Grids, levels and working planes

Step 8's frame was presented to you already built. In this step, we'll look at the very same frame built the way you'd build it yourself. We'll set it out from a structural grid of three lines each way at 6 m centres and a run of named levels at 0, 4 and 8 m, and draw it on the orthographic working planes that let you work in plan or in elevation inside a 3D model. Along the way, we'll meet the tools you'll need as soon as a model has more than a handful of members, such as box and lasso selection, bulk editing, saved selections and colouring by section.

There's no new theory in this step. Instead, we'll look at a modelling habit that becomes more important as models get bigger. That habit is checking a built frame by its totals before you read anything finer.

1.0 Setting out a frame

Every real building is set out from a grid. The lines run one way with numbers and the other way with letters, so that a column is "the column on C2" and a beam runs "between A1 and A2 on Level 1". The floors are named levels at known elevations. If you've ever read a general arrangement drawing, this will be second nature to you. The point of bringing the same scaffolding into the 3D canvas is that you then draw the structure where it belongs, by clicking on named points, rather than typing coordinates into a table and hoping you've counted the storeys correctly.

The 3D editor's Grids panel, on the right-hand rail, holds both halves of this. Levels are named elevations. You can add a run of storeys from a base elevation and a list of storey heights (2x4 is the shorthand for two storeys of 4 m), or a single level at an exact elevation, and each one draws as a translucent plan with a name tag at one corner. Structural grids are labelled line systems in plan, with numbers one way and letters the other. The spacings are typed in the same shorthand ( for two bays of 6 m), each grid has its own colour, and you can edit the labels inside the end bubbles. A grid generated from an origin, a rotation and its spacings keeps its generator, so you can it later if the bay sizes change.