basics: subdivision surfaces
In our continuing series of CGI basics, we look at using subdivision surfaces
Explore the benefits of utilising subdivision surfaces
If you’re new to CGI, you may feel that there are far too many tools to choose from in a dizzying array of software. This series aims to break everything in CGI down to the very basics, so that every artist can be armed with the knowledge of which tool is best. This time we take a look at subdivision surfaces.
Creating a realistic CGI model is dependant on a large number of factors, and one of the main components is naturally the polygons themselves and how they are divided and flow to represent the base mesh.
Smooth curves and rounded edges can be difficult to represent using standard modelling techniques, as triangles or quad polygons, by their inherent nature, are not curved.
Subdivision surfaces do the heavy lifting when it comes to representing these refined edges, as they take the vertex information and re-interpolate it via a variety of mathematical techniques to show a smoothed shape.
Using subdivision surfaces makes modelling organic shapes, especially for animation, much simpler than using a purely polygonal model, as less vertices are required. This means simpler control points and therefore a simpler system to set up.
The key to using subdivision surfaces properly is in understanding how a specific 3D application implements its smoothing paradigm. While there are a number of standards for subdivision surfaces, not all applications implement them, which can make switching meshes with subdiv surfaces between applications unpredictable. Edge weighting, where an edge loop can tighten a curve without the addition of any more vertices, is a classic example of a subdiv modelling technique that is implemented differently across applications, if at all.
Understanding how edge loops work and influence topology ensures that the base mesh from which the subdivision surfaces are derived uses as many best-practice polygonal-building techniques as possible. Minimising ngons with flowing edge loops can make using subdivision surfaces a straightforward experience, which benefits both the artist and the finished scene.
Author Mike Griggs Mike Griggs is a 3D and visual effects artist with vast experience across the industry, as both a creator and a technical writer. www.creativebloke.com