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Subdivision sketch: studying shapes and simplifying subdivision.

This write-up is a brief overview of a simple, shape based approach to subdivision modeling. This approach, with the primary focus being to create accurate shapes that define the loop flow paths, can help streamline the modeling process for most hard surface objects.

Working without enough information to visually interpret the shapes tends to add unnecessary frustration. So, start the modeling process by researching and gathering different references. Which can include things like background information, images, measurements, videos, etc. These references should be used as a guide for modeling real world objects and as a baseline for evaluating the form and function of design concepts.

Look at the references and think about how the object is made and how it's used. This will provide additional context that ties the real world details from the reference images to the creative narrative used to guide the development the artwork. Something that also helps inform decision making during the modeling process and provides inspiration for developing the visual storytelling elements that carry through to the texturing process.

Analyze the shapes in the concepts and references. Identify the key surface features and observe how they interact with each other. Establish the overall scale of the object then figure out the proportions between the different shapes that make up the surfaces. Use this information to come up with an order of operations for blocking out the basic shapes. If necessary: draw out the basic primitives that make up the object. Highlight flat areas, curved areas and the transitions between them.

Most topology flow issues can be solved during the block out. Which is why it's generally considered best practice to: Use the edges of the existing geometry as support for shape intersections whenever possible. Use the minimum amount of geometry required to create reasonably accurate shapes. Use a segment matching strategy to maintain uniform edge spacing when joining curved shapes.

Develop the block out in stages. Keep things relatively simple for the first few iterations of the block out. Larger shapes should generally be defined first, while also keeping the smaller details in mind. Focus on creating shapes that are accurate to the references then solve the major topology flow issues before adding the support loops. Overall mesh complexity can also be reduced by modeling individual components of the object separately.

Let the shapes define the loop flow. Some features may have curvature that influences or restricts the loop flow of adjacent surfaces. Block out those shapes first then adjust the number of segments in the adjacent surfaces to roughly match the edges where the two shapes intersect. Any significant difference between the edges of intersecting shapes can usually be averaged out between the support loops.

With this iterative approach to blocking out the shapes then solving the topology flow issues, the edges that define the borders of the shapes become the loop paths. Which means most of the support loops can be added by simply selecting those defining edges and using a bevel / chamfer operation to add the outside loops. Alternately, loop cuts and inset operations can also be used when the support loops are only needed on one side of the edges that define the shapes.

This shape based loop routing strategy tends to require little manual cleanup and can be mostly automated using modifiers. Something that helps make hard surface subdivision modeling much more approachable. The examples in this write-up show how this basic workflow can be applied to a moderately complex, plastic injection molded part which has a mix of soft, lofted shape transitions and hard seam lines. Which are commonly found on a variety of different hard surface objects. So, the same sort of approach will generally work with most hard surface modeling workflows.

Recap: Analyze the shapes in the concepts and references. Develop the block out in stages. Let the shapes define the loop flow. Match the segments of intersecting shapes. Use the existing geometry to guide the loop paths. Solve topology issues early on then add the support loops.