Dividing a Character

Dividing a Character

The most efficient way to texture a character is to divide it up into areas whose shapes lend themselves to a particular type of projection. For example, an arm could either be treated as a cylinder, or if divided lengthwise, could use two planar projections. The idea is to approach the mapping procedure with a strategy.

Here is what to look for when choosing how to break up the character:

• Look for areas that resemble the projection shape most closely. If you map a cylinder with, say, a planar projection, you will wind up with stretching on two sides and overlap on the back; overlap is bad in almost all cases.

• Look for areas that can share the same texture and projection information. The left and right side hand areas, and maybe even the pants legs or the face (if symmetrical) are likely candidates.

• When choosing where to cut, try to hide seams wherever possible. Look first for natural seams like waistbands and collars. If there is no natural seam, choose the next least conspicuous spot, such as under the armpit, between legs, under hair, and so forth.

Splitting the geometry up will make it easier to apply the initial UV projections to the character. With these in place, we can then go in and tweak the UVs individually to reduce any undesirable stretching and overlap.

We will now begin working on Kila to show how best to divide her. No mapping will be applied at this stage.

Kila

NOTE

It's been a while since we looked at the Kila model because we have been working on Grae. Take this opportunity to have a fresh look at the model, making sure you are happy with it. When you're ready, we will begin by examining the torso and arms.

Torso and Arm Preparation

Kila currently only has one-half of her upper body; the entire right side is a mirrored instance. We're going to delete the instance and create a mirrored copy of the left torso for her right sidebut first we will extract her arm. We do this because although we want to map then entire torso, the mapping for her left and right arms can initially be the same, so we only need one arm to exist at this time.

1.

Select the faces that make up Kila's left arm and extract them, separating the arm from the torso (Figure 8.6).

Figure 8.6. Extract the left arm.

2.

Now we can go in and finish preparing the torso. First delete the mirrored instance, so only the left half of her torso remains.

3.

Use the Polygons > Polygon Mirror tool, making sure Weld Vertices is enabled. This will create the right side.

4.

If the vertices running down the center of her torso did not all lie on the same plane when you did the mirroring step, you may need to go in now and make sure that they are welded correctly. When that's done, smooth the edges.

We now have a complete torso that is almost ready for mapping. There are two ways to approach this area:

• It's basically cylindrical in shape, so we could map it cylindrically. This would produce a good result, but it can be difficult to control the positions of the seams. (The seams are the areas where the cylinder edges meet. If you imagine rolling a piece of paper around your arm, this is the cylindrical projection. The position of the seams will be the places where the edges of the paper meet.)

• We could detach the front and back, planar-mapping both. This would give a better UV layout. We'd only have to adjust the sides and the breast area because they will initially overlap and be stretched.

Another advantage to splitting the torso would be the placement of the UV seams. They would run down Kila's sides, so we could disguise them as the seams on her T-shirt. In addition, they would also be hidden when her arms are down, which would be for the majority of the time.

Planar mapping seem to be the best option, so let's now split the torso in two.

1.

Select the faces that make up Kila's front, selecting the ones that face forward more than backward. Use Extract to separate them (Figure 8.7).

Figure 8.7. Split the torso into the front piece and the back piece.

The front and back are now separated and prepped, ready to be mapped.

We will apply cylindrical mapping on the arm, because the shape is almost cylindrical and it will give us an opportunity to see this form of projection demonstrated. Alternatively, you could apply the same technique that we used for the torso, as we will with the legs later. The hand, however, will need planar mapping to both the top and bottom, so that we can apply a different texture to each side.

2.

Start by detaching her hand from the arm. Select the faces that make up the hand and Extract them (Figure 8.8).

Figure 8.8. Extract the hand.

3.

Finally, separate the top of the hand from the bottom (Figure 8.9).

Figure 8.9. Separate the top of the hand from the bottom.

The torso, arm, and hand are now ready to be mapped. Let's continue down her body now and work on the legs.

Leg Division

For Kila's legs, we can adopt the same technique we used on the torso. Her jeans will have a seam that runs down the outside and the inner leg; this can be used to disguise the UV seam.

As you did with the torso, select the front faces (Figure 8.10) and Extract them.

Shoe and Belt Division

Continuing on, we get to the shoes. Both shoes will be mapped the same, so we can delete the one on the right for now, and duplicate the left shoe once mapping has been applied.

There are a number of ways you can approach the shoes, depending on the amount of detail you wish them to have.

• A simple planar projection from the side is usually a good way of quickly mapping the shoe. This does mean, though, that the inner and outer sides of the shoe have to be the same.

• You could use automatic mapping, as demonstrated earlier with the hand model, but this might give unpredictable resultsyou could wind up spending most of your time rearranging the UVs.

• To get the most detail into the shoe, the best approach is to manually split up the model. This will also give you more control over the UVs' placement. This is the method demonstrated in this discussion.

Separate the sides, top, front, back, and bottom (Figure 8.11). We will apply planar mapping to each area later.

Figure 8.11. Divide the foot into specific areas.

Leave the belt intact, since it was created from a basic cylinder that has not been altered enough to destroy its initial mapping coordinates.

With separation of the main body completed now, let's see what needs to be done to her head.

The main head will be fine as it is; a simple cylindrical or planar map will work well here. So let's concentrate on the inner mouth, along with her eyes, teeth, and tongue.

1.

Detach the inner mouth (Figure 8.12) and the ear (Figure 8.13). We do this because both these areas can initially be planar-mapped.

Figure 8.13. Separate the ear.

The inner mouth will need only a simple texture, perhaps a gradient running through it. The ear will benefit from a simple planar projection.

2.

Both the eyes will be handled the same, so delete the one on the right side.

3.

We don't need to do anything to the teeth. Like the belt, the teeth were created from cylinders and so should still retain some good mapping. You can also leave the tongue as is, because it's a basic shape (Figure 8.14).

Hair Division

The inside layers of Kila's hair were initially made from individual strips of polygons. Therefore, this part of the hair should retain its basic mappingif we texture one strip with particular mapping coordinates, they will exist in the other strips.

Using this method will save texture space and, since the inner layers are not fully visible, we should be able to get away with repeating the texture. If, on the other hand, the texture looks obviously copied, we can apply a cylindrical map to the layers.

The outer layer of hair is a different story. No usable mapping exists on it because we have drastically edited the topology. But we only need to do a couple of things to prepare the hair.

1.

The best approach for the outer hair is to first split the hair down the middle, as shown in Figure 8.15.

Figure 8.15. Split the hair into two halves.

2.

Separate the inner polygons from both sides (Figure 8.16).

Figure 8.16. Detach the inner polygons.

Kila is now prepped and ready to be mapped. Clean up the geometry by deleting the history, and save the file as Kila_Divided.mb.

Grae

Grae is a more unique character than Kila, but a lot of the same principles will apply. We will now take the same steps with the Grae model, getting him ready to apply UV mapping.

Start by loading the file named Grae_DeformTest.mb. As you did with Kila, take some time to check the model for any last-minute changes.

Wings

We will initially hide the wings and concentrate on the main body of Grae.

You may be thinking that we could delete a wing, mirroring the other one across. We could do this with ordinary wings because the mirroring would not be obvious. However, Grae's wings are made up of tendrils and should not look identical. What we can do is leave the wings until last, applying them to a separate texture page. Then we can judge whether we have the space to map both separately.

So for now, go ahead and divide up the body.

Leg Division

With the wings hidden, the first area of Grae's body that stands out are his legs. Looking back to our concept drawing, we can see that the upper thigh sections differ in surface design and thus will each need separate mapping. The lower legs, however, are the same, which allows us to use identical mapping techniques.

1.

As shown in Figure 8.17, detach the lower legs and delete the one on Grae's right.

Figure 8.17. Detach the lower legs.

2.

Because all three toes were initially created out of the same piece of geometry, we can delete the outer two and concentrate on the central one. Detach all three toes from the main foot (Figure 8.18), separate the toes, and delete the outer two.

Figure 8.18. Separate the toes, deleting the outer two.

3.

As is, the lower leg section is too complex to achieve clean mapping; breaking it up will simplify the process. Detach the lower section of the leg, as shown in Figure 8.19.

Figure 8.19. Separate the lower section of the leg.

The lower legs can be cylindrically mapped, leaving the upper thighs to be mapped with the torso, so let's look at that area next.

Torso Division

Let's begin our work on the torso.

1.

Select and detach the arms (Figure 8.20). This will leave us with the main area we want to work on.

Figure 8.20. Detach the arms.

2.

We can map Grae's upper body and thighs much the same way as Kila's torso. Separate the front and the back (Figure 8.21) so you can later apply planar mapping to them.

Figure 8.21. Split the upper body into the front and the back.

3.

Detach the head (Figure 8.22) and then the inner mouth (Figure 8.23). You could split the head down the center, mapping one half and mirroring it. In this case, though, leave the head intact, because the texture may need to be different on each side.

Figure 8.23. Separate the inner mouth from the head.

4.

Separate the upper and the lower teeth so that you can map them independently (Figure 8.24).

Figure 8.24. Separate the upper and lower teeth.

NOTE

Because the upper and lower teeth aren't physically connected, you can simply go to Edit Polygons > Separate to detach them.

This is all we need to do to the upper body area for now, so now let's edit the arms.

Arm Division

1.

Following Figure 8.25, first detach the hand and then the upper arm. (The arm itself is bent much more than Kila's was. Detaching it will make it easier to map.)

Figure 8.25. Divide the left arm into sections.

2.

Separate the spikes from the upper arm (Figure 8.25, right), since these can be mapped separately.

3.

Moving on to the right arm, divide it up into the same workable sections.

4.

To finish up, divide both hands into top and bottom sections.

Grae is now divided and ready to be mapped. Save the file as Grae_Divided.mb.

With both models prepared, we can move on to apply mapping to Kila and Grae. We will use tools already mentioned in this section, as well as get our first introduction to the UV Texture Editor.