Descripción de las nuevas clases u operaciones necesarias

cut like that would allow the shirt to unfold along the shoulder and the top of the arm.

UV Unwrapping and Arranging

Now we are ready to unwrap the model, and we will use the Unwrap UVs using LSCM command to do so. LSCM is a common acronym in the 3D UV world and stands for “Least Squares Conformal Mapping.” Basically, the LSCM algorithm keeps stretching and deforming to a minimum by attempting to preserve the angles of the polygons, while fl attening and relaxing the scale.

The result should look like Figure 3.31 , which puts us well on our way to a clean UV map. There are other unwrapping tools in the UVs/Materials >

Recreate UVs drop-down menu, but for the most part, they are for spot work or setup on a complex model. The main tool is LSCM.

The next step involves mirroring. This might not be necessary all the time, and would likely be unnecessary for a simple object like this shirt. However, it’s always an option if working with a mirrored object, and it’s important to understand how it works.

● Select the object, and then select Mirror UVs from the UVs/Materials drop-down menu.

The shirt should then appear folded on top of itself because we have told Silo these two sides will look the same. However, unlike with the 3D view, symmetry isn’t enabled, and working with two pieces on top of each other can be diffi cult. So, before we move on, we need to:

^● Add a new seam down the front and back middle of the shirt ( Figure 3.32a ).

^● Double click on one of the shell faces (or click on a face and press Shift  1 or select Selection > Expand Selection from the top menu) to select all of the connected faces.

● Slide one of the UV sides out of the way ( Figure 3.32 ).

We’ll essentially discard one of the sides, focus on getting the other just right, and re-mirror later.

Now it’s time for resizing and moving the UV map to get it centered in the UV square. All the tools and manipulators available in the standard modeling kit are available to move the UV map around, but there are also some nice custom tools in the UVs/Materials drop-down menu.

● Try either Arrange UVs in Bounds or Scale UVs to Bounds after selecting the whole mesh and you should get something that looks like Figure 3.33 . FIG. 3.31 LSCM unwrapping of the shirt. FIG. 3.32 You can split the mirrored sides of a

UV map to ease the map manipulation work.

Unwrap UVs using LSCM;

UVs/Materials  Unwrap UVs using LSCM  U;

These commands, along with Scale UVs Proportionally are incredibly valuable when a UV is in multiple unmirrored pieces, as we will see in Chapter 13.

UV Manipulation

Now comes the manual manipulation of the UV map into a nice and tidy form. This will help the shirt display in as natural a state as possible, and there are some important tools to help in the process. Pin UV Vertices , accessible from the UVs/Materials drop-down menu, will fi x points on the UV grid to a particular visual point on the image. This can be helpful in lining up geometry with a texture image and for smoothing out the UV interior.

This will have a smoothing eff ect on the internal UV geometry while the edge stays locked, helping the 2D image fi t better on the 3D model, (see Figure 3.34).

Another very important tool that we won’t use here, but will show in Chapter 13, is the Live UV Unwrapping tool. Often with UV maps, parts of the mesh will be tightly compacted and distorted even after LSCM unwrapping. Moving these sections around vertex by vertex can be painstaking, so the Live UV Unwrapping toggle ( UVs/Materials > Unwrap UVs using LSCM or Control  Alt  U ) will allow you instead to pin certain sections that you’d like to stay put, and then, by dragging a vertex or two, spread out the rest using the LSCM algorithm in real time. Because our T-shirt mesh is well spaced to begin with, the tool isn’t necessary, but feel free to try it anyway to see the impact. We’ll use the tool in Chapter 13 to create the UV map for our character’s jacket.

FIG. 3.33 The LSCM mesh can easy be re-centered and resized with either the Arrange UV in Bounds or the Scale UVs to Bounds command.

Pin UV Vertices; UVs/

Materials  Pin UV Vertices  Shift  U;

At this point, our work is mostly done and we’re ready for cleanup. We need to mirror our changes on to the second side, fl ip one side, and then merge the two sides together. To do this:

^● First, select the side we’ve been working on and select UVs/Materials >

Mirror UVs . This will move the side we’d placed on the bottom back on top of what we’ve been working on and mirror the UVs.

● With a single side selected, select UVs/Materials > Flip UVs , another specialty UV tool, to horizontally fl ip one side so you’ll be able to slide it over and get something that looks more like what we started with ( Figure 3.35a ).

^● Finally, we need to merge the two pieces back into one. This can be accomplished by selecting the seams on the 3D object and clicking UVs/

Materials > Unmark UV Seams . There is also a specialized UV command for merging, UVs/Materials > Move and Sew , that will move the polygons with the merge in an attempt to minimize UV distortion. In the case of the T-shirt, since we already have the square shape we want, our best bet is to simply unmark the seams.

The fi nal product should look something like Figure 3.35b .

To take the texture map into another program, you can export what’s in the UV square as an image by using UVs/Materials > Export UVs to Image . The resulting work in the third-party program can then be imported as a texture and applied to your model.

Conclusion

That covers the main tools and workfl ows for Silo. We hope this section prepares you to take on the project covered in the next several chapters, and can serve as a reference when working with Silo. Now, on to our main model!

FIG. 3.34 The standard polygon tools can help straighten out UV edges, which can then be pinned and the interior polygons can be smoothed using LSCM unwrapping.

FIG. 3.35 The fi nal step involves eliminating the seam needed for mirroring.

Character Pre-production

Over the past few chapters, we introduced you to the world of subdivision surfaces along with a variety of ways to create your models. You should also have a basic understanding of the application we will be using as we move forward in this tutorial.

In this chapter we start to look at the character we will be creating and make sure we are fully prepared before we start to build her.