CAP 201a - Computer Animation I

Lesson 8 - Chapter 11, Textures and UV Workflow



Chapter 11 introduces more features of the Material Editor, among them the Slate Material Editor mode. Objectives important to this lesson:

  1. UV Unwrap
  2. Slate Material Editor mode
  3. Seams
  4. Bump map and specular map

A model that has a complex shape will often require you to create a custom map that will fit only that model. We approached this idea when we custom fit an existing map to the Red Rocket's fin in chapter 10. In this chapter, we will see that the process can be much more customized.

Project Exercise 1: UV Unwrapping 

This exercise starts on page 226. Before you begin it, set your project folder as directed and open the supplied file named on that page. Upon inspecting the file, you may note that the authors have added knee pads and elbow pads to the soldier model, as well as straps supporting them, another pouch near the holster, and perhaps more that I am not noticing at this moment. A reason to go with their version this time, is that the directions for the next steps depend greatly on the model itself. You may be able to extend the lessons to your own model after working with theirs.
In this chapter, save often. If you make an error that is too far back to undo, your only choice is to reload a saved file.

  1. The exercise starts by telling you to turn on Smooth+Highlights+Edged Faces by pressing F4. (F4 only affects Edged Faces.) This was already turned on when I opened the scene, but the instruction should remind you that F4 is a toggle button. If it turns off the feature you want, just press it again.
    The text also tells us to turn on the Realistic mode if we are running the Nitrous driver. This enables a shadow enhanced model, which is different from Shaded mode.
  2. Subobjects for Unwrap modifierSelect the model, open the Modify panel, and add an Unwrap UVW modifier to the stack.
  3. Click the plus sign for the Unwrap UVW modifier to open its subobject list. Select Face subobject mode. (As shown in the image on the right.)
  4. The text directs you to make a change on the Configure rollout of the Modify panel, You will not see that rollout at first, because it is the last rollout at the bottom of the panel. Drag the panel up until the Configure rollout appears. Do not click any unwanted button while dragging the panel.
    Turn off the check box for Map Seams. Note, as the text says, that this will turn off the green highlight that was on your model.
  5. Point to Point Seams buttonThe text tells you where to look for the next button, but it is wrong. If you have dragged the current modify panel to find the Configure rollout, you should look next for the Peel rollout, which will be near the top of the current layout. (Dragging panels is probably why someone invented the Graphite ribbon.)
    On the Peel rollout, find the Point to Point Seams icon and click it. The icon art may make it hard to tell that I am holding my mouse pointer over the second icon in the Seams group in the image on the right.
  6. To understand what you are about to do, consider the shirt or top you probably have on right now. (If necessary, politely look at someone else. No, lady, I'm an artist, not a pervert.)
    On most garments, there is a seam that starts under the arm and runs up in front to the top of the shoulder and down the back of the shoulder to where it started. Another seam starts in the same place, but runs along the under side of the arm toward the wrist. You are going to use this tool to make seams just like that in the model. You want the seams to run along the edges of existing polygons. Remember, you are not cutting edges in the garment on the model, you are establishing seams in the surface of the model. Seams are logical places to unwrap the skin of the model, so a version of the skin can be painted in Photoshop or some other art program.

    Look at the illustration on page 227. Click at a vertex like the one shown in the picture on the left on that page and continue clicking on vertices in a line up to the top of the shoulder. A blue line should form, showing edges where you are cutting a seam to unwrap the model. (You will not not see the dashed line that the text says will appear if you drag, only if you click a series of points.)
  7. Orbit the model, and continue clicking from your last vertex to the next to complete a half loop from the armpit to the top of the shoulder.
  8. Continue orbiting and clicking to extend your seam back around to the point where you started.
  9. Orbit to a position where you can see the under side of the model's left arm. Turn on the Point to Point tool, if it is off. Click from the seam you cut, along visible edges, to the end of the wrist. Right-click to stop drawing the new seam.
    The instructions are little light here, but there is one more point to click
    The seam has to run to the center point of the cap of the wrist. You can't see that vertex because the hand is in the way. Time for something new: wireframe.

    Wireframe of seam to wrist

    Change to wireframe view of the scene. Get your bearings, and figure out where you are. Orbit and pan as needed to see both the current end of your blue seam at the edge of the wrist, and the center point of the wrist cap. Click your last vertex on the blue line, and connect it to the wrist cap center. Then, right-click to stop making the seam. In the image above, I just did that. Turn off wireframe view to keep your sanity.
  10. In step 10, you are told to repeat the seams, this time on the model's right arm. Do that, so you have similar seams on each arm, including the line to the wrist cap center.
  11. Refer to the second picture on page 229, but ignore the yellow edges. Look also at the blue line in the second picture on page 230. (Magnifying glass time, again.)
    Starting on the model's left side, extend the under arm seam down the side of the model to the top of the pouch. However, note that you are to outline the Kevlar cutouts using their inner edges. This will not help much if there is no connection to the existing seam, so connect it like the image below. Once again, I am in wireframe view to see as many edges and vertices as possible.

    Seam down sides and around belt

    Continue the seam around the belt line closest to the body. Run the seam above the pouches and holster, not through them.
  12. Cut seams on each of the gloves as directed in the text. Note that the gloves end inside the wrists in this model, so you will have to use the wireframe view to see the first and last vertices for the seam on each hand.
  13. Standard Material nodeFinally, the text returns to the Material Editor. Open it, and switch to the Slate Material Editor.
    The text directs you to look on the left panel (Material/Map Browser) to find something. The first rollout is called Materials. In it, the next rollout is called Standard. In that rollout, find the Material template called Standard. You can double-click it, as the text says, or you can drag it into the middle (Active View) panel. (Called View1 at this point.) The text tells us that what opens is a Standard Material node.

    The node (shown on the right) has a set of round connectors (sockets) on its left side for input from other nodes, such as map files. It also has a socket on its right side for output to other nodes. Using these sockets to connect to other maps and materials, nodes can be highly modified.
  14. The text tells us to double-click the input socket for Diffuse Color. When you do, a new window opens. The text says the Material/Map Browser opens again, but there is a difference. The new one does not have a rollout for Materials: it expects that you want a map. Under Standard maps, select the Checker map and click OK. (This is a map supplied with the program that resembles a black and white checkerboard.)
  15. You can pan and zoom in the Active View panel to see that two new nodes just attached to our Standard Material node. Each has a title bar. The text says to double-click the title bar for the Checker map. This opens a parameters panel for it on the right side of the Material Editor. The first rollout on that panel matches the picture on page 233.
    Follow the instructions in the text to change the Tiling values for the map from 1 by 1 to 5 by 5.
  16. Drag from the output socket of the Standard Material and drop on the model. You will not see the material in the workspace yet.
  17. As you had to do in the Compact mode, to see a material in viewports, you must click the button on the Material Editor's toolbar called Show Shaded Material in Viewport. Why does it say shaded? In this sense, a shaded material is any material that is not just a basic color. Connecting a map to a socket for your material made it a shaded material.
  18. Save your file with a new name, and don't get depressed by the way the model looks right now. The material is not mapping correctly yet. We will address that on the arms in the next exercise.

Project Exercise 2: Pelting the Left (and Right) Arm UVs

Continue with your model from the last exercise. The text tells you at this time that the reference image objects are hidden in the scene, but you can unhide them if you want. It gives no reason to have a preference, so leave them alone for now.

The images in the sequence below are from working with the model's right arm. You will have to do both arms, one at a time. You can start with either one, but the text starts with the model's left arm.

  1. Select the model. Go to the Modify panel, and select Face subobject mode from the choices under Unwrap UVW in the modifier stack. Make sure Point to Point Seam is turned off. Click one face on the left forearm of the model as instructed. Click the Expand Face Selection to Seams icon, which is the icon on the end in the same line as Point to Point Seam. The faces on the arm should all turn red, like the picture at the top of page 234.
  2. Right arm before being peltedStep 2 says that we need to unfold the the UVs to create a usable pattern or skin. The word the program uses is pelt. The text says to click the Pelt Map icon in the Peel rollout to do this. Do it, and have patience. You are only getting started. The horrible sight in front of you will improve in a few steps.
  3. Two dialog boxes will open, like the ones shown at the bottom of page 234.
    The Edit UVWs dialog box is the bigger one. On it, open the View menu, and look for Show Grid and Show Map. Make sure both are turned off. This will simplify your view a bit.
  4. Pelted right armOn the Pelt Map dialog box, find the Start Pelt button, which should be on the top left corner of the box.

    Click it, and wait for a few seconds. If your processor is slow, it will not complete the job instantly. When the pixels stop moving, click the same button which now says Stop Pelt. My pelt for the right arm at this stage is shown in the image on the right.
  5. The squares in the checkerboard don't fit yet. Find and click the Settings box next to the Start Relax button. Open the drop down box in the next dialog box, and select Relax by Face Angles.
  6. Pelted and Relaxed by Face anglesYou can click Start Relax in either the box that just opened or the last one. Again, wait for it to finish. When it is done, close the Relax Tool dialog box.
  7. Click the Commit button at the bottom of the Pelt Map dialog box. This saves the change to the model in memory. (It does not save your scene file.)
    Close the Edit UVWs dialog box. There should now be a recognizable checkerboard pattern on the arm you pelted.
  8. Save incrementally.
  9. If you just did the left arm, repeat the entire process with the right arm. Save incrementally again when done.

Compare the unpelted image to the final image and you should see that the final version will be much easier to paint.

Project Exercise 3: Unwrapping and Using Pelt for the Head

The next exercise works on the head, onto which you merged goggles, mask, and helmet in your model. As we will see, the authors have merged another object, a helmet strap with one piece on either side of the helmet.

  1. Note that the text tells you to save before you do anything in this exercise. Not that anything might go wrong, but... I have a bad feeling about this.
    Select the soldier. Go to the Modifier stack. Open the Editable Poly object, and select the Element subobject.

    Before you can make that last selection, the program should give you the warning screen shown on page 237. When you see this warning, and you will see it again, think hard before going on. In this case, the text tells us this is a safe operation. You are going to select the object lower in the modifier stack (causing the warning) in order to select an Element subobject. Your intent is to select a piece of the model, but not to modify it at that lower level. Modifying at lower levels in the stack can cause unpredictable results.
  2. Choose Element subobject level, then select the helmet. With the helmet selected, go to the Graphite ribbon, find the Visibility tab, and click Hide Unselected. Everything else on the screen will disappear.
  3. Return to the Editable Poly level by selecting it, then select the Face level in the Unwrap UVW object. You are now back to a facet of the top level object in the stack. This avoids making a change in the lower level object.
    On the Peel rollout, select Point to Point Seam again.
    Refer to the picture on page 237, and make a seam on the helmet to match the yellow line in the picture.
  4. Trust me: save again now, if the helmet went well.

    Proceed with the instructions here to put seams on the goggles. Do the seam on the front of the goggle between the goggle frame and the glass first: it is easier. When complete, save incrementally again. As you do the seam that is displayed in the lowest of the three images on page 238, you will learn that you cannot cut a seam from the inside of a model element, only from the outside, which means you will have to orbit the model from cut to cut, maintaining contact with the outside edges of the model. Another way to think of this is that you cannot cut a seam unless you are on the Normal side of a polygon.

    Blue line behind goggles is the seam of the helmetAn interesting challenge to cutting the seams on the goggles is that you will continue to see the seams of the arms, hands, torso, and helmet as you do so. The helmet seam may be confusing, so make sure each edge you cut is one you actually want to cut. The good news is that every time you switch to another subobject, you can see the seams you cut for the last one. If you are merely missing some seam edges, you can go back to that subobject and cut the seams, now that you know where they are. (Draw a picture first? Take a picture? Don't lose your way.)

    A question that I anticipate coming up at this time is "Do I have to cut every edge in a strip of edges? Can't I skip ahead and cut every other edge, or every third edge, and let the software fill it in? It seems to do that."
    You could try that, but it is a bad idea in an environment where some of the edges and vertices are not visible. Eventually you will miss an edge, connect a vertex to the wrong place, go beyond the level of undo steps, and have no way to correct your error but to go back to your last save and start over from there. Been there, done that. Don't go there. You will look for ways to expand your profanity vocabulary at a moment like that.

  5. If you finished the goggles, save again. Begin the task of seaming the mask by looking at the two rather small images at the top of page 239. You will do better to look at what the authors did.
    You just saved, right? It is safe to open one of the authors' later files to look at the seams in it. Don't change anything in their file, just look at the seams for the mask until you understand what they want, then come back to your incrementally saved file.

I got the mask to work, played with the head until it worked, then went for the helmet straps. Then the model got very uncooperative. In the interest of time and sanity, browse through several pages with me before we hurl the book at the wall.

  • Beginning on page 240, the text asks you to seam the rest of the body according to tiny diagrams on page 241. Let's assume it would have been possible if we were given decent instructions and illustrations.
  • Page 242 begins pelting the parts that have not been pelted yet. This is just more of what we did for the arms. Note the stack of pelts in the picture on page 245. Every pelt you make is just piled on top of the rest until you move them. That is what the Pack Normalize button, shown at the bottom of page 245, is for.
  • The picture on page 246 shows all the pelted and relaxed UVs for the model, arranged in a space saving layout. On page 247, the Edit UVWs window has been rendered. The render window has an option to save the current image as a file. Once saved as a file, the template can be opened in a paint program, and a texture map for the model can be created. It is important that no further rearrangement of the pelts take place in the Edit UVWs window once you decide to create a texture map from that layout.

That is enough of this chapter for now.