How To Smooth An Object When Using The Subdivide Tool?

Most tools in Blender will have a tool variation and then a modifier that acts as the tool but can be used procedurally. This is true for the subdivide tool which has a procedural version in the form of the subdivision surface modifier. A key difference between the tool in the modifier is the seeming ability for the subdivision surface modifier to not only increase our geometry but to smooth it out at the same time.

To enable these smoothing effects on the subdivide tool, you will want to open up the operator panel after you have used the subdivide tool on your model. One of the first options in the operator panel will be the amount of smoothing applied to your object. This will be set to zero by default. Increase it to add smoothing.

Even though most tools have modifier variations, there are always going to be subtle differences between the main tool and its modifier variant, and it’s important to understand the differences between them and when to use each one.

The Difference Between Subdivide And Subdivision Surface When First Used For Smoothing Edges

Devil a few key differences when using the subdivide tool compared to the subdivision surface modifier. The most obvious of which is going to be the lack of smoothing with the subdivide tool.

When using the subdivision surface modifier, smoothing is applied to our model as a default. However, when we are using these subdivide tool, this is not the case and we are only just adding to our objects geometry rather than smoothing it.

Another difference between the tool and the modifier is the way that the extra geometry is calculated. Two different formulas are used for the tool and the modifier. When it comes to these, subdivided told the formula that is used is the following.

(N + 1)2 = Number Of Faces

To make sense of this formula, take a single face and subdivide it. You will notice that it becomes four faces. In the formula, N represents the number of cards found in the operator panel. The number of faces requires you to plus one to the number of cuts, which in this case equals 2. Then you take that total and you multiply it by itself, which gives us the value of four.

Increase the number of cuts to 3 and the equation looks like this…

(3 =1)2 = 16

The calculation that is used for the subdivision surface modifier is a bit different. If we use the modifier on a cube object then a value of 1 creates the same number of faces as the subdivide tool, but if you increase the viewport levels value, which is like the subdivide tool’s number of cuts, it jumps to 16.

For every level that we increase the modifier by, it takes each face of the previous level and divides it into 4.

4n = Number Of Faces

In the formula for the modifier, you use the value of 4 and square it be the level value (N) to get our total number of faces that replace the original.

But do these formulas have any real impact on the way our object is smoothed? The answer is yes, as with the subdivision surface modifier the original topology is better maintained. This means that if you try to use both tools to create a sphere from a cube, then the modifier will yield a slightly better result.

How To Smooth The Geometry When Using The Regular Subdivide Tool?

When using the traditional subdivide tool, we can divide up our geometry into a series of smaller faces without deforming our objects through smoothing. But what if deforming the objects using a smoothing technique was exactly the thing we were looking for?

Smoothing is an attribute that is a part of both the subdivide tool and Subdivision Surface modifier. It’s just that with the modifier, smoothing is enabled by default. When it comes to the subdivide tool, we need to enable smoothing in the operator panel.

First, use the subdivide tool on your selected object and the operator panel will appear in the bottom corner of the 3D viewport. Open up the operator panel and you will see a series of properties that you can change for the subdivide tool.

The second of these is the smoothing property, which by default has a value set to 0. You can increase this up to a full value of 1 to enable smoothing on your object’s vertices. The closer to one, the more your object will smooth with the subdivide tool.

Smoothness Value Operator Panel

Because of the different formulas used for the subdivide tool compared to the modifier, the way smoothing is applied is going to be slightly different. Take a look at these two versions of Suzanne the monkey. One of them has been subdivided and then smoothed and the other has been subdivided with the modifier.

As you can see, the result of the modifier is better than that of the subdivide tool, so this should be taken into consideration depending on exactly how you want to smooth your objects.

Keep in mind though that with the subdivision surface modifier it’s either yes or no. You either have smoothing or you do not, but with the subdivide tool you actually have more control over this property.

How Not To Smooth Your Geometry When Using Subdivision Surface?

So we now know that to enable smoothing for the subdivide tool we need to change the smoothing value in the operator panel. But what about the subdivision surface modifier? Let’s take a look at the structure of the modifier in the modifiers tab.

Subdivision Tab

While we have the option to increase and decrease the number of subdivisions for our modifier, we do not seem to have the option to turn off the smoothing effect. But actually, we do have this option right at the top of the tab. Here you have two options, either Catmull-Clark, or simple.

These aren’t the two main methods of subdivision that are used by the modifier. Catmull Clark is the default and is also the one that calculates the smoothing effect that the modifier generates on your model’s surface.

Subdivision Simple Method

The simple option on the other hand only adds your geometry and does not smooth it in any way at all. This means that by using the simple option, we can add our geometry without needing to make any changes to its shape.

Can You Unsubdivide Your Model And How Does This Effect The Smoothness Of The Geometry

The ability to subdivide your geometry is very simple and you can do so with both the subdivide tool and the subdivision surface modifier. But what if you wanted to reverse this and unsubdivided your model?

The way this works is a little bit more complex as it’s more difficult for Blender to accurately reduce geometry compared to increasing it while maintaining good topology. However, like subdivisions, there are two methods of un-subdividing, both with a tool as well as a modifier.

The first method is to use the unsubdivided tool, which is going to be located in the Edge menu that you will find in the header bar of the 3D viewports while in edit mode.

Un-subdivide Location

With this tool, Blender will attempt to reduce the total amount of geometry on your object by using the flow of geometry or your topology as the baseline.

It has to be said that Blender out does not always make a very good job of this, and if you are going to use the unsubdivided tool to reduce your geometry then you will need to double cheque your model after using the tool to clean certain areas up.

In the example below we have two images. One of our images is of a plane when it has been subdivided and then the second where it has then been unsubdivided to reduce the amount of geometry. You can see the amount of geometry is reduced, but it also creates a different pattern towards the sides of the plane.

The Modifier Alternative

Just as we can use the subdivision surface modifier instead of the subdivide tool, we can also use a modifier in place of the unsubdivided tool.

The modifier that is best suited to this task is the decimate modifier, which allows us to procedurally reduce the total amount of geometry on our objects.

The Three Methods Of Decimation

When using the decimate modifier, we can choose one of three methods. Collapse allows us to merge edges together. Un-subdivide allows us to effectively reverse our subdivision, similar to the un-subdivide tool, using the iteration value. And the planer method will allow us to reduce the amount of topology on our model based on the angles of our edges.

As you will probably have guessed, the unsubdivided method is the one most similar to the unsubdivided tool and works pretty much the same way.

How Does This Effect Smoothing?

Regardless of which method you choose to reduce the topology of your model. You will inevitably affect the smoothing of your objects.

After all, the amount of geometry on your model can be used to determine exactly how smooth it is capable of being around its edges.

The one potential exception here is the planer method of the decimate modifier, which reduces your topology based on the angular limits.

With the planar option, we reduce the amount of geometry where our faces are flatter and so long as we keep the angle limit fairly low, it will not affect the more curved areas of the model which have higher angle limits.

Using The Smoothing Tool To Relax And Smooth Your Edges Without Needing A Subdivision

You don’t need to use the subdivide tool or the Subdivision surface modifier to enable smoothing on your model. There is such a thing as a smoothing tool that you can use in Blender to relax your vertices.

In fact, this tool can be used in combination with something like a subdivision surface modifier to make your objects smoother and more spherical.

The smoothing tool can be located on the tool shelf. It will look like a purple ball, so you can select this smoothing option and it will enable the tool in the 3D viewport which will appear as a yellow handle. Click and drag on this handle and you will apply smoothing to your selected vertices.

Smoothing A Subdivided Cube

Combining The Bevel Tool With The Subdivide Tool For Better Smoothing

When using the subdivide tool all by itself on a model and then apply the smoothing effect, you may notice that the smoothing doesn’t look quite right, especially if you have applied smooth shading. You may also feel like you want to apply the smoothing effect to the model, but you still want to maintain the general shape.

What we can do here is we can combine the subdivide tool with the bevel tool. For the example with a simple cube, we can use the bevel tool to create curved edges around the sharp areas of our cube.

Use Bevel To Create Smooth Edges

We don’t need many segments for the bevel because we’re going to be adding those segments with the sub to fight all. So keep the number of segments to a minimum.

After using the bevel tool, we can then use these subdivide tools to add our additional segments and more geometry overall for our cube. Then we can increase the smoothing value to improve the look of our objects. Or we could use the subsurf modifier, which is even better here.

Subdivide And Smooth Cube

Thanks For Reading The Article

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