That particular handrail is a closed loop (it joins back onto itself) so I'm wondering if that could have something to do with it.

 

[P Retondo]

My guess is that it's a bug or software limitation.  If I were you, I'd do that unrendered portion as a separate rail and call it a day!

[Boh]

Thanks Pete. Exactly what I ended up doing!

 

In general I have found geometry disapearing from EOP objects in Hidden Line renders, especially when the geometry encludes curved/round profiles. I find I have to enter the profile and make a change like place the geometry on the screen plan or something. That fixes it but only temporarily as the issue comes back. Do you find the same thing happening or is it just me? I'm hoping that the issue will not happen when we shortly move to VW2020.

 

Can I ask one other question? How do you deal with extrusions like this in top/plan views? Extrusions don't look great in top plan as they have no fill. I have been making symbols out of the extrusions with simple polygons in the 2d top/plan component. That way only the 2d is visible in top plan but the 3d visible on other views. What is your method?

 

Thanks

Bo

[P Retondo]

I just jumped from 2017 to 2020.  I haven't experienced the problem you have observed, but I seldom use hidden line rendering and have spent only an hour or two using v2019.

 

The best way to deal with top/plan view with this kind of object is just as you say, to create a hybrid 2d/3d symbol.  A quick way to do that is to convert a copy of your 3d object, either directly to polygons or by composing a convert-copy-to-lines, and applying a fill.

Edited May 5, 2020 by P Retondo

[Taproot]

@Boh Like Pete, I use hybrid symbols as well.  It's pretty quick if you create the 2D part of the symbol by using the 'Covert Copy to Polygons' (hidden line) command while the 3D object is selected in plan view.

 

I find 'hidden line' views to be slow and problematic.  Wall join issues and minor errors in VW rendering create fragments that can require masking or a  lot of time to fix.

I pretty much always use hidden line in combination with open GL textures for elevation views.  The textures help show the geometry even if the line fails.

 

Also - check your Document Preferences > Mesh Smoothing with Crease Angle.  I typically have mine set to 70.

While it likely doesn't apply, if you are having trouble with curves, I have found that tweaking that setting can positively (or negatively) effect the rendered result.

[Boh]

On 5/13/2020 at 5:03 AM, Taproot said:

Also - check your Document Preferences > Mesh Smoothing with Crease Angle.  I typically have mine set to 70.

While it likely doesn't apply, if you are having trouble with curves, I have found that tweaking that setting can positively (or negatively) effect the rendered result.

I've never paid any attention to this setting as I don't use mesh objects very often.