Maya Lesson 2.3: Combining Objects and Filling Holes

01
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The Bridge Tool

Maya's Bridge Tool
Use the Bridge Tool to close gaps between objects.

Bridge is a convenient way of joining two pieces of geometry and is used quite frequently in contour modeling to fill gaps between edge rings. We'll start with a very simple example.

Place two new cubes in your scene (delete everything else to get rid of the clutter, if you'd like) and translate one of them along the x or z axis to put some space between the two cubes.

The bridge function cannot be used on two separate objects, so in order to use the tool, we'll need to merge the two cubes so that Maya recognizes them as a single item.

Select the two cubes and go to MeshCombine.

Now when you click one cube, both will be highlighted as a single object.

The bridge operation can be used to join two or more edges or faces. For this simple example, select the cubes' inner faces (the ones that are facing one another).

Go to MeshBridge.

The result should look more or less like the image above. My own bridge tool is set so that a single subdivision is automatically placed in the gap, but I believe the default value is actually 5 subdivisions. This can be changed in the tool's options box, or in the construction history under the inputs tab.

02
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Mesh → Fill Hole

Mesh > Fill Hole
Use the Mesh → Fill Hole function to close gaps in a mesh.

In the course of the modeling process, there will likely be many instances where you'll need to fill holes that have developed in your mesh. Although there are multiple ways to achieve this, the fill hole command is a one click solution.

Select any face on the geometry in your scene and delete it.

To fill the hole, go into edge selection mode and double click on one of the border edges to select the entire rim.

With the edges selected, go up to MeshFill Hole and a new face should appear in the gap.

Simple as that.

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Filling Complex Holes

Filling Complex Holes - Cylinder Endcap
Cylinder endcaps are an instance where it's often necessary to modify the topology for better subdivision.

It's pretty rare that a hole will be as simple as a basic four-sided gap. In most cases, the situation will entail a bit more complexity.

Clear your scene and create a new cylinder primitive with the default settings. Look at the cylinder's upper faces (or endcap), and you'll notice that all the faces are triangulated to a central vertex.

Triangular faces (especially on cylinder endcaps) have a tendency to cause unsightly pinching when a mesh is smoothed, subdivided, or taken into a third party sculpting application like Zbrush.

Fixing cylinder endcaps requires us to re-route the topology so that the geometry subdivides more favorably.

Go into face mode and delete all the upper faces on your cylinder. You should be left with a gaping hole where the endcap used to be.

To fill the hole, double click to select all twelve border edges and use the MeshFill Hole command just like we did before.

Problem solved, right?

Not exactly. Triangular faces are undesirable—we try to avoid them as much as possible, but at the end of the day if we're left with one or two it's not the end of the world. However, faces with more than four edges (n-gons they're commonly called) should be avoided like the plague, and unfortunately our cylinder now has a 12-sided n-gon.

Let's see what we can do to take care of it.

04
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Split Polygon Tool

Split Polygon Tool
Use the Split Polygon Tool to divide an "n-gon" into smaller faces.

To remedy the situation, we'll use the split polygon tool to properly subdivide our 12-sided face into nice even quads.

With the cylinder in object mode, go to Edit MeshSplit Polygon Tool.

Our goal is to break down the 12-sided face into four-sided quads by creating new edges between existing vertices. To create a new edge, click on a border edge and (still holding down the left mouse button) drag the mouse toward the starting vertex. The cursor should lock onto the vert.

Perform the same action on the vertex directly across from the first and a new edge will appear, dividing the face into two halves.

To finalize the edge, hit Enter on the keyboard. Your cylinder should now look like the image above.

Note: An edge is never finalized until you strike the enter key. If you'd clicked on a third (or fourth, fifth, sixth, etc.) vertex without first clicking enter, the result would have been a series of edges connecting the entire sequence of vertices. In this example, we want to add the edges one-by-one.

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Split Polygon Tool (Continued)

Split Polygon Tool (Continued)
Use the Split Polygon Tool to continue dividing the endcap. New edges are highlighted in orange.

Use the split polygon tool to continue dividing the cylinder's end-cap, following the two-step sequence shown above.

First, place an edge perpendicular to the one you created in the previous step. You don't need to click the central edge, only the beginning and end points. A vertex will automatically be created at the central intersection.

Now, if we continued connecting vertices diagonally, the resulting geometry would be exactly the same as our original end-cap, which would ultimately defeat the purpose of rebuilding the topology.

Instead, we'll place a pair of parallel edges, like the ones shown in step two. Remember to press enter after you place each edge.

At this point, our end-cap is “quadded out”. Congratulations—you've performed your first (relatively) large-scale topology modification, and learned a little bit about how to handle cylinders properly! Remember, if you were planning to use this model in a project, you'd probably want to quad out the other endcap as well.