Design Nomenclature / Form & Geometry
Silhouette
Also called outline, occluding contour, shape read
The outline a form presents from a given viewpoint — the boundary between surfaces facing the viewer and those facing away. It is view-dependent: the silhouette runs where the surface normal is perpendicular to the eye vector, and on a curved surface it is fixed to no edge in the mesh at all, which is why it slides as the camera moves.
In practice
'Reads in silhouette' is the first test of a form and the one games budget for — everything else can be a texture. Black out the render before arguing about surfacing.
Not to be confused with
- ProfileThe shape of a form's cross-section along its defining direction, or the curve that generates it — the section a sweep drags, the shape a moulding cutter is ground to. A profile is authored: it is an input to the form, which is what separates it from a section, taken out of a form that already exists.
- ContourA curve of constant height on a surface, read against a fixed direction — the level lines of a topographic map, the ribs of a stacked laser-cut model, the layers a slicer emits. A family of them describes the whole surface, and where they crowd, it is steep. Also used loosely for any line drawn following a form.