Loft tool -- why do you need it? Define how it would work

[Wes Macaulay]

Many of us have advocated a loft tool of some kind here on AUGI but we haven't been specific on how it should work, or why we would need it on a day to day basis. This thread should avoid discussion of marquee-type architecture like Gehry or Hadid -- why do you need it on YOUR projects?

Then, I think we should define how the tool works so the Factory can look at our requirements for this tool and think about how they'd make it happen.

I'll go first!

Minimum Requirements
Cross Section (Profile) Definition

• The tool should be able to blend lines, arcs, splines and ellipses in cross section
• There should be no limit to the number of cross sections that can be created along the path
• Cross sections could be added to any segment (perhaps toggled in a right-click menu) at the middle of the segment. Like a blend the object would blend in a linear fashion between one profile and the next.
• The profile would be perpendicular to the middle of the segment and perpendicular to the path
• The profile can be rotated, and could be either sketch-based or profile-family based

Path Definition

• The path should allow lines, arcs, splines, and ellipses
• The path should have no limit to the number of segments in the loft
• Initial versions of this tool would probably follow the Revit precedent of being workplane based. Later versions of this tool should be afford users the opportunity to develop the loft in a more freeform manner without always being constrained to a workplane

Applications
We have several uses for this tool already for which we are using workarounds.

• A decorative foam arch (or buttress) which follows a curving path in elevation and increases in size from where it attaches to the wall to where it attaches to the soffit
• Walls which curve in plan and whose top increases in height (there are many examples here on AUGI of others with this exact need)
• A roof with a certain cross sectional profile that turns through 90d and ends with another cross section profile (changes slope as it rotates)
• A tool for making roads (though being restricted to one plane with the path would make this an incomplete solution)

I will post some examples here in this thread/post as examples of why we need this tool and what it would need to do.

[Graham Briggs]

Wes,

This sounds like the heart of a successful and powerful ramp and road tool. I like it!!

Graham

[Andre Baros]

Great idea but didn't we already start this in another thread? I'll dig up some examples...

[Wes Macaulay]

You did have a post in your thread with a poll which had a desciption of how the tool should work:

The Max Loft tool is similar to the Revit Sweep except that you can add multiple profiles along the length of the path. For example, you could draw a path for ductwork and then assign a different size (or even shape) profile at different points along it's length. In Max you can also control the transitions so that you can have a smooth transition from one size to the next (like in the ductwork example) or have steped transitions, such as if you're using it to draw a building mass.

If these transitions are important, then could you describe this in more detail so people can understand it? If you have screenshots then all the better.

I'm trying to create a technical definition for the loft tool that I can present to the Factory.

[Andre Baros]

I'm going to dribble examples into this thread, since I don't have time to write them all up at once:
http://forums.augi.com/showthread.php?t=18676 was indeed the thread where I first tried to make a list.

OK, example 1:
Millwork panels an an arched ceiling, as seen in this thread here:
http://forums.augi.com/showthread.php?t=27054
I needed to take a curved profile over an arch and around a corner. In retrospect, because the profile of these pieces didn't change I could have done this with a sweep along the edge of a void defining the recess in the panel, but at the time, I wanted a loft tool, because I was starting out with a series of drafted sections at key points along the curve. If I were doing this with the Max Loft tool, I would have one curve define the path and three curves define the profile (at the start middle and transition each used more than once).

This was modeled at first just to render it, but ultimately needed to be perfectly accurate to make full size templates for the millworker. Ergo, it couldn't just remain a series of details.

The stone arch here also could have used the loft tool to accommodate the changing depth of the section from vertical to curve... I modeled it the way they would build it, with separate blends for each stone, but would have preferred a single piece of geometry with drafted on joints.

[Andre Baros]

example 2:
Curved Driveway with curbes (I'm sure this would apply to parking garage ramps as well) Simple house on a hill with a slight curve to the driveway... I can't post an example because I still haven't figured out how to draw it...

[DanielleAnderson]

Yes Andre,
The site tools, I believe, are where we would really benefit from a loft tool.
This is what I can see using a loft tool for:

1) Driveways that slope in more than one direction
2) Curbs associated with those driveways
3) Site walls that follow slopes, turn corners and change height all at the same time
4) In my former life, I would have said train tracks (such as elevated light rail structures) would be another useful application as well.
5) We do a lot of interiors work, which requires us to actually model furniture, interior features such as complex woodwork, etc. which would be a great use for a loft tool. We also have to model complicated medical equipment in operating rooms, clinics, etc.

A loft tool would increase the depth and power of a lot of tools we already have but that just need a little extra boost.

[Scott D Davis]

What I read from Andre and Danielle's posts is that their need for a "loft" tool is to sweep a constant profile along a curved 3D path. With a curb, its the same profile, beginning and end. With a driveway, same thing. The need therefore is to be able to "pick" a path that snaps to a topo, and that one can assign a constant profile to.

The other desire for a loft tool is something a bit different, which is to have 2 profiles (or more) swept along a curved 3D path. The resulting form changes shape from one end of the sweep path to the other.

[Scott D Davis]

example 2:
Curved Driveway with curbes (I'm sure this would apply to parking garage ramps as well) Simple house on a hill with a slight curve to the driveway... I can't post an example because I still haven't figured out how to draw it...

If it's a constant slope, you could use a curved ramp with "railing" profiles set to the shape and position of your curb.

[Andre Baros]

Honestly, the more I use Revit, the less I need a loft tool, but there are times... the most common uses are probably furniture and fixtures. I know we shouldn't be modeling all these details in Revit, but sometimes you really want to. If you have a custom door knob, or custom furniture piece, or a custom faucet it's a bit frustrating to have to change to/learn another program to draw it, but then again, it is much better for the big picture.

Going through a lot of the examples from my old files, I now know how to model those in Revit using sweeps where I once thought I needed a loft.

Maybe we shouldn't be wishing for a loft tool and instead be wishing for fixes for the rest. IE, curved walls with a sloping flat top in the wall tools, not as a in-place loft work-around (by simply editing the sketch in an un-folded elevation), duct and pipe tools in Revit Building, etc. ramps which had layers like floors and could connect to floors, etc. More import options and control over imported objects, etc.

At the very least, I still would like a cross of the sweep and blend. Base profile, top profile, path.