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I have recently figured out some key secrets to success in creating dynamic hair in Carrara. Some of these principles may apply to other programs as well. In this article, I will share two secrets for designing dynamic hair that will collide properly with objects during a simulation or draping, thus avoiding the problem of hair going right through objects.
One problem that you have doubtlessly run into working with dynamic hair is your hair going straight through a character's ear or shoulder upon rendering. Of course this can happen when your guide hair goes through the object in question. In that case you just need to make sure your guide hair does not do this, but this is not the problem I am talking about. I am talking about when you drape your characters hair, all of the guide hairs lay in the appropriate places, and you think everything is going just fine, but then, when you render, there is hair going right through the character anyway. What is going wrong?
Well, the answer lies in how the guide hairs work. The hair is filled in between/around the guide hairs via interpolation. The guide hairs are the only thing that detects collisions with other objects. If you place an object between two guide hairs then the hair will just go right through the object. This often is a problem if you have hair falling on both sides of an ear or both the front and back of a shoulder. A similar problem results when there is space between the edge of a growth region and the nearest guide hair. In this case, the hair growing in that space between the guide hair and the edge of the growth region will wind up going through any object that gets in its way. This problem shows itself when you attempt to drape hair along a character's back and shoulders. These two similar problems have their solution in two different principles of dynamic hair design.
The second problem can be solved by knowing where to place your guide hairs. When you are creating dynamic hair, you might be tempted to just let Carrara fill in guide hairs at random, but if this is long hair, rather than fur, this is not a good idea. It is significant where you put those guides. You must have guides all along the edge of your growth region. If there is not a guide at the edge of the growth region, then there is nothing for an object to collide with when it approaches the hair or vice versa. The result is what I described before: hair going through the character's back and shoulders. Even though the guide has draped across the shoulder, the generated hairs just fill in that space between the guide and the edge of the growth region. If you place your guides all along the edges, then this will not happen. There are reasons for filling in guide hairs throughout the middle of the hair as well, but that is beyond the scope of the problem I am discussing now.
The first problem I described is more complicated than just knowing where to place your guide hairs. No matter where your guide hairs are, it is still possible for an object to be between them. If this is the case, again, we have generated hairs moving through the object because the hair is being generated to fill the gap between these guides. What we need is a way to tell the hair to fill the gap between some guide hairs and not others. The way Carrara allows us to do this is via "grouping." there are two kinds of grouping in Carrara: manual and auto-grouping.
Manual grouping means that you define independent growth regions, called "hair groups," as part of the same hair object. The effect of doing this is that the hair in each group fills in the hair only between its own guides, not considering those of other groups. Consider the case of a character with long hair that falls both in front and in back of the shoulder. If all of this hair was defined as a single group, then the generated hairs would go right through the shoulder. If, however, you define the growth region for the hair that falls in front of the shoulder as one group and the growth region for the hair that falls in back as another, then you no longer have this problem.
Auto-grouping means letting Carrara decide how to group the hair when it is generating it. In the properties for the hair, you can enable auto-grouping and set the conditions by which Carrara decides how to group hair. I find that the most important condition is angle. Using the angle condition means that if two neighboring guide hairs are pointing in significantly different directions, then there will not be hair generated between them, just as if they were in different groups. This allows you to part hair. You can use this for parting bangs or separating the hair on two sides of an ear or shoulder. The value of the angle condition determines how different the angle must be. Smaller values mean that the angles must match more closely. The great thing about auto-grouping is that it is dynamic. Unlike statically defined groups, when the hair comes together and you want it to act as a single group, it does.
By placing guide hairs all along the edges of your growth regions and using grouping appropriately, you can avoid these mysterious and annoying problems in your dynamic hair. Each situation may call for a different guide configuration, depending on how objects in the scene might be interacting with the hair, but these are important principles to start with. With this knowledge, hopefully, you can design hair that will work in a wide range of situations.
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Last Updated on Thursday, 18 November 2010 22:06 |
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If you are like me, you have seen your share of giant robot anime. If you just take a random sample of anime movies, OVA's, and series, chances are that a significant percentage of these employ some kind of mecha as a part of the story. Also, if you are like me, you will agree that there are some giant robot shows that are great and some that are just not worth watching. So what makes the difference between a classic, like Gundam, and something altogether forgettable?
There are several answers to this, of course. All of the standard questions about what makes a good show apply to this genre, and I don't really want to go into that. This site is about animation and I want to talk about a specific observation that I have made about what really appeals to me with giant robots. This can be summed up in one word: scale.
The thing about giant robots is... they're giant. For me that is key. In fact, the series that first made me realize that there might be something to this whole anime thing was Mobile Suit Gundam: The 8th MS Team. This was on the Toonami Midnight Run back in the good old days, and I remember just catching it at the right moment to see a scene that made an impression on me. There was a girl at the top of a cliff, and I think she was lying down with a pair of binoculars keeping watch. Then, to the girl's surprise, a giant mobile suit (I think it was a Zaku), which had been hidden from view, walks right in front of her at the bottom of the cliff. The mobile suit's feet were at the bottom of the cliff, but the head rose above the top of the cliff, such that the girl, and the camera angle, was at about the height of the head. This really produced a feeling of just how large those mobile suits were, and the animation was executed with enough realism that it really gave me a sense of awe.
This is what made me stop and say, "Wow, that was well done. There really might be something to this." If I am just watching two robots fighting each other in space, with no significant sense of scale, then it is kind of boring. It may as well just be two people duking it out in the old west. Sure its an action scene, but not a special one. In fact, without that sense of scale and realism it becomes just what non-anime fans think from hearing a description. Its just silly.
There are people that will watch anything that looks sci-fi and be happy, because they think it looks cool, but if you want to appeal to a wider audience, you need to do more. You need to visually communicate the monstrous scale of the machine in a way that will strike awe in the viewer. Its not enough to just have people talk about how big it is. In fact, its not really enough to just show it standing next to something smaller. You need to be creative with your perspective, sound, and animation to really make the viewer feel what it would be like to stand next to something like that in real life. This also requires a certain realism in your presentation. Make the viewer feel that the giant mecha they see on their screen would be very similar if they saw it in the real world around them.
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Last Updated on Wednesday, 17 November 2010 20:11 |
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I have spent some time trying to research the best way to create anime hair in 3D, and I am finding that there is not just one answer. In fact, in Carrara, there is not an answer that I like. Let me explain:
There are at least three ways to make 3D anime hair:
- Hair Siimulation
- Modeled Hair with Soft Body Physics
- Modeled Hair with Rigging and Rag Doll Physics
- Modeled Hair with Rigging and/or Morphs
All three of the other options start with modeling hair, which can produce a nearly perfect anime appearance, although that is a trick in and of itself. I'm not going to analyze the sort of model structure that works best right now. I'm more concerned with how I'm going to animate it later.
The first of the remaining options is modeled hair with soft body physics. I actually think that this is the best way to do cel shaded anime hair in 3D. This way you can construct a model that will render like the clumpy 2D hair that we are used to seeing, but you can still do a physics simulation to get the hair to respond in a realistic way without having to painstakingly animate it. Now, its true that you can't beat key frame animation for overall effect in character animation, but we are not talking about moving arms or making facial expressions here. We are talking about hair blowing in the wind or swinging after a movement of the head. There is not really a need to key frame something like that if you don't have to. It really should just follow the laws of physics. Carrara, however, only has soft body physics in BETA form in Carrara 8, and its too buggy to be used in this way.
Since Carrara does not have a usable soft body physics, the last type of physics simulation that could help with the situation would be rag doll physics. If the hair was rigged, then rag doll physics would allow the hair's rigging to be affected by gravity and other forces in the scene. This would be pretty good too, but this is something that Carrara does not have at all.
This only leaves one method available. Since I can't use physics, I have to key frame animate the hair. I can do that by rigging the hair model, by assigning convenient morph targets, or both. Rigging seems to be most desirable for basic motion. Simple rigging too, so you can animate the motion of the hair as easily as possible. Morph targets would add something very useful, though. You can probably achieve some deformation of the shape with morph targets that you could not with rigging alone. Also, a morph target might help with a complex movement like blowing in the wind. Two or three morph targets to preset the key frames for that common scenario might help a lot.
In this way, Carrara has an annoying weakness that applies directly to what I do. It is enough to make me think about other software again. I love Carrara, especially the rendering engine, but it would be nice to take advantage of Poser's well developed cloth simulation or rag doll physics plug-in. I suppose if I forked out a small fortune for Maya or 3D Studio, then they would also have a physics simulation that would work for me, or maybe something better that I am not even aware of. I have tried simulating cloth in Poser and exporting it to Carrara, but I don't know a way to make that work. If I could not make that work, then I am stuck choosing between Carrara's rendering or Poser's cloth simulation.
On the other hand, though, key framing the hair is not so bad. After all, it does give you the most control, and it is the way traditional anime has been doing it forever. Maybe that is just the way to go. For now, that looks like the way I am headed with the hair I am planning. I will rig it in Poser, though. There is no sense in rigging stuff in Carrara when Poser rigs are compatible with Carrara and anything that supports the Poser content library.
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Last Updated on Wednesday, 27 October 2010 21:42 |
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I have added a new section to the site to focus on my primary interest: 3D anime, especially cel shaded 3D anime. In the new section, you will be able to find a catalog of resources to help you in developing 3D anime, including 3D software, plug-ins, content, and tutorials. Also, since good examples of 3D anime seem to be sparse on the internet, there will be featured art and animation, mostly from independent artists like myself and so many of you. Please check it out, and check back regularly for updates.
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Last Updated on Wednesday, 27 October 2010 21:42 |
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Well, I've finally gotten to the point where my website is at least halfway working. I just don't have the time to dedicate to getting all of this set up the way I want. For now, this may have to do.
Today I got the CSS customized sufficiently that it no longer looks totally generic, and for now, I am happy with that. The header image took some time to do. It is a good representation of my artwork, though, since it shows a 3D anime girl rendered four different ways:
- Cell shaded
- Photorealistic, but with a cartoon-like texture
- Photorealistic with a realistic texture
- Wireframe
Hopefully I will be getting some info up on the site soon.
Check back.
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Last Updated on Saturday, 10 July 2010 14:51 |
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