profiling

In my previous post, I made reference to the complications involved in profiles used for lofting…

When you get a little more advanced with this particular routine, you want to be able to adjust your profiles in place, so that you can control certain aspects of your design in ‘real-time’. I’m going to start using a project I’ve been working on as an example of the why, and hopefully describe the how. Let’s start with how a profile can be constructed.

Arcs and lines are a good starting point, because they allow you to come to grips with what it is you’re creating. As lofting tools, they are also quite stable and easily adjustable. Spline by points are also excellent to use for lofting, because they create smooth, flowing masses, which is all the contemporary faaaashin (Melbournite twang inclusive). But they are a little more unstable (this is something I'll post about later). A couple of basic rules:

1. You need at least two splines if you want a solid mass from a profile – you can’t link a single spline head to tail;
2. You need to find some way to constrain them, otherwise you’ll have difficulty in adjusting them if/when you need to.

Constraining spline by points is a tricky business, because you need to have some kind of rig or controller. I dealt with that in two different ways, that were dictated by the stage of the project. Each offered a different way of adjusting, and VERY different level of complexity. Let’s start with the simpler of the two – the 'reference rig'.

It’s shape was determined by site constraints and maximum floor plate size, and it consists of reference lines that are straights and arcs, all drawn on the default ‘level01’ of the mass file. The rig is easily adjustable, can be scaled, stretched, rotated etc etc. The spline by points (model lines) are then ‘drawn’ over the top, and flexes with the reference lines. Additionally, model lines are constrained to the front/back, left/right system reference planes, so that the profile can be positioned at the centre of the collector mass. Boomtown.

This 'reference rig' profile approach is excellent for quick mass studies that still allow a kind of flexibility – the profiles can be constrained to levels within a 'collector' mass, which means that you can control the area and height with relative ease. But what about a more developed design approach? What about adjusting your mass within the project, instead of within the mass environment? For that, we need to look at the second and more complicated profile - the 'parametric rig'.

(note: A general knowledge of adaptive components and how they work would probably be useful at this point…)

In this profile, there is a lot of complication in controlling some very basic, but specific functions of curves in relation to offsets. Simple trigonometry to determine where arcs should begin and finish, very quickly turned into a bit of a nightmare as this rig type was developed. Let’s have a bit of a look…

First of all, the profile required a structure of nested file relationships. It was necessary to have a few flexible nested families that could drive the profile family by providing points that a spline by point could be drawn on - one to control the arcs, and the other to control the straight lines. These are adaptive components, and required a divided surface to be placed on.

The overriding dimensions were length and width, as these would denote the location of the arcs' respective apexes. The placement points for the adaptive components are adjusted by reference lines that are driven by the afore mentioned nightmare-ish trigonometry. Thank sweet baby jesus that adaptive points love nodes.

In a quick overview, you can see how a few parameters can turn a simple ‘diamond’ shape profile with fillet corners, into a wild dance of adjustable reference planes and adaptive component families. Adjusting where an arc should begin and end, in relation to its radius and offset, mean that you need to supply it with this information at all four corners, in order to get it to work parametrically. Then, as with the first example, it’s simply a case of drawing over the rig points with splines by points.

So. That was heavy, and possibly I’ve raised more questions than answered. But what I want to focus on next is why these profiles don’t work – believe me it took a while to get these rigs to function, and I had a lot of questions that I couldn’t find answers to. 

My next post will be about trying to answer some of these questions (hopefully that's why you're here), as well as maximizing the success of profiles, and achieving lofting routines in a more stable manner. Chur.