Introduction
In this tutorial we'll look at how to model a quilted cushion like you might find on a leather chair, such as the famous Van de Rohe Barcelona chair, though the technique can be adapted for more extreme, deeper quilted upholstery such as on a chesterfield sofa. Save some money on buying in architectural models and learn how to do it yourself, it's not too hard once you understand a bit about subdivision surfaces.
Step 1 : Plane
Start with a mesh plane with three by three divisions. You can begin with more if you like but this is a good basic starting point and will give you nine padded sections. As you'll see in the next step you can actually begin with a six by six grid, but the three by three is helpful so you can see which polygon areas will be the 'pads' of the quit and which vertex will be where the buttons go.
Step 2 : Subdiv
Next Subdivide the mesh in order to divide each of the nine pad polygons in to four sub-polygons. What we're after here is to provide an extra vertex in the middle of each of the four edges of a pad to enable us to pull that upwards later to create the right padded shape. As I said in step one this is really just to help visualize the pad sections to make the tutorial easier to follow, you could of course just start with a six by six mesh to begin with. I've highlighted some groups of polygons just to make the pad areas clear.
Step 3 : Down
The polygon mesh is converted to a subdivision surface, use the method appropriate for your 3D app. The four points at the inner corners of the pads are selected and moved down vertically. This forms the depressions where the buttons will go.
Step 4 : Up
Next the nine vertices at the centers of each 'pad' (not forgetting the very center one) are selected and moved upwards. This forms the bulge in the center of each pad. It's looking good but lacks definition at the boundaries of each pad.
Step 5 : Edges
To fix this we need to add in some extra geometry along the four edge loops that divide up the pad sections. In Edge mode select these edges like so. I've turned off the subdivision smoothing so you can see the loops more clearly.
Step 6 : Bevel
These edges are beveled to create the extra geometry needed to sharpen the pad boundaries. Only a small offset is used. The same effect can be achieved by knifing in the geometry, though you'll need to adjust the position of the edges to even up the result. That's basically it. To make a bigger cushion just start with more subdivisions of your plane.
Step 7 : Depth
If you want to create depth to your chair cushion/seat begin by selecting the boundary loop of edges and extruding outwards a little to add a small strip of polygons. This will help keep the outer edge of the cushion from rounding off too much.
Step 8 : Extrude
With the selection still active extrude a second time but with little or no offset. Use your move tool to move the new edges down to makes the sides of the cushion.
Step 9 : Scale
To make the bottom of the cushion (assuming it will not be seen in the final model) extrude the edge once more but this time switch to the scale tool and scale the new edge loop inwards slightly. Repeat the process scaling more to form the underside. You can leave the hole if you want, or close it.
Step 10 : Problem
For the final touch you'll want to add some piping. Here's one way. Select the narrow strips of polygons that bound the pads and chip them off as a new object. When this object is made an SDS though there's a problem. The SDS smoothing causes a 'webbing' effect at the junctions that we don't want.
Step 11 : Fix
There are a few ways to fix this, but the easiest is to select all the polygons except for the two perimeter loops and disconnect them (with preserve groups/keep faces together enabled).
Step 12 : Fix
The next step is to knife in extra edges at the tips of the beading strips that meet the perimeter loops. Finally you'll need to move the end polygons outward to overlap the perimeter beading so that there's no gap.
Step 13 : Extrude 2
Select all the polygons of the chipped off object and extrude them to create the beading, making sure the extrude operation leaves behind the faces you extruded from so that you end up with a closed form.
Step 14 : Final
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SDS Modelling by Simon Danaher ©2006