Best Of

Everyone has offered really solid advice. Think that Neox, Eric and sacboy have summarized the key points of the issue and provided a lot of good links to additional resources on the topic. Just wanted to quickly address a couple of different points brought up in the discussion.

Subdivision modeling tends to be an iterative process. So, there's reasons to both keep things simple and use more geometry. Blocking out the major forms is a lot easier to do when there's less geometry to manage but adding small details, to surfaces with compound curves, can require using more geometry to provide support around the shape transitions.

Sometimes the block out process can be simplified by combining adjacent panels but arbitrarily modeling an entire car body as a contiguous quad mesh tends to introduce a lot of unnecessary complexity. The panel lines provide a natural break in the shapes. Which can be used to reduce loops in a non-visible area or separate sections of the mesh so the local density can be increased to support small surface details.

The examples below show what this process could look like. Parts of the mesh may be merged or split for different reasons and during different stages of the block out. Most of the time this decision will come down to balancing accuracy and editability.

All of the reflective surfaces and subtle forms make automotive body work a challenge to model. Creating a base mesh with relatively consistent loop spacing is generally considered best practice because it helps prevent artifacts in the edge highlights and surface reflections. There's differing schools of thought on other workflow topics. E.g. rink-wrapping a guide shape, using creases instead of support loops and how much subdivision should be applied before detailing. So, it's probably worth considering what the model will be used for and read up on the current best practices for that particular discipline.

When in doubt, a flow check with different materials and a reflection map can help highlight any problem areas. Here's a link to a detailed write-up on how to do a flow check. https://www.ebalstudios.com/blog/3d-modeling-artifacts-flow-check-reflection-map As mentioned in the article: there are some inherent and unavoidable limitations to the surface quality of polygonal models. While the flow check is generally a good indicator of surface quality, it's also important to focus on the final results and avoid making unfounded assumptions based solely on a model's wire-frame.

Below is a comparison of a base mesh with contiguous panel lines and a base mesh with split panel lines. Each type of material preview shows a different aspect of the subdivided mesh. A material with a wide highlight roll-off is good for catching most types of subdivision artifacts but more reflective materials provide a deeper picture of the surface's overall quality.

A contiguous, low density mesh is fine for blocking out larger shapes but often lacks the amount of geometry required to support complex shape intersections on curved surfaces. These small, poorly supported surface details can interrupt the existing edge spacing and this tends to reduce the overall quality of the surface. Sometimes it is possible to compensate for undesired smoothing deformation by adjusting the shape of the base mesh but this tends to introduce other flow issues that are still visible in surface reflections.

The comparison below shows how the overall surface quality from the block out is preserved by applying one level of subdivision before adding smaller surface details. Increasing the mesh density does reduce the editability of the larger shapes but this isn't an issue since they were finalized in the previous block out.

If the project does require a contiguous mesh then any components that were split off during the block out or detailing processes can be subdivided to match and merged with the adjacent panels. Below is an example that shows how applying the subdivision level for detailing also locks in the existing curvature of the shapes and reduces the overall visibility of flow changes between panels that have been merged.

It's also worth mentioning that there's a few different ways to reduce edge loops without interrupting the flow of the mesh in a visible area. Here's a link to another write-up that looks at several different ways of handling support loops that intersect curved shape transitions. https://polycount.com/discussion/comment/2769713/#Comment_2769713

In addition generally following sentiment, offered by others.

Sometime ago, stumbled across insight that clarified in my own mind an optimal polygonal workflow, creating Class A (Reflective Observable) surfaces that personally remains a simple guiding set of vehicle modeling principles - i.e.

• Prior Planning - respective to an envisioned outcome
• Blockout Shapes - apply accurate dimensions
• Generate a Basemesh - before subdividing, use of a low polycount plus uniformly spaced edgeflow
• Finalise Basemesh - then apply secondary/tertiary details