Sunday, 29 November 2009
Saturday, 21 November 2009
One of the things that I am a bit disappointed about is Vue's plant editor. There is one, but it is fairly limited: it will let you alter existing designs, but you cannot design completely new shapes with it, and if you want alien forms, you need more freedom that Vue gives you. Of course, there is XFrog: it will allow you to do that, but it is difficult to learn and for several years now all development efforts have been directed at versions to be used with major 3D packages, leaving general users like me with the 3.5 version, that is by now rather old. Still, you can design very interesting shapes with it.
Animation is another subject that Vue must be able to do, as there are breathtaking demonstration videos available, but unfortunately most general users find it extremely difficult to get good results. In experimenting with animation I was not too disappointed, but my standards for animation might not be that high. It is possible that the latest version of Vue is better, but I am at least one version behind.
So here are two scenes from a very quiet swamp. The reasons it is so quiet is twofold: I should add some sounds, but I have never create an alien nature sound track yet. I do have ideas on how to do it, but it does not have a high priority. The other thing you will notice is that the plants and the water do not move at all. Vue can actually produce plants that move in a breeze, but that works only with its own type of plants, not with imported objects.
You can find the same swamp in the plants section by the way.
You may well find that the scene isn't that alien, and you would be right. I am guessing that branching plant shapes would converge in design across the universe, but I could have thrown in a few mixomorphs or ballooning plants to spice up the scene. Then again, there are items you cannot see that well. The 'spirflower' is a case in point. Flowery things are probably universal, in that it makes sense for sessile life forms to entice mobile ones to help with procreation. A flower is just an advertisement. There is no need for them to look like Earth flowers though: any form might do, I guess. The spirflower has two brightly coloured blade-like leaves in a double spiral, with small bulbs on top that exude the reward for landing there (while secreting some sexual cells, of course). Here is one in a close-up, done with Vue.
Sunday, 15 November 2009
Click to enlarge; © Alex Ries
This one image speaks volumes. The first is that Mr Ries really knows his business as an artist (I wish I could paint in such a assured manner). Obviously, you can also see that it is an intelligent species (or at least it has intelligence in the toolmaking sense, and I am not certain that that is enough to qualify). Something else that struck me is what the body plan of the Birrin reveals about its planet. There is no indicator of scale, but the objects and choice of perspective suggest that the Birrin is at least one meter tall. It must live on a low-gravity world. I think so because its legs are rather spindly and stick out sideways, instead of being held vertically underneath the body. On Earth such limb positions only work for animals that are rather small, up to the size of a coconut crab, but most animals with such limb designs are smaller that that.
The reason for this is that gravity affects animals of different sizes in different ways, a subject known as scaling. It is less complex than it sounds. Suppose you make an animal twice as large in the sense that its height, width and breadth are all twice the original amount. The large one will weigh 8 times as much; that is because weight relates to mass, and mass relates to volume, and volume relates to length by a power of three. Now the cross area of its legs will be four times as much as in the original animal, because area relates to length by a power of two. The strength of legs is relates to their cross section, so what we have is an imbalance: the animal's weight has increased more than the strength of its legs. The solution? Increase the cross sectional area of the legs out of proportion. That's why elephants have thick columnar legs held under the body, and spiders have thin ones that can stick sideways. Can you have a large animal with spindly legs sticking sideways? You can, on a low gravity planet. Alternatively, the material the animal is made of are incredibly strong (how about a skeleton of biological carbon nanotubes?). The Birrin doesn't look very small but has thin legs, so I assume it lives on a low gravity world. I wonder what really small animals look like: hair-thin legs?)
Anyway, I cannot resist plugging the concept of 'centaurism' once more; the Birrin looks like its manipulative front legs have evolved from walking legs, so there we are again...
Here is another fine animal, one with (largely) radial symmetry. It is good to know that tetropters and spidrids are not the only animals in the fictional universe with radial symmetry. They have their counterparts in the known universe, with anemones and starfish and the like, but sadly we know of no animals walking around with any degree of elegance. I like the anatomical details of this one. I have no idea whether or not it is supposed to live on the same world as the Birrin.
What an intriguing shape. It is probably so intriguing because it is not immediately obvious what part does what, or why it is where it is. That is what makes it convincingly alien, I think. Is it a passive floater? It has a rather large bladder, apparently larger than a mre swimbladder would require. What are the membranes for, I wonder; perhaps they are a sea anchor to make it fave waves head-on?
This one I found on Deviant Art. This animal is an excellent example of convergent evolution. I do no just mean that it is similar in some ways to seals, turtles or plesiosaurs, with its apparent 'swimming with wings' design. I was thinking about 'convergent speculation', meaning that it resembles a design that someone else has also come up with. In this case that someone is me, but you see this happening everywhere where people sit down with a sketch pad and create new animals (while writing this I hesitated a bit with the word 'create', because creationists have tainted it to such a degree that it is difficult to use without evoking wrong connotations). The animal I was thinking about follows:
Click to enlarge; © Gert van Dijk
See the resemblance? Mine was just a very rough sketch, but it conveys the general idea; they are 'AYUS' (As Yet Unnamed Species) from the 'Fishes IV' class. There are differences too, such as the apparent size differences, with mine at about a meter, and his perhaps at humpback size. But look at the similar design of the mouth parts. Before anyone thinks otherwise, I am not saying that either one of us took the idea from each other's work. That cannot have been the case anyway, as mine was done over 10 years ago and has never been published.
It's a simple case of convergent speculation! Of course there are clear influences to be seen in some people's work pf others'ideas, I think that Alex' work looks all his own. Anyway, there are a limited number of biological principles to go around, so all of us tend to arrive at the same ones, having all been subjected to similar ideas. Luckily, there are infinite ways to arrange such similar ideas (and if that sounds a bit like Mr Spock, so be it).
Be certain to have a look at the websites I mentioned, as there is more to see there. But not enough to satisfy the appetite for more... I hope Alex Ries will be successful in getting his book published, because his work makes me very curious to see more of it.
Saturday, 7 November 2009
In other words, neural control is probably the prime difference between animal locomotion and man-made machinery. 'Control' goes much further than just standing upright or thinking of where you are going. It also affects leg design to a very important degree. Have a look at the following graph.
This is the result of one of my Matlab programs to animate fairly simple legs. First suppose that a leg is suspended, so when it moves its hip will stay in place and the foot will described a movement in the air. The blue dots show 100 points of just such a cycle: in this case, 50 points describe how the foot moves forward (to the left) through the air, and the bottom 50 points describe the part where the foot is supposed to go over the ground. In that section, the foot has to move the exact same distance from dot to dot, and the movement should be in a perfect straight line (anyway, if you do it this way the animation is much easier). The brown lines show a variety of ways how you could position a leg with just three 'bones' in it (thigh, leg and ankles) to link up the same hip and foot positions. Obviously, there is an infinite choice here, and in biology the nervous system decides on the best one, taking into account anatomy, gravity, lengths of bones, etc.
If you haven't got a brain, such as holds for mechanical designs, but you want a walking leg nevertheless, you will have to find a way to get the leg to move through a similar movement arc as shown in the figure above. In short, the degrees of freedom a nervous system can easily deal with must be abolished altogether. The trick is therefore to start with a defined movement provided by a motor, such as a rotary movement, and to devise a system of links and levers to end up with a foot moving though a suitable path. Some people actually solved that problem. Let's have a look.
One of the first must be the Russian engineer Chebishev, brought to my attention by Pavel Volkov (thanks Pavel!). Pavel also pointed me towards the video shown above, an animation of how the system was supposed to work. Here it is in its YouTube home if you prefer that. I have no idea of how this engine was supposed to be powered.
The impressive machine ambling along on the video above is a strandbeest. Theo Jansen's 'strandbeesten' (which is Dutch for 'beach beasts') must be the most famous of this type of walking machine. His designs are marvels of engineering as artistic wonders as well. They have to be seen to be believed (before anyone asks, no, I have never seen them with my own eyes, which is something I should rectify one day).
Personally, I have found that I had to watch it, and others like it, quite a few times before I began to understand how the legs move. Apparently Mr Jansen made use of an evolutionary approach to work towards the optimal proportions of all the struts and links that make the legs behave as necessary. If you type 'Jansen linkage' into Google, you will find that many people are equally fascinated, so the 'Jansen linkage' seems, like any good meme, to be spreading and evolving. If you wish to se it in more detail, have a look at this site, where you can even play with design to see if you can improve the output. His devices have been copied in wood, cardboard, and other materials. There are Lego examples as well.
The one shown above is made from wood. It has a very clever gear system that ensures that only one leg is off the ground at any time. The YouTube text says that this is a stop-motion animation. Its website is here.
There are other approaches as well, such as the Klann linkage. It results in a more spidery walk, as can be seen by a direct comparison of the two linkage systems. This system has spawned several large mechanised walkers, to be found through Google or through the Klann site.
Do these designs lend themselves to 'biologification'? In other words, could I or someone else use them for a fictional animal? I can think of no reason why it should be impossible to have a pantograph-like leg. But why would you want a leg that can describe only one movement? All adaptability and all flexibility are thrown out of the window. If you throw in a fairly decent nervous system instead, you can solve the walking problem and do much more besides. So no, I do not think that this is a mechanical design that would work well in biology.
But that doesn't stop me admiring and enjoying the ingenuity of designs such as the strandbeesten!