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3D Monster
CREATING REALISTIC ORGANIC CREATURES IS ABOUT THE HARDEST THING TO DO IN 3D. THEY CONTAIN NO STRAIGHT LINES, THEY’RE FULL OF COMPLEX CURVES, THEIR SKIN IS OUTRAGEOUSLY COMPLICATED AND TEXTURED IN MANY DIFFERENT WAYS — IT’S A NIGHTMARE, AND THAT’S EVEN BEFORE THEY START TO MOVE! THIS MONTH WE’RE GOING TO ATTEMPT THE WHOLE PROCESS, FROM CONSTRUCTION RIGHT THROUGH TO ANIMATION...
Stage One: Molding the monster
First, well create a realistic monster mesh that looks like a real creature, to be manipulated and animated later. |
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1 Before we start any complex models, it’s definitely worth amassing a few photographs for inspiration. Obviously our monster doesn’t actually exist, but dinosaur skeleton images or photos of rhinoceroses and hippos downloaded from the Net is a very good starting point. A few sketches loaded into your 3D program as backgrounds can help. |
2 We’re using the MAX plug-in MetaReyes to create our creature. This enables us to create simple muscle shapes defined by a series of oval cross section. The clever part is that when the creature is rendered, these muscles will mould fluidly together, creating organic-looking contours. |
3 As with any artwork, it’s good to start with an outline and flesh it out slowly. Here, we’ve created a single long muscle to provide the spine of the creature, and are beginning to add the most significant shape-giving muscles. |
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4 Muscles can be created quickly with a few clicks, and then edited to form the right shape. It can take a while to get used to how this works; the early stages of a model can be frustrating, as you don’t know exactly what you need to achieve with each muscle. |
5 To render the muscles you’ll first need to group them. Here we can see the body taking shape. Adjusting the detail of the model as it is rendered will alter the definition of the muscles. We can also change the hardness (which is signified by the color ), so shapes stand out from the skin. |
6 Now we begin to work on the detailed features, using smaller and harder muscles. The monster is becoming quite complicated, so we’ve set the muscles we’re not working on right now to wireframe mode — the display will now update more quickly. Notice that we’re only creating half the creature, because it’s supposed to be symmetrical. |
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7 The face requires special attention, especially, around the eyes, as this is where people will tend to look the most. We’ve used a lot of small muscles to describe the wrinkles around the eyes and the mouth. Try to think where muscles would appear on the real creature, then place them accordingly. |
8 Muscles that are grouped together will stick together; members of separate groups won’t. We’ve used one group for the upper jaw and one for the lower, and the muscles at the back of the mouth are members of both groups. This makes certain that the mouth joins at the back, and not at the front. |
9 Finally, we create a mirror image to complete, the monster’s body. These new muscles must be in the correct groups. Hit Create Mesh to make a single, smooth mesh, then save it as a wireframe. We’ve also applied an Optimise and a Relax modifier to reduce the polygon count for easier rendering. |
Stage Two: Skinning
Our monster has a complex shape. We need to give it a skin that fits and looks realistic two difficult challenges. |
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10 Here’s what happens if you wrap the creature in a simple planar map the shape’s complexity causes parts of the skin to smear. Texture mapping projects a texture from a given direction, so any parts of the object flat onto that projection get good sharp mapping. Anything facing to the side will be distorted.
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11 What we need to do is break our model up into simple parts, map those parts, then reassemble them. There are a couple of ways of doing this. Here we are just detaching parts of the model as separate objects, then applying a planar image map to each part.
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12 Now to the difficult job of detaching the inside of the mouth. It took a while to pick out the polygons from inside the monster’s throat, without selecting on the lips or jaw. In MAX it helps to select and hide parts of your model before you start, then use the Lasso tool to add to your selection.
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13 Once each detached part is given a mapping direction, whatever texture we create for it will be mapped perfectly. We’ve used only planar mapping, because the other types of projection tend to make it difficult to accurately place features onto your models. |
14 To create the texture, we first need to render a flat wireframe image of the body part, with the camera looking from the direction the map will be projected from; in other words, a flat-on view of the portion of the body we are creating a map for. This will create a blueprint for the texture.
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15 Closing our 3D program, we now import the rendered image into Photoshop. This becomes the background layer of our skin. We know that if we paint or clone features onto this background, they’ll appear on the right positions on our model.
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16 We’re using photographs for the skin, mostly of a rhinoceros. The image has a range of different skin textures there are lumpy parts, smooth parts, and patchy colors all over the rhino’s body. Now, using a soft edged cloning brush, paint some different textures onto various parts of the monster.
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17 Using the Airbrush and a dark color, lines are drawn on the face to add character. These don’t look good yet, but will work when applied as a map. The only parts we need to worry about are the joins between different textures keep the parts similar colors at the edges so the blend isn’t noticeable.
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18 Finally, the monster is joined together using the Attach function, and the textures are applied. We use the same map as a color map and a bump map for the creature, giving its skin a lumpy look. It’s a good idea now to scale the creature we’ll be applying a cloth modifier later which depends on the creature’s size, so make it large for a more realistic animation.
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19 The first job is to build a bone structure. This is simply done in MAX- just create the most basic skeleton possible. We use the creature’s rear pelvis as the highest point in the bone hierarchy, and the tips of the feet, head and tail as End Effectors (MAX’s term for the end of a chain of bones). If you move the end effector the other joints should follow.
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20 To ensure realism, the skeleton has to be limited. You can set limits for the motion of any bone — this means looking at every joint in the body and deciding how it would bend in real life. The knees, for example, obviously don’t bend backwards, so we set them to go from 0-100 degrees in the x direction, and make them unmovable in the y and z axis.
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21 Now, we have to use Character Studio’s Physique modifier to mould the bones to the body. Selecting the body skin, link it to the base of the skeleton. After a while, Physique works out which vertexes need to attach to which bones, so when you move the bones the skin moves realistically with them.
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22 This only works on the simplest model, so you’ll need to move to the sub-object level and edit the ‘envelope’ for each bone. The envelope defines the way points on your model move with bones. The points in red will move wherever the bones do — the other colors move less so the skin stretches evenly. Make sure that each envelope covers the points which need to be moved with it, but none of the others.
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23 Problem areas are around the mouth, frill and feet. To rectify these, move the bones, observe which points move when they’re not supposed to, then go back and alter the shape of the envelopes. Next, hide the creature mesh. This makes everything faster and easier to work with again (quite a relief, too).
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24 We need an organic animation, and key framing IS a tricky way to do it. One of MAX’s overlooked features is its Motion Capture function. By setting the motion of the foot to respond to mouse movement, we can play an animation sequence by moving the mouse and record the movement to the position of the foot. The rest of the creature’s leg should follow do this with each foot for a realistic walking motion.
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25 Now to make the body wobble using the ClothReyes plug-in, which is normally used to simulate fabric. One of ClothReyes’ most useful features is its ability to make different parts of an object behave more or less like cloth, depending on their colour. Create a new color map, in which the soft parts of the creature (the belly and the flaps around the legs) are white, and the rest is black.
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26 With this applied, we set up the monster as a ClothReyes object. There are various settings to make the skin behave in different ways, but we’re using a large, thick cloth, so the monster’s skin swings and folds slowly. Now run the ClothReyes simulation. This can take hours or days, depending on the complexity of the object and length of the animation.
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27Finally, the black and white skin used by ClothReyes is replaced by the texture we designed earlier, and the monster is lit and rendered. To add realism, we’ve used several lights, one of which is set to be extremely bright to bleach out parts of the model. This helps avoid the ‘perfection’ that computer-generated shots so often suffer from.
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| Copyright © 1999-2005 Divisionbell. - Hollywood, Ca |
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