Subdivision Modeling Tutorial

Advanced

By: Simon B. ($imon)

In this tutorial I will be explaining some basics of optimising your models for subdivision modeling, increasing the quality of high poly work a lot! 

The tutorial was made in 3d Studio Max, but can be applied in any 3d modeling application.

As the name might imply, subdivision modeling is the method of modeling something and subdividing it afterwards. Here an example of subdivision modeling and the differences between a regular model, one that is subdivided, and a model optimised for subdivision. 

1. Unsubdivided regular model
2. Subdivided regular model
3. Subdivided model that was optimised for subdivision 

(hover over the images for a wireframe) 

So how do we optimise a model for subdivision?

First off, the bevel tool. Beveling is your big friend when it comes to high poly modeling, since you define how sharp an edge is by beveling it more or less.

Here is a basic cube with different amounts of bevelling:

But just hitting the bevel button on every edge we want to have sharpened is not enough. Some areas will get distorted and will not look good subdivided. Here are a few things you will have to do manually after beveling.

1. Points with five lines attached.

If a point you are bevelling has more than four lines attached to it, a bevel will very likely mess up your model. As you can see in the following image, this creates a triangle between the two lines of the bevel. These triangles have to be removed by merging the two points as shown in the image. Key rule is to have the two lines of the bevel completely parallel, so no extra points etc.

2. Distance from bevel to the next line.

When subdividing, a 3d program takes into calculation how far the lines are apart, so not only the lines we just beveled, but also the ones that come after that. In the following image you can clearly see that the edges are not evenly sharp, even though they all have a bevel of 0,01.

To solve this problem you can add helping lines (second image) to be taken into account with the subdivision, and it will make the edge sharper (last image)

This also counts for larger surfaces.

Something I very often do is extruding a cylinder, but with doing this, the endings of the cylinder are usually multi-sided polies, which do not show up well after subdividing.

This is why at the end of the cylinder I inset an extra line to have it smooth well (see the image)

3. Corners

It probably is clear that for beveling a corner, you have to select the three edges of the corner and bevel these simultaniously. But what if the corner is a bit more complex? Like the image below. Beveling just the three edges would suffice, but the subdivided result will not look too great, therefore the solution in this case is to bevel all four edges.

There are lots of other complex corners you might have to deal with, and you will have to experiment how to get the best result.

A few more tips:

- To select the edges to bevel, some selection tools come in handy like ‘select loop’.

- Wait with beveling until your whole model is done, then select all edges you want to bevel and do them at once, so lines will not interfere with each other. 

- Instead of beveling you can also use the Cut tool to make sharp edges, which in some cases can be easier, and will not produce any errors that need fixing afterwards.

There are a lot more tips and tricks on how to have your model smooth correctly, but the best way to learn is to merge, add, remove points yourself and see how it looks the best once smoothed. 

I hope this tutorial was at least a bit helpful, and will help you make higher quality models. 

Good luck!