Photorealistic spidrid animation (maybe...)

 Now that The Book is out of my hands, I can pick up some old Furaha projects that I had to pause earlier on. I used Matlab, a programming and analysis tool, to produce animations to see how various animals moved. The resulting 3D representations helped a great deal to get a better feel for the gist of the movement and were very useful to get the paintings right. However, I also wanted to produce more lifelike, even photorealistic, animations. Those with good memory may remember that I used to do entire Furahan scenes using a 3D rendering programme called Vue (or Vue Infinite) from the firm E-on. There are some on my rather inactive YouTube channel.  

Producing even short animations proved to be extremely time-consuming. Vue is a raytracing programme that produces very good atmospheric results, but each frame took ages. I used to leave my PC running for one or more nights. The problem with animations is then that you only get to judge the the quality afterwards, and you may then have to do it all over again. 

The main reason I stopped making visually rich animations was that they did not contribute to The Book; by consuming time, they in fact postponed its completion. Another important reason was that programming animations was often frustrating. I could achieve my goals in Matlab, where the problems boiled down to defining rotations and translation of every body part of a radially symmetric eight-legged spidrid walking on uneven ground, with the body attitude compensating for the slope. That was complex in that it was difficult to keep track of everything, but the key parts required fairly basic trigonometry. The seriously frustrating part was to reinterpret the resulting data with Python code to direct Vue. The coordinate systems never really matched up, even if I started with both the y-axes up in both systems and similar handedness orientations of axes (that means whether the positive x,- y- and z-axes pointed in the same direction in both programmes. Even though I made sure of that, I still had to swap y- and z-axes, which in turns messed up all rotations.  

Here is an old example I posted back in 2013. There was a problem with the legs: sometimes the leg segment closest to the body (that wasn't shown) flipped around, so the pale underside is suddenly placed the wrong way. This happened when that segment rotated beyond the vertical position; let's say the rotation angles moved from 85 to 95 degrees. This was almost certainly because a function such as arc tangent interpreted 95 degrees as 5 degrees. At the time, I gave up and shelved the programme. 

I have now tried again, helped by the fact that I now have the latest and much more stable version of Vue. Sadly, Vue's parent firm (Bentley) decided that it would no longer develop Vue at all, so the 2023 version is the last one ever. The good news is that Vue is now available completely free. This version is a pleasure to work with. You do not need to be able to code at all to use it.

Here is a Matlab example of expanded spidrid animation functionality. You can see that the spidrid follows the terrain perfectly, meaning that the body posture echoes the terrain under the body precisely. You can also see something new, present in my spidrid paintings, but not yet in earlier spidrid animations. In earlier animations, the body consisted of one part whereas theyere should be two: a bottom part (the abdomen) that bears the spidrid's eight legs and a top part (the cupola or cephalothorax). The cupola can move on the abdomen. In this animation the copula is stuck firmly to the abdomen. 

In this second example, the abdomen is partly stabilised and no longer follows the terrain completely, so it stays more horizontal than in the previous animation. The cupola now moves independently and has its own tilt-dampening stabilising reflexes, so it stays even more horizontal than the abdomen. That should help the animal get a more stable platform for its senses.

After rewriting the python code the next step was raytracing with Vue. After suffering much misery and new dents in my wall where I banged my head, I got it working. The next phases include adding an abdomen and a cephalothorax, perhaps even feelers, and then it is time to add plants swaying gently in a breeze. 

Wish me patience...

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For those who wish to use Vue, or its associated plant editing software 'PlantFactory', you can download them here. 

As I said, this last version is quite stable. With Vue it is not that difficult to produce an image of a forest with prehistoric trees or something like that. If you wish to have more control over Vue's myriad options, be advised that this is a complex piece of kit that needs attention and time. 

For tutorials, there are several; GeekAtPlay provides good ones. 

Work in progress: A cloakfish documentary, with music!

Cloakfish have featured before in this blog, for instance here and here. With their four undulating fins, the 'cloaks', they lend themselves well to animation. Actually, like some other shapes and ideasm they really NEED animation. The movements of the cloaks are calculated with matlab using trigonometry, and the results is written away as a so-called obj-file and later imported in a rendering program, in my case Vue Infinite.

The animation in this post was one of my last attempts. The movements of the cloaks were calculated with Matlab, which resulted in lots of so-called obj-files that were imported in a rendering program, in my case Vue Infinite. If you look carefully you will see that the cloaks are the only moving part of the animal; that is because the rest is modelled as an unyielding and immobile blob.

The last time I showed such an animation to an international audience was at the TetZoo convention in London in October 2018, where I was given the chance to talk about the Furaha project. Afterwards I met another speaker, Fiona Taylor, who had given a talk on the use of music in nature documentaries. She showed, with examples, how strong music can influence the mood of the documentary, or in fact determine that mood. Here is Fiona's website; she has a very nice blog as well. I recommend that you read part of it, to understand the art and craft of using music for nature documentaries.

We got to talking in the corridors afterwards and she mentioned that, when she saw the cloakfish animation, she starting thinking what kind of music would fit with it. I liked that idea very much; as I have absolutely no musical talents whatsoever, the idea of getting a professional to take care of music was very appealing.

Unfortunately, I was too busy for a year to working on a big project, but that has changed now, so I have starting programming. The new programmes should result in more detail, and in particular in much more control over cloakfish form and movement. Once that is achieved, it should be easy to produce several species of cloakfish and set up scenes. After that, my computer will take over: one minute of film will require 60 times 25, or 1500, images. I would like to achieve a resolution of 1280x720 pixels, but that will depend on how long the rendering takes.

The first item on the programming agenda consisted of better mesh-producing algorithms. A 'mesh', in computer graphics, is a set of connected triangles (or other shapes) that together define a surface. Unfortunately, I cannot make use of ready-made programmes because I have no idea which programme can produce the undulating membranes that define cloakfish movement. I suppose that high-end programmes such as 3D Max and Maya can do so, but one look at their price range is enough to start looking for alternatives (doe any readers know whether Blender can do that?). One alternative, of course, is the old-fashioned hard work approach. Lacking the means to solve the problem using a lazy approach, actual work seemed the only choice left.

I chose to start on another marine animal, a 'crin', a sponge-like sessile lifeform that feeds by filtering sea water. It is simpler to produce. Crins are tube-shaped. Their plankton sieves are hidden away inside the tube. Crins can increase the volume of water they 'harvest' by pumping water actively through its tube. In some form or another they have featured in the Furaha universe from the beginning, even though I never painted one. My present aims were firstly to define it in such a way that I could produce low- and high resolution versions at will; secondly, to deform the body while keeping the mesh structure intact; thirdly, to deform the texture of the animal along with the shape itself. For the connoisseurs: that meant a better understanding of 'UV coordinates' and much better housekeeping of which vertex goes where.  

Click to enlarge; copyright Gert van Dijk

This is an image of the 'Crin Designer', showing how the contour of the crin is initially defined with just a few points, shown connected with blue lines. These are connected by smooth curves, in red, that form the basis of the mesh production. The crin’s 'foot' is supposed to be fastened to a rock or something similar, but here it is just a disc. The tube does not run completely through the animal, but outward appearances are enough for now. I had not realised how much it looked like a wineglass. Perhaps I should call this species "P. grigio"...

Click to enlarge; copyright Gert van Dijk

Here is a high resolution mesh.

And here is an animation, in Matlab, of a low resolution version. The movement worked nicely, even though the water transport should perhaps be in the other direction, with water flowing in at the bottom and out through the top, instead of the other way around. In life, I imagine that crins do not pump water this energetically continuously, but only every now and then.

How about texture control? Here is a test render with a simple texture that allows me to see how the texture responds to the deformations. It worked as intended, so that's good. The deformation is simple and the background is not animated at all, but this is just a test render, after all.

And here is another test, this time with a more natural texture. It looks a bit like an octopus skin, which I like.

Work on the 'Great Cloakfish Designer' progresses nicely. But it will take quite time to get it ready, and only then can I start producing animations, even at a small size that I hope Fiona can work with. We hope to keep you informed of the progress on this blog, and possibly also on Fiona's blog.

Mr Masato's CGI creatures

Well before I cut down on blogging altogether, I had stopped writing about other people's projects regarding life on other planets. I did so more often when I first started blogging in April 2008, but then it was difficult to find anything about speculative biology. The 'speculative evolution' website that now caters for such needs probably started at more or less the same time (it says that I became its 42nd member on July 21, 2008). But in the following years the field grew, so I thought everyone would be able to find interesting work for themselves.

I will make an exception now, as I miss blogging. The main reason I chose to present the work of Mr Masato here is that it seems to have gone unnoticed, perhaps because it is shown on a Japanese website only, as far as I know.

His work can be found here. Oddly, that page will not take you to his speculative biology images; that is found here, or, without further clicking, here. You will find 30 images there, showing a love of strong colours, a fondness of cuteness that may be particularly Japanese, and a wide variety of forms, some odd, some less so. Mr Masato told me that there is no underlying story and that the images may well be from different planets.   

Speculative biology of the 'alien world' type is not his major interest. That is dinosaur work, as the other pages on his site show (I liked the page on Gallery 4 where he places CGI dinosaurs in Japanese street scenes). Mr Masata is one those artists who rely heavily on computer-generated images to produce his art. That approach has many advantages, such as that it is easy to take another view of a scene from a different angle, or change the lighting, etc. Once all such decisions are made, you set the programme to 'render', have some coffee, and there's the image. For some of the best work done along such lines, I recommend the book 'Dinosaur Art' (there will be a second volume too). But it is very difficult to get photorealistic CGI work to look convincing, oddly enough. Often there is something unnatural or even sterile about the placing of plants; the surface of water looks like it is made of jelly or of glass, rocks look like sponges, etc. Among the few people who can really pull it off is Marc Boulay, whose work I discussed more than once in this blog (for instance here and here). I personally do use CGI techniques, but only as scaffolding for a painting. Here is an example.

Click to enlarge; copyright Masato Hattori

Anyway, on to Mr Masato's work. I picked out three paintings. The first one is this odd head sticking out above the surface of the water. Well, I assume it is a head and not the entire animal. The hair is well done, in particular for CGI work, and the image as a whole is nicely mysterious. Notice the lack of background. In essence it's just the beast, but that scarce approach works well here.

Click to enlarge; copyright Masato Hattori

These 'armoured marmots' are rather cute, with their spectacular headdress. In my own creatures I often reduce the extravagance of such elements after the first sketch, but having looked at these daring shapes I should probably do the opposite once in a while. The rocks are interesting here; I think I can identify the texture from Vue Infinite that was used to make them. 

Click to enlarge; copyright Masato Hattori

I like this one because it is so full. It can be chore filling up a scene in a programme such as Vue Infinite, even though it has an 'ecosystem' features to help with that. There variety of plants helps top create a convincing scene. The tetrapod has very interesting rainbow colours, suggesting iridescence. The young animal again adds a cute element to the scene. The tusks worry me a bit: they look very slender, so they could break easily. With such a long neck the animal would have little need for them. The animal approaching the tetrapod seems to behave like a crocodile, slowly making its way towards its potential prey. The bony head with all those bumps reminded me of an uintathere. The best feature of this image are the wildly coloured blue flying thingies. Are they just there by coincidence, or do they have some relation with the 'uintacroc'? I like images that tell a story.
 

Painting 'Arrival at Furaha' I

I will try something new: I will document how I produce a painting, meant for The Book, as it develops. I always said I would not show new paintings, as that would probably ruin the chances of ever getting the book published. I decided to make an exception: the painting I have in mind is not a major one showing an animal or plant, but a minor one showing the human side of affairs. As you will see, digital painting uses a variety of digital techniques to help find a good composition, get the perspective correct, etc. I am not alone in this: If you read books on digital painting techniques, you will find that professional illustrators do this all the time. 

I needed a minor painting for the two-page spread introducing the chapter on the Nu Phoenicis solar system and the planetology of Furaha. These chapter introductions show a minor painting and a quote, usually from Souren Nyoroge, whose book 'Furaha and Earth: similar in their differences' elevated him from one from one of The First, to Furaha's foremost historical hero (I may slip from real life comments on the painting to 'in universe' remarks, so pay attention).

The quote was about Nyoroge, the scientist, and Bruyningh, the agitator, looking at the planet after arriving there and realising that from that point on it was not just a planet, but their World. That point in time seemed a good theme for a painting and I already had a scene in mind, with the two of them looking at the planet from their spaceship, silhouetted against the blue sphere of the planet. Over 20 years ago I photographed friends of mine in the Vancouver aquarium, silhouetted against the blue waiter of a large tank with beluga whales, with vertical window frames separating the worlds on either side of the glass. I would like to show that photograph here, but have no idea where it is. No matter: a Google search for 'Vancouver aquarium silhouette' will show you that many people took very similar photographs. However, there are no vertical window frames in the Vancouver aquarium, so I must have added the notion that there were any there to my memories at some time. Memory is  malleable.anyway, the mental image, with frames, looked better than the true view without frames, so I  went with frames. The design is simple: two silhouetted people, window frames, and a planet.

Click to enlarge; copyright Gert van Dijk

I have always illustrated the sizes of Furahan animals by adding the silhouette of a human, and these humans do not just stand there, but usually do something (I have seen others take up the habit of having 'scale-humans' do something, which I like). I either draw these silhouettes by hand or base them on a photograph of someone posing, which is them modified as much as it needs to be. Above are two such recent silhouettes. One was hand-drawn from the start and the other is based on a photograph; guess which is which...

For the 'arrival' painting I could have chosen the same route, but quite by chance I came across the free program 'MakeHuman' that looked like it could be useful. It starts with a generic 3D human of which the age, gender, height, weight etc. can be adapted easily. I made a slender character (Bruyningh) and a stockier one (Nyoroge). So far so good. But then I found that you cannot change postures in the program itself, but have to use Blender instead. Unfortunately, I cannot work with Blender; I find its interface incomprehensible (it is free so is certainly worth having a look). That's the end of MakeHuman for me, then. Luckily there were some example postures included, so I used those to export the two characters. These were not what I wanted, but I could easily redraw their anatomy and pose later; the 3D objects only serve as scaffolding for the drawing anyway.

Click to enlarge

The next job was to import these persons into Vue Infinite and to construct a spaceship. Luckily, all I needed of that spaceship was a floor and window frames. I wanted very large windows to give a luxurious feeling and allow the planet to be shown as a large object. I used 'cubes' to built the frames, imported the characters, hung up a big blue sphere and added some lighting. After that, I moved the 'camera' around to play with the composition. Above you see a view of the Vue programme showing the characters on their tiny section of spaceship.

Click to enlarge; copyright Gert van Dijk

And here are a few images of the results of this early stage. I decided to go along with something like the third one. At this point, I haven't started to paint yet, and I will keep that for the next instalment. But there are quite a few things to think about:

• I have to change the blue sphere into a proper Furaha model (I already have one). I will have to work out where the 'terminator', the line dividing night and day on a planet, should run. It has to look attractive but also has to be correct. This also includes working out how wide the blurred part of the terminator should look. The mathematics of calculating that should be easy, but I will check astronomical sources anyway.
• The window frames look fairly boring; perhaps I should change their shape
• The humans should get clothing; what does one wear during protracted space travel? Is it hot on a spaceship?

There are other implications: the image tells a lot about the Furaha universe. If people stand on a floor in a spaceship, they either have shoes that stick to the floor, or they have artificial gravity. I'll go with the last choice. So do almost all science fiction movies, so I doubt many people will even notice. 
  I already had a concept in mind of how people get around on Furaha: they use large lumbering vehicles that float in the air much in the same way that bricks don't (yes, Douglas Adams said that). They use a gravity-repulsing mechanism as a reverse zeppelin. A true zeppelin uses a great volume with very little mass to lift a few kg of mass; well, the repulsor zeppelin also lifts just a few kg, but using a great mass. Don't ask for blueprints. Not yet, anyway. This 'Leyden Mass Repulsor Net' (TM) works for spaceships too. Quite well, in fact, as its efficacy increases more than linearly with its own mass (I just made that up). Basically, you wrap the Repulsor Net (TM) around some mass, such as rocks, lots of water or a concrete-filled submarine, apply energy to the net and there you are.
  So all this explains why there is artificial gravity on the spaceship, why spaceship designers do not care about saving weight (the opposite, in fact), and in turn it explains why they can have large windows.

The Return of the Common Cloakfish

From time to time I find that my self-imposed restriction on not doing any Furaha work except working on The Book begins to chafe. I know that animations cannot feature in a book, but they are fun if very time consuming, and that holds for blogging too. So I gave myself a short vacation from painting and went back to an old favourite: cloakfish. The type of cloakfish shown in this blog previously as well as in this particular post is by now a primitive one. More evolved cloakfish have shown a considerable adaptive radiation: bodies were squeezed, cloaks either merged with the body or were stretched, etc., etc. There are now 'short sleeved' cloakfish as well as 'long sleeved cloakfish'.  The protocloakfish I will show in this post is a long sleeved one: the cloaks are considerably longer than they are wide.

The novel feature I wished to explore had to do with cloak movement. Until now, the cloaks moved with waves undulating backwards over the fin, pushing the animal forward. If you look closely at squid and cuttlefish, Earth's own indigenous aliens, you can at times observe that there seem to be several waves travelling over their fins at the same time: let's call them major waves and minor ones, and each set seems to be controlled independently. Here is a YouTube video showing squid movement: most of the time you see just one type of wave, but at times the pattern changes. I would not be surprised to learn that fin control in cephalopods is neurologically quite complex. I really must look up what I can find about that in my books on cephalopods (yes, I have more than one book on cephalopods: every self-respecting geek with an interest in speculative biology should devote part of a book shelf to cephalopods).

To start with, here is a simple animation showing just one wave pattern; let's call these the major waves. The waves are fairly large, meaning their amplitude is large and so is their length: they take up a sizeable portion of the cloak. The gait of the four cloaks is the 'opposite' pattern, in which the waves of neighbouring cloaks approach one another. The red ball is there only as a reminder where the 0,0,0 point is in this virtual 3D space.

The next phase, above, is of course to show the minor waves: there are more of them and they travel faster along the cloak. Mind you, I have not considered the effects of interacting waves on propulsion much yet; my first suspicion is that they can augment one another, but if they can do that, they can probably also hinder one another.  Hm. This will require thought.

Anyway, programming and visualising all this makes it difficult to think of everything at once, so first let's see what the combination looks like. Here it is. I like it; it is complex and looks organic and fairly odd. The movement reminds me of that of nudibranchs (if 'nudibranchs' mean nothing to you, just use that word to search for images in Google. You may find that you have to make room next on your book shelf next to the cephalopod section; nudibranchs look delightfully alien too.)

   
Very well, let's now assemble a whole cloakfish with this new swimming pattern. The body assemby is modelled very roughly here, without any details at all. As you can see, I wondered whether cloakfish might be able to change colour? I do not see why not, so here is my first attempt ever of depicting a Furahan animal changing colour. For the technically minded, the colour changes require  two steps: first I wrote a simple Matlab program to interpolate colours between two images, resulting in a new set of images showing intermediate changes. Second, I wrote a python script to get Vue Infinite, the programme I use to render the image, to load a different image to use as texture for each frame. In this case the changes in colour are not that big, but you can probably envisage cloakfish changing colours in much more radical fashion.

Here is the colour change again, first in close-up, and then in the form of a short scene of a common cloakfish making its way over a reef. Those who are very observant will see that the alignment of the body with the cloak-and-dagger assembly differs between the two animations. The reason for that is simply that I forgot to rotate the body around its longitudinal axis by 45 degrees. The reef scene shows the correct position of the body.

Anyway, clearly and obviously, animations have their own attraction and advantages, such as showing colour changes. How can I ever show a cloakfish changing colour on a painting?    

Unveiling cloakfishes' cloaked filters

I stopped blogging, so what is this post doing here?

Well, I never said I would stop altogether, and I would return if there was something of special interest to report. Yesterday, I received my advance copy of  'Demain, les animaux du futur' from the authors, Marc Boulay and Jean-Sébastien Steyer. I am quite impressed and will return to write about it, in a week or so. Writing the present post is to get me in the mood again.

A main reason to reduce blogging was to spend more time on producing The Book, and that worked quite well: without blogging, I manage to produce one two-page spread every month, meaning one full painting, accompanying text, scale drawings and usually a minor illustration. At 24 pages a year there is definite progress (and I intend to increase the output). Sadly, Fishes I, II and III together only get one spread, while terrestrial hexapods get many. To illustrate the mechanics of some groups, I have stumbled on a three-spread theme: one spread for explanation, one to show diversity, and one showing a single species in a full painting. Groups that get this treatment are spidrids (half finished), rusps (all done), tetropters (not yet) and cloakfish: half done.

Click to enlarge; copyright Gert van Dijk

The early beginnings of cloakfish are shown here, and the latest instalment of their physique was posted here. Like it or not, that particular form, shown above, has now been scrapped. As you can see I played with putting the mouth in the cone forming the 'snout' of the animal. Well, not anymore. While sketching I drew a cloakfish cut in two and that gave me the idea of making a 'cutaway' version to explain how it works. Unfortunately, that meant that I could use very little 'handwavium'. Without a cutaway drawing I could just write something like this: (imagine an Attenborough-style voice-over) "Hidden from view by the animal's cylindrical body wall, its food rakes, next to the gills, steadily filter the nutritious plankton so abundant in these waters." How they look is left to the imagination.

With filters unhidden, the problem presented itself that I never really understood how filter feeding works, which is no wonder as I never looked it up. Many animals use it, from sharks and rays to bony fish and whales. So it works, but consider a whale shark or a basking shark as a gigantic sieve sweeping through the ocean. After a while, the filter will have sieved lots of food particles, now stuck against the sieve. The animal will have to scrape the food from it, not only to swallow it, but also to prevent the sieve becoming clogged. Remember that the gills are there as well, and you do not want to ruin respiration, not even for feeding. What bothered me is that whales might use their tongues to scrape clean their baleens, or so I supposed, but I was not aware of scrapers inside a whale shark's mouth.

Click to enlarge; Source: Brainerd, Nature 2001; 412: 387-388

Well, reading a few papers later I found out about something called 'cross flow filtration'. Naively, I had imagined the filter as a sieve at a right angle to the flow of water, allowing water to pass while particles get stuck. That's not how all filters work, though. The image above explains the process nicely. In 'cross flow filtration', the surface of the filter is parallel to the flow of water. Behind the filter there is a low pressure area, so water flows there. Apparently, particles move on parallel to the water, staying on one side of the filter, where they are  concentrated more and more. The papers then mention things like 'near the oesophagus', suggesting that the animal then merely has to swallow the concentrated particles and there you are. If you want to read more, I found a site where you can obtain a Nature paper for free here. Mind you, the fact that this was worthy of publishing in Nature in 2001 means that this is still all fairly new. The papers are somewhat vague on why the concentrated particles bunch up in a cul de sac waiting for the oesophagus to gulp them up, but I will accept this leap of faith; it cannot be easy to do an oesophagoscopy on a freely swimming whale shark.

So I sketched some more, filling in the inside of cloakfish contours, giving it a cross flow filter with a cul the sac leading to the oesophagus. Actually, since we are talking about a tetraradiate animal, there are four filters and four oesophagi leading to one stomach. I paint but am not a technical artist, so I needed some help with the perspective and also with visualising the insides of the cloakfish. I used Vue Infinite to provide me with as many perspectively correct views of the animal's inside as I wanted to help draw the cutaway.

Click to enlarge; copyright Gert van Dijk

What you see above are some aids in doing so. The holes help visualise the flow of water (but I must add that the gill design was changed afterwards). The painting, based on this design, is nearly finished, but I will not show it: there should be new material in The Book. My first look at the 'Demain' book showed a very large amount of previously unpublished animals, and that strengthened my resolve to keep much hidden. I must say that writing this post did remind me why I did it for a long time: it is fun; but time is short...                          

The wrong farf (Tetropters VI)

I made a few animations especially for the Loncon3 convention, some of them concerning tetrop
ters (see here for the previous tetropter post). The reason was that I wanted show some of the 'flight platforms' that tetropters could conceivable evolve into. So far, there are the 'standard, 'rowing', 'helicopter' and 'farf' modes.

Click to enlarge; copyright Gert van Dijk

These modes all have to do with the relative amount of movement in all the four ways a tetropter wing can move. The image above shows the idea: there is a general tetropter body, characterised by its vertical position, four jointed legs at the bottom and a head with sensors at the top (there is a head with smaller eyes and a mouth at the bottom end of the body, not visible here). The red, blue and green axes run through the attachment point of one wing and concern the movement of that wing. There are similar axes systems for the other wings, but these are not shown (the wings are, though, just). The arrows indicate the direction of rotation of each axes. A to and fro movement around the blue axis will result in a clockwise and anticlockwise movement. If you combine that with an up-and down movement around the red axis you get interesting patterns: the wing could describe a circle, but the most common pattern is a horizontal figure of eight. The wing moves clockwise and down, then at the end moves up quickly, so it can move down again while moving anticlockwise. That just leaves the green axis, which rotates the wing around its own longitudinal axis, allowing it to achieve the proper 'angle of attack'.

I said there are four ways to move a tetropter wing, and the fourth is not a rotation around an axis as are the first three, but warping the plane of the wing. Well, if you followed that an can envisage it, top of the class. Its more or less what you need to describe the movement of the wings of animals with hovering flight, so we are on common ground here.

I will probably come back to the other tetopter flight modes later, but let's talk about the farf mode. A farf is short for farfalla, the name the Furahan citizen-scientists gave to tetropters with a very long wing base. In fact, the image above has just such a wing membrane: you can see that the membrane lies against the vertical blue axis over its entire length. Actually, the wing membrane shown here would not be an actual one. It is just a rectangular placeholder, but is does show the principle of the thing nicely. This arrangement means that movement around the green axis cannot take place, and to get a good angle of attack the wing will have to warp considerably. If you think this scheme reminds you of a butterfly, you are right: butterflies also have wings with a broad long wing base. In fact, 'farfalla' is Italian for butterfly.

So here is an animation of a farf, made for this post, showing the placeholder wings. Not too bad, is it?

And this is the one I showed at Loncon3, with colours etc. Just about the day before I showed it, it dawned on me that I probably made a mistake in warping the wings. When the wings clap together, they have to be more or less flat, and then they should peel apart, first at the top, and then downwards towards the bottom. Well, that bit worked, but for some reasons I had also warped the wings in such a way that the distal end of the wings –that is the bit farthest away from the body- leans into the movement, so it moves before the part near the body. But the wings would encounter resistance from the air, and so the tip of the wings should probably lag behind the proximal part instead of leading it.

I do not think anyone noticed, but I also did not give the audience a long time to think about it. I will have to do another animation with the opposite effect, to see whether that looks better. But there's no time for that yet... Meanwhile, I hope you still enjoy the 'wrong farf', warped as it is.

A better mantacloak animation

I'm not saying I will definitely resume blogging, but I may...

I had prepared some nice new animations for the Loncon3 speculative biology event, and decided to add a few scenes to make a nice animation. The thing is, rendering each image takes so long, that it becomes very difficult to tweak the result: whenever you think something like 'the cloakfish should come in here and not there', or 'the light should shine on it from there and not here', you have to reprogram a scene all over again, and then have to wait while the computer renders the 500 or so images for each short scene. So I do not think I will start a career animating Furahan wildlife documentaries. Just the odd scene every year or so. Mind you, I have some three new tetropter scenes as well. But I will wait a bit with those. I am thinking about the ultimate post on toes: 'why large running animals really need toes or toe-analogues so you should not give them elephantine feet'.

But first: A cloakfish accompanied by Debussy. This is NOT the best way to look at the video, as it is a 800x450 video. I will upload it on Youtube as well: http://youtu.be/IXaR5VxrMSA

More cloak and dagger stuff: cloakfish IV

Cloakfish have been discussed here previously; for the latest instalment, go here. Before I go on, I wonder how to call them; the plural of 'fish' is still 'fish' when you are talking about the same species, but as far as I know 'fishes' is correct when dealing with more than one species. So should I write sentences like 'Clown cloakfish are founds in their thousands under floatreefs' and 'The many cloakfishes of all shapes and sizes in the peri-Archipelago seas'?

Anyway, cloakfishes (!) were developed as animations before I painted them. So far, they were animated using MS-DOS, believe it or not, but the result was a bit two-dimensional. I later used Matlab too, but only as a painting aid, not to produce animations. Their bodies were very simplistic and the cloaks themselves were just sheets, without any thickness to them. But when I saw large cloakfishes in my mind's eye, they floated majestically into view, with cloaks as substantial as those of a manta ray. In fact, the one I will show now is a 'shortsleeved cloakfish' so it does look a lot like a ray, but with four-sided radial symmetry, obviously. So how could I realise such a vision?

Click to enlarge; copyright Gert van Dijk

Well, with difficulty... The overall strategy consists of several steps: the firsts relies on Matlab to design the overall shape of a cloak, as shown above. The various curves are combined to form the outline of the cloak as well as of the part of the body -the dagger-  it is attached to.

Click to enlarge; copyright Gert van Dijk

Then, flesh out the form by creating two surfaces for each cloak so it smooths into the dagger. What you see above are two such half cloaks, together making up one cloak. If you were to stick four such ensembles together you would have a full cloak and dagger assembly.

Of course, there is movement to think of, and the shape of the cloak has to be changed over its movement cycle. I divided the cycle into 200 steps to have some temporal resolution. For each stage of the movement there are eight half cloaks, so we are now at 1600 files. All these shapes are written to store as 3D obj files, again, using Matlab.

Click to enlarge; copyright Gert van Dijk

Meanwhile, design a head in a suitable program such as Sculptris. There you are; it is not very detailed, but more details would probably not be visible anyway. Also create an underwater landscape in Vue Infinite with a simple animation to allow the cloakfish to glide through the water. Open the programming language Python and write a script for Vue Infinite; from within Vue, use the Python script to load the eight appropriate half cloaks for each frame, the head too, assign textures, transport the lot to the correct positions, render an image and store it. At a reasonable resolution of 640x360 that will take about 30 hours.

Copyright Gert van Dijk

All that remains then is to create a film, perhaps add sounds, etc. What you see above is a trial version in which the cloakfish is just white. I rather like the movement. For a better view, visit Loncon3, where I intend to show a good version... 


PS 1: this is post #200...
PS 2: I am considering returning to blogging regularly after Loncon3.


(PS 3: this is to stop a particular site from copying my blog: 7InDB4PgQaCddePKQEqA )

Influence of the rostrum linkage system on forage volume in Brontorusps (Brontocrambis brucus)

A Christmas Special!

Ahead of the normal schedule, and with dinosaurs, rusps and biomechanics!

Click to enlarge; copyright Gert van Dijk

The title of this post sounds like that of a proper scientific paper, doesn't it? Something out of the 'Journal of Astrobiological Biomechanics', I guess. It's time to look at rusps again. My big rusp painting is finished, and as it is meant as a double-page spread, it is large: 7200 by 2700 pixels. A spoiler is shown above showing a fragment of a rusp in the background of the painting. The fragment has been halved in size and its area represents just 2% of that of the entire painting. The painting is based on earlier sketches. For more on rusps, either visit the main Furaha site or look at these posts: sketches, anatomy, predation, concept paintings, etc.  

The evolution of new Furahan animals gets more complicated with time. In the beginning I just sketched a pleasing shape and started painting right away. Now, I worry more whether the animal makes evolutionary, mechanical and ecological sense. Well, up to a point; this is science fiction and supposed to be fun, after all. 

Here are some of the steps in rusp 'ontology': they started with some quick sketches, and then the slow evolution began: successive legs were offset medially and laterally to avoid legs bumping into one another, followed by an arrangement for their skeleton. Their fore and aft whips are long and held horizontally rather like the tails and necks of sauropods, and hence have a similar system of internal trusses as compressive elements at the bottom and ligaments at the top to withstand tensile stress. The whip is held up passively by these forces, so avoiding the high cost of doing that with muscle force only. The last stage involved refining the head of the rusp, and in particular its snout, or 'rostrum'. In an earlier post this rusp species was called Mammoth Rusp / Megacrambis, but now it is the Brontorusp / Brontocrambis; yes, that means 'Thunder Caterpillar'!  The Mammoth Rusp still had some intricate limbs functioning as additional feeding aids under its snout. I was not too certain of that arrangement, and my doubts were confirmed by comments on that post. So the Brontorusp no longer has these additional mouth parts. The thing is, now we have a massive animal with a large head. How does it feed itself?

The mouth of the rusp is in its head, which seems obvious but in speculative biology not many things are obvious. Also note that rusps are large herbivores: they need a lot of food and spend much of their time eating. Moving about is costly, so it would be best if they moved the least possible amount to get their food, which does not sound as if there is much room to save energy. Let's tackle that by considering the problem of getting an animal's mouth on vegetation; there appear to be four solutions to do so; rusps use the fourth, but we'll come to that. The first solution, always necessary as vegetation will not come to you, involves walking to the food source.

Click to enlarge; copyright Klein et al; Biology of the sauropod dinosaurs. Indiana University Press 2011

But once an animal arrives at its 'foraging station' a nice way to save energy is to keep most of the body motionless and to have a long neck allowing the head and mouth to move about independently of the gut. For very large animals, needing to feed all day, it pays to divide their anatomy in mouth and guts; the rest is just 'other bits'. Sauropod dinosaurs used that method, and the image above is from a study on how far sauropod mouths could reach, depending on neck length and leg length. The idea is that the neck can move in a horizontal plane 90 degrees to the right and the left, and in a vertical plane straight up and down. If the animal is lying on the ground the volume of space that it can reach is one quarter of a sphere. If the base of the neck is higher up, when the animal is standing, the volume increases. The authors assume that the bottom part of the volume then is cylindrical whereas I would assume that to be spherical as well, but never mind.

Click to enlarge; copyright Gert van Dijk

Swans and geese have very flexible necks and can probably reach every point within that envelope, but if an animal has a neck less flexible than a swan's, only part of the volume is accessible to the mouth. If this is the first time you realised that geese and sauropods might have long necks for a similar reason, good!

The image above shows an adapted 'forage volume' for a sauropod: the outer red sphere is the outer limit of where it can reach, and the inner blue sphere represents the inner limit, assuming that the neck is too stiff for the animal to reach a point closer to its body. The human ('Marlene') is just there to keep the sauropod in its proper place. 

The third solution to get the mouth near food is to use an appendage to shovel food towards the mouth. The best example I can think of is the elephant's trunk, which greatly increases the elephant's reach. The erstwhile rusp mouth limbs were short and not at all good as harvester limbs, and I did not wish to elongate them tenfold; they are gone. I also did not wish to turn the whip into a grasping organ. Rusp whips are not built for that, although in a pickle they can probably be used to knock a branch off a tree. Instead, rusps use a fourth system which is really just a combination of the last two: they carry their mouths towards the food without moving the rest of the head. The 'mouth extender' is extensible and based on a mechanical linkage system. In itself this is certainly not a new idea: Earth fish have such systems in abundance.

Click to enlarge; copyright Gert van Dijk

This image shows a schematic view of the rusp rostrum. Start with the red shape in the foreground: it consists of two V-shapes starting from a vertical axis. All places where elements meet are in fact joints. The pink axis shows that the whole ensemble can rotate, but it can do other things as well: if the two Vs rotate towards one another, the whole shape will become longer and narrower. At its right end, the shape ends in two points on a horizontal line. Now copy the shape, rotate it by 90 degrees, and you get the blue shape in the foreground. The two points where the red shape ends act as connection points for the blue shape. Once connected, some movements from the red shape are connected to the blue one, but not all, and that makes the rusp rostrum quite versatile. In the back you see how the rostrum is formed by stringing red and blue shapes together. In reality the trusses are not formed by straight bones, but by curved ones, so the section of the rostrum is circular rather than rhombic. The cylinder on the right attempts to show the outlines of the bones on a cylinder.

Click to enlarge; copyright Gert van Dijk

And this image shows an as yet unmentioned aspect of movement: if the two starting points are brought closer together, this changes the section of the rostrum as well as its length. The right one is extended, the middle one shortened, and the right one is in neutral position. I expect rusp rostra (yes, that's the plural) to be able to double in length.

Click to enlarge; copyright Gert van Dijk

But we need more flexibility, and that is achieved by rotating the shapes and using the angle between the Vs for additional control. The stylised skeleton in the back shows what can be achieved. So there we are: an extensible and steerable system to get rusp mouths where they would otherwise not reach.

Click to enlarge; copyright Gert van Dijk

Here are two views of an adapted Sculptris model of a rusp head. I take it you will recognise the system of trusses under its hide.

Click to enlarge; copyright Gert van Dijk

And finally, a schematic rusp foraging volume, rather like that of the sauropod (the whip of this model is truncated). Note that the rusp can access a larger portion of the outer foraging volume than the sauropod. The volume itself is smaller though, as rusps are smaller than sauropods, and their rostra extend their reach, bot nearly as much as the sauropod's neck does. Marlene is standing in the forage volume, something I would definitely NOT recommend! In practice, rusps are ground feeders, not bothering about high branches. Have I told you about the ecology of the spotted plains where they live, where post of forests alternate with plains and how rusp feeding habits are to blame for that? No? Oh well, that is another story.  

Red leaves, swaying in an alien breeze...

Readers who have followed my series of posts on alien plants and photosynthesis (here, here and here) will know that I have no objection against plants on other world not being green, so that is why there is  'red' in the title of this post. But this post will not be about photosynthesis, as I think that theme has been dealt with sufficiently. The next theme on plants will probably be about biomechanics, but I have not started that one yet.

This post is about portraying alien plants. Obviously it is possible to do a painting, and that is fine, but it is also a lot of work. Can't computers do part of the work? There are not that many software choices available to populate a landscape with alien plants. The one I have been using over the years is Vue by E-on software. Vue is difficult to handle, in part because there are many options that are not all well-explained in the manual, but also because the software can be very unforgiving depending the hardware you are using. In other words, it may crash. It is the kind of programme that you can easily develop a love/hate relationship with.

It has an ecosystem feature, in which you choose plants or objects, adjust their rations and relative sizes, and when you then press 'populate' the programme does just that. It can even take matters such as height or slope of a landscape into account, placing some species there and others not. The problem in designing alien forests was that Vue's innate plant designer was inadequate: it let you design variations of Earth plants, but made it impossible to design something more interesting from scratch. For that I used XFrog 3.5, a programme that allows the user to come up with intricate new shapes. The XFrog plants could be imported into Vue, and did allow worlds to be populated with alien plants. Some examples of my earlier efforts are here for Epona and here and here for Furahan swamps.

However, there was one disadvantage: Vue's own plants could sway in an imaginary wind, but the imported XFrog plants were static objects. For static images that is obviously not a problem, but for animations a forest in which no leaf moves is just odd. I have stopped doing Vue animations for that reason.

Recently, E-on introduced a new programme: The Plant Factory (TPF), which does let the user design plants from scratch, with the promise of having the result sway the wind. That was attractive, so I decided to try it, even though the user forum made it clear that this is a typical E-on product: it can do amazing things but often in a roundabout or unexpected manner, and sometimes it simply does not deliver. TPF has no manual whatsoever, so anyone wishing to use it should treat it as a voyage of exploration rather than as a productivity tool. There is a 'personal learning' version, so everyone can test it without spending (rather a lot of) money on it.

Click to enlarge; copyright Gert van Dijk

 I first tried whether I could make it design oddly shaped plants, and here is one of first attempts. I tried to obtain a results resembling an earlier XFrog design, and that went reasonably well, as you can see above. As you can see, this tree has its major branches growing from a central trunk as do Earth trees. Its branches curve through the air to reach the ground, where they may take root, providing water and nourishment or simply offer structural support. The proportions are not right yet, it is a start.

Click to enlarge; copyright Gert van Dijk

The image above shows a hillside populated with two species of simple plants, home made in TPF. The scene was intended to experiment with wind animation. The first result was disappointing in that there was hardly any movement. There are lots of sliders controlling wind, which I had left at their original settings. Apparently those are meant for an unnaturally calm day. Very well, let's turn the wind setting up to 100%. That did not do too much either. I remembered an earlier surprise in Vue, dealing with lens blurring; there too a setting of 100% was almost negligible; someone at a forum told me to not to treat 100% as a limit, and so here too I set wind animation to 500%, and now at least the leaves move. Apparently this is more or less a dimensionless unit; just one of those odd Vue quirks.

  

And here is the result; better, I think! It's not a storm yet, but at least there is movement! The quality of videos on blogger is not very good, so it can look a lot better. Meanwhile, there is still a very large number of options to discover or, given the lack of a manual, to blunder into, so do not expect a to see a marblebill brachiating through a Furahan forest. Not quite yet, anyway.

Spidrids and rusps: works in progress

The main Furaha site hasn't seen any significant change for quite some time now, which makes me feel a bit irresponsible. I have devoted the time I spend on this project wholly on the blog and on new paintings. As for the site,  I will get around to a complete 'redecoration' one of these days, and the blog is what you are reading right now, so there.

I am keeping the new paintings for the book but can show you bits of works in progress now and then, both of paintings and of blog material. In this post I will show progress on two themes, not that odd as I usually work on several themes at once (a major interest at present is working out which aspects of plants can be tweaked on other worlds, and what the results would look like; that is progressing nicely).

Copyright Gert van Dijk

I have discussed spidrids here several times, the last time here. That post showed them walking on uneven terrain in a variety of gaits. Those animations, done in Matlab showed how an animal with radial symmetry changed direction without turning. Although the animations showed that well, a proper 3D animation would be better. I am not aiming to achieve the quality of Avatar or Walking with Dinosaurs, but getting to a point in that general direction would be nice. The challenge then was to translate sets of coordinates of one system (matlab) into rotation and translation values for objects in a completely different format (Vue), and then controlling Vue to make an animation one frame at a time (Python). I won't bother you with the details. As you can see above, I am now at the stage where I can control the legs and have them end up on the right orientation and position. It really looks much better at a larger size, but blogger does not allow that. The low light was chosen so I could see whether the feet end up on the correct spots of the surface: their shadows just touch them, so that works! But when the innermost segment moves beyond the vertical, that segment flips around, so my rotation subroutine isn't quite right yet. I'll solve it. Meanwhile, it's starting to look real, isn't it? Now just imagine a body in between, texture on the ground, plants and shrubs with leaves swaying in the breeze, the sound of spidrid legs on the floor, and the occasional 'chikking' of the spidrid itself. I can see it already; perhaps imagination is better than animation...

Click to enlarge; copyright Gert van Dijk

Rusps! After my last encounter with them I thought some more about a possible painting. I decided it would look good as a double page spread, occupying the top of both pages. That results in a very wide format, just the thing for an animal that is itself long and horizontal. I decided to 'stagger' successive legs: segment x has the legs placed a bit to the inside, and segment x+1 has the placed to the outside, x+2 to the inside again, etc. In that way the stride might be long without the animal knocking its legs together. As there are so many legs, each one can be skinny. So I took the 3D model of a segment I did earlier, strung them together and starting playing in Vue with positions and curves. But I also needed a head, so I sculpted one roughly in Sculptris. I do not need a detailed sculpt as the sculpt is only a simple aid to produce the painting, not an end in itself. (Then again, if I did that, I could perhaps sell you models of spidrids and rusps). That is what you see above.

Click to enlarge; copyright Gert van Dijk

Here is another view of the rusp head. You cannot see the inner design of the snout, but the story is as follows.This particular rusp species, Megacrambis brucus, is very large and has an accordingly large head. It always pays to conserve energy, so moving that massive head or even the entire body to eat one bite is wasteful. It is better to stick a small head on a long neck (sauropods) or extend the reach in another way (arms, trunks, hooks). Inside the rusps' snout, technically a  'rostrum', there are rings connected to one anther at right angles to allow pointing the rostrum in all directions. Then there is one of those intriguing linkage systems that fish in our world excel at. Putting that in action extends the reach of the rostrum two- to threefold. Finally, at the end there are some grasping mouthparts. I put some more conventional mouth parts underneath; they are probably part of the overall rusp design.

Click to enlarge; copyright Gert van Dijk

Anyway, I put all he 3D parts together in Vue and played some more, seen at the top. Below you see  a quick over painting of the result. I was aiming for an overall diagonal effect in the composition, of which the shadow falling over the rusps's body is a part. I am not certain whether I will keep it though. I will keep the strong light against the dark clouds, as it helps to highlight the front whip. Megacrambis' English name will be 'Mammoth rusp', but I am not certain yet. Furaha was first discovered by Swahili speakers, so some of their names survived. I am also considering 'Mdudu Mzee' , roughly translated as 'respected elderly bug'. Any preferences?