Modelling an alien

( page 6)

Six: Instancing the geometry

Again we'll save the scene then delete the History and resave with a different name. All the head surfaces are selected and then the Edit>Group command is used to create a single group that can be selected easily.

In the Duplicate options box the geometry type is changed to Instance. Now when the head is duplicated the copy is simply a reference and not a discrete object. To make the duplicate group a mirror image, its X scale was set to -1.

Because of instancing, whatever changes we make to the original objects within the head group are reflected (literally) on the opposite side. In this way symmetry is maintained, and with this in mind we decided to modify the back of the head. However, in order to get a smooth join and close the gap we would have to use the Align Surfaces command, which only works between two discrete objects.

We must back up a few steps and delete the instanced group. This time everything except the head surface and the extruded band are grouped, then instanced to the other side as above. The remaining objects can then be duplicated as real geometry. The two head surfaces are selected, then the Attach Surfaces command is selected. This joins two objects along an edge and creates a single surface.

To fill in the hole at the back we need to add some extra rows of CVs. Right-clicking on the surface pops up a marking menu allowing you to select different components (CVs, Hull, Isoparms etc). A single Isoparm is selected and the Insert Isoparm command used to add the extra row of points.

Now we can select Hulls in turn and fill in the hole by scaling them down. The last Hull has been scaled to zero in y and z so that all the points lie on a line. It has caused some stretching but at least it's at the back. To draw attention away, a hole was created by trimming the surface and lofting between curves and the trim edge..