Objects Easy to Unwrap in Maya Can Unwrap in Maya

Unwrapping UV in Maya is a process of laying out the polygon object's UV components into its 2D space counterpart as preparation for the texturing process.

To begin the process of unwrapping, do ANY of the following steps:

Go to 'Modeling' menu set by pressing 'F2' or pulldown menu.
Setup your Workspace to UV Editing by going to the screen's top left corner as shown.

Regardless of what kind of model you're working on, UV unwrapping workflow in Maya generally involves a 4-step process:

Projecting
Cutting and Sewing Edges
Unfolding
Layout

1. Projecting

Projecting is the first step in UV unwrapping. It's a process of applying initial UV projection on a polygon model. Ideally, it should start with clearing the existing UVs which Maya created by default.

This can be done by selecting the polygon model first then go to UV>Delete UVs to clear out existing UVs or go to the UV Editor window and go to Edit>Delete.

On a side note, deleting UVs is totally optional and can be skipped. This is because same effect happens when we directly apply projections onto the model which would be the next step.

Any projection will work fine for this first step. For this example, I find Camera-based projection to be the most practical and easiest to deal with.

In most cases, Camera-based projection will do most of the job in different projects and scenarios

To project using Camera-based:

Select the polygon model
While the model is selected, do any of the following:
- 'Modeling' menu set: UV>Camera-based
- In UV Editor: Create>Camera-based
- UV toolkit: Create>Camera-based

The first step has been covered. This model is now ready for the next step: Cutting and Sewing Edges. .

2. Cutting and Sewing Edges

This stage requires carefully deciding where to strategically place the cuts in the UV. The cuts represent where the seams will be. The general rule for this stage is to place the cuts in areas of the model where you want the seams to be less visible or less obvious. That way, it minimizes if not eliminate the chances of seams getting seen.

For enhanced visual feedback, It is highly recommended to first enable shaded view and display Texture borders at this stage of the process.

There are different ways and tools to intuitively cut and sew UV edges but all achieve the same result.

One of the newest tools, the 3D Cut and Sew UV Tool allows you to cut and sew UV edges but will only work in 3D view.

With the polygon object that just previously got the Camera-based projection applied to, the next step is to cut and sew its UV edges using 3D Cut and Sew Tool.

How to use 3D Cut and Sew UV Tool

First, access this tool by going to Modeling menu: UV>3D Cut and Sew UV Tool.
Using this tool, click the polygon model.
Use the tool to define where the seams will be by click+dragging on the edges
Holding ctrl while click+dragging will sew back the seams.
After defining the areas where the seams will be, the model is now ready to be unfolded.

Using the 3D Cut And Sew UV tool to cut the UV edges

Check out the video down below to see this tool in action which starts at 1:03

3. Unfolding

This step is relatively easy and simple. By this time, your polygon model already has its UV edge cuts in-place in strategic locations. Here's how to unfold:

Select the polygon model.
In the UV Editor menu window, go to Modify>Unfold or (Ctrl+U). You can also access the same tool in the UV Toolkit under Unfold category.

That completes the unfolding step. Alternatively, you can use Unfold Tool for this process. It's an interactive tool that lets you unfold the UVs by painting over it. It can be found via UV Toolkit under Unfold category or, by right-clicking in the UV Editor window to display the marking menu and selecting Tools>Unfold Tool

4. Layout

Now that the UVs on your polygon model has been unfolded, we get to the last step of UV unwrapping: Layout. Laying UVs out is the process of neatly arranging UV shells or UV islands within a zero to one UV space.

Use the Layout button to automatically arrange the UV shells or islands. Shift+clicking on the Layout button opens up additional options.

Selecting UVs and other components

UV toolkit has a selection mask feature that allows you to easily mask-select a specific set of components. Along with what components to select, just right beneath are radio buttons on those components are selected. (Pick, Drag, Tweak)

Selection Mask: Converts selection to Vertices, Edges, Faces, UVs and UV shells

Alternatively, use the marking menu to select components by right-clicking on the UV Editor while the object is selected. Ctrl+clicking on the UV Editor while the object is selected displays the marking menu that converts the currently selected components to a different set of components

Arranging UVs

Use move, scale and rotate the same way you would in 3D when arranging and laying out of UVs in the UV Editor. In addition to that, there's a section in the UV Toolkit that contains tools that will speed up and make this process a lot faster and easier.

For a more in-depth exploration of UV in Maya, also check out Brent LeBlanc's in depth tutorial.

Other Ways to Cut and Sew UV edges in Maya:

Within the UV Toolkit and under the Cut and Sew Category, you can find other alternate tools to accomplish the same thing the 3D Cut and Sew UV Tool does. Again, make sure Workspace is set to UV Editing.

Cut and Sew UV Toolkit — UV Toolkit, Cut And Sew Category

How to use Cut/Cut UV Edges

Select a polygon object.
Access that polygon's edge component by right-clicking on that polygon object and choosing 'Edge' (Can be done both in perspective view or UV Editor).
Select the edges to cut.
While the edges are selected, use the Cut command by either going to UV Toolkit, Cut and Sew >Cut or from marking menu by Shift+Right clicking and choosing Cut

How to use Cut Tool

Select a polygon object.
In the UV Editor window, activate the Cut Tool by either going to UV Toolkit and accessing the Cut and Sew>Cut Tool. Alternatively, via marking menu by right-clicking on the polygon object and choosing Tools>Cut
Now that the polygon object selected and Cut Tool activated, use the tool to directly cut the edges like you normally would when using a real-world knife.

How to use Create UV Shell

Select a polygon object.
Access that polygon's face component by right-clicking on that polygon object and choosing 'Face' (Can be done both in perspective view or UV Editor).
Select the faces you want to create a UV-shell out of.
With those faces selected, right-click on it to expose the marking-menu in the UV Editor and choose, Cut and Sew>Create UV Shell. Alternatively, go to UV Toolkit under the Cut and Sew category.

Other Ways to Sew UV edges in Maya:

Move and Sew

Select a polygon object.
Access that polygon object's edge component by right-clicking on that polygon object and choosing 'Edge' from the marking menu (Can be done both in perspective view or UV Editor).
Select a set of open edges. This step will highlight the other set of open edges where it will get connected.
While the object is selected in the UV Editor window, Shift+Right click on it to expose the marking menu and choose Move and sew.

Sew Tool

With a selected polygon, bring the UV shell close to another UV shell that shares connecting open edges with.
Make sure the connecting open edges are facing each other.
Right-click anywhere on the UV Editor to expose the marking menu.
Within the marking menu go to Tools>Sew
With the Sew tool active, hover over those connecting edges to sew them. (bigger brush size gets wider influence)

Stitch Together

This tool works very similar to Move and Sew by bringing a UV shell right next to another and stitching their common edges together

Select a UV edge or set of edges of any shell.
Right+Click on the UV Editor to expose the marking menu.
Go to Cut/Sew>Stitch Together

This concludes the Maya UV unwrapping and layout. Check out Modeling Tools in Maya

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Source: https://create3dart.com/how-to-unwrap-uv-in-maya-2018-2019/