Archive for xsi
Since LK Fabric is out I dug up one of the early test scenes we used on Nike “Evolution” at Royale in which we developed some of the techniques we used to get various looks. This setup is very basic but covers some of the key tricks for getting a natural result and was used as a starting point for a number of shots.
I have replaced the original many-versions-old compounds with ones from Leonard’s public release, and have also left in a few “helper” compounds I built which weren’t part of his official release. I then removed everything superfulous to the basic effect and commented the resulting ICE tree throughout. Any typos or misspellings are entirely my fault. :D
The actual setup is very simple.
This scene demonstrates:
- A basic setup of a single evolving swatch of fabric, with the most basic pattern and the modifiers we used most often.
- Using the “slide profile over U/V” compound and other techniques to shape the leading edge of fabric growth.
- Using the “offset” core parameter to make the leading strands animate and form a shape for the thread tips.
- Using a second ICE “post” effect to add per-strand variance and “frizz” effects.
The early tests like this were pretty chaotic, we knew the system did a good job of creating a “perfect” weave so we were pushing in the other direction and adding ways to create chaos and randomness.
Ironically despite the first briefs being focused on “organic” and “evolving” concepts the client spent much of the latter half of the job dialing in a more out-of-box mechanical look… that’s the way it goes sometimes. But this means there is a lot of capability which hasn’t been seen yet. I’d love to see some people use some of the per-strand and per-thread modifiers, and the capability to create patterns beyond the basic “canvas,” to create a more organic, aggressive look.
Here’s the file (Softimage 2013 scene file, ~0.6mb): LKFabric_AMexample1
Here’s a scene file and a couple of compounds which compute a simple noise function and then create a reticulated “push” from it. It’s meant to demonstrate how a simple spatial noise can be layered on itself to create a fractal, visually pleasing result, as well as give a little insight into how functions like perlin, worley, turbulence etc can be similarly layered to create a huge variety of natural looking patterns.
Scene file and compounds (softimage 2013): example_ICE_reticulation
Softimage, Arnold, ICE and LKfabric, intensive small-team project @ Studio Royale, I think this video is meant to play in the Nike stores inside of a sculpture/model of the loom. If anyone sees it in one of the store sculptures, send me a pic, it sounds cool. :)
Two of 3 spots. “Evolution” was a small team, 3 weeks, lighting and effects with Softimage and Arnold.
I love small but intense projects like this.
“Run” was primarily Maya/Vray with a touch of ICE. The studio (Royale) is only 6 years old but advancing fast, and it’s been a real pleasure working with them. For their first exploration of ICE, Royale invited in some familiar SI friends – Ciaran Moloney, Steven Caron, Leonard Kotch, Billy Morrison and yours truly doing a first gig start to finish as a CG sup (which with guys like this mostly involved saying “go for it.”)
Like the Psyop “Telstra” spot, this commercial essentially required us to create a system for knitting cloth from massive numbers of strands. Leonard Kotch wrote a system which performs many of the same tasks as the Psyop “Entwiner” tool, but he took a slightly different direction, it was fascinating to compare how the two diverged. The progressive animation required for these two shots resulted in a pretty flexible and broad system, which we are currently using for the last of the three spots, which will wrap in production soon.
Royale has been an enthusiastic and fun group to work with and it’s been great getting to show a studio as strong as they are in design some of the possibilities ICE can bring to jobs like this. Expect to see some version of Leonard’s “LKFabric” system gifted to the community before long – very cool Royale, thanks! (They also throw good parties, their 6′th birthday celebration was impressive and… unusual.)
A user on si-community asked how to “move” the deformation in the earlier whirlpool example. Doing so involves a couple of matrix transformations – you basically force the points of the geometry to the global origin where you perform your deformation and them move them back to the local space they were in.
It’s a simple operation that I haven’t really figured out how to illustrate in a simple and intuitive manner yet… about the best I could do was to revise the scene so people can compare a “before” and “after”. The first scene is a working scene, it’s where I was assembling the basic deformation, it’s all relative to the global origin. This new scene then goes through the steps of making the deformation “production ready.” I clean things up, make the deformation operate in the object’s space, and package it all up as compounds.
Here are the compounds and the revised scene (2013): example_whirlpoolDeformer2
There are a billion discussions of the Fibonacci sequence, phi, the golden section etc. So I’m going to let you browse the wonderful web and largely find out about it for yourself (try here), with only this brief summary…
The Fibonacci sequence is a series of numbers such that the last two numbers of the sequence added together result in the next: 0,1,1,2,3,5,8,13… ie: Fn = Fn-1 + Fn-2.
If you take the ratio between any two consecutive numbers in the fibonacci sequence, they increasingly converge towards a single value, 1.61538 (memorize it!) which is called the “Golden Number” or Phi: Φ
This ratio is found throughout nature, as well as classical art, mathematics etc. It crops up in an amazing number of places. A logarithmic spiral in which points of the spiral are Φ units apart after a quarter turn is called a “golden spiral”, for instance, and can be found in seashells, seed pods, flowers, pinecones and as I said before, lots and lots of websites. If you’ve had a certain amount of coffee, this video might be illuminating:
Other artists using ICE have put out tutorials and compounds relating to these spirals, browse around (hint I’m one of them.)
Recently as I fiddled around I came across an interesting point about these kinds of distributions that caught my attention: they are a very efficient way to pack particles evenly on a surface. This is an important point to an effects artist, because not only is a large part of this job mimicking nature, but distributing points efficiently on surfaces lets us maximize the number of non-overlapping particles we emit.
So, I built some compounds, first to calculate phi (or simply return it as a stored constant, depending on the accuracy needed.) Another to convert phi into angles in degrees and radians (the “golden angle”), and finally I took these and made an emitter. Hooray, it indeed did allow me to emit a sphere of particles packed efficiently, and even better since I didn’t have to use a “generate sample set” it allows millions of particles to be emitted much faster than simply emitting particles from spherical geometry, and without any resolution-dependance on the LOD of a polygonal sphere. And this “phi” distribution has a nice, natural look.
Here are the compounds, enjoy: ICE_phiDistribution
The simulation is “meh”, but it was a test. This scene wasn’t originally about particle clumping, either: that was just put in as a way for me to play with the idea but not really my original focus. I was using it as a testbed for a homebrew collision/bounce node, which functions, but in the end that part wasn’t anything particularly special or even sophisticated. The clumping part is more interesting in the long run.
Someone recently asked about clumping particles online, and I recalled that I had this scene on hand. So here it is, as built by yours truly while never intending it to be anything other than personal experimentation… with some comments put in after the fact.
The file (softimage2013 ~8mb): example_createParticleClusters
A discussion about Mudbox and Zbrush-style shading arose on the Softimage mailing list. Their signature look comes from “MatCap” shaders (originally known as lit-spheres.) It’s a popular way to achieve a custom lighting solution from a texture, in realtime, which is particularly useful when modeling – you can get a nice clay or sculpy “look” to geometry in realtime. It’s also useful for creating nonphotorealistic (NPR) looks in realtime, toon shading etc.
As mentioned in an earlier post, the grey-ball shader in mental ray can render litsphere textures, and a user suggested that in the high quality viewport you can get the desired result by plugging the metaSL node “Map_ball” into the environment channel. The problem with this is the result (on my machine, at least) appears in world space. A proper litsphere should be in view space.
But it called my attention to something important – almost all of the metaSL nodes used in Mental Mill are now accessible in the render tree and can be used similarly – meaning for most intents and purposes all softimage users now have Mental Mill. Which is awesome.
But we still needed a solution for matcap functionality in the high quality viewport. So I bit the bullet and wrote a metaSL shader which seems to do the trick. It can be used for both realtime performance in the high quality viewport as well as full renders in mental ray (and any other platform supporting metaSL.)
Update: Daniel Brassard kindly fixed some bugs, the new version is now available below. Thanks Daniel!
Here’s the shader (MetaSL ~2kb): litsphere_v1_1
More examples of the shader:
This scene shows how ICE can be used to display custom information about aspects of a scene. In this case, the cone of a spotlight is displayed, with an option to display a projection of the spotlight on the surface of geometry. A second example shows how the same setup can be used for a near and far attenuation display.
One great thing about ICE is how easy it is to re-use and re-task your “code.” In this example, it is simple to save the null containing the ICE operator as a model. Any time you need this display, import the model and give it your spotlight’s name, and you’re done. Or better, write a script which does this for you so all you have to do is pick the light. – AM
Here’s the file (softimage 2013, 276kb): ICEspotlightDisplay
Petr Zloty sent me a useful tip… when you place the ICE operator on an empty pointcloud rather than a null, the results display properly in any viewport. This is an important realization which is really good to know. In fact, the problem with ICE display attributes on nulls only appearing with wireframes is an annoyance which I’ve bumped against more than once. Thanks Petr!
Rob Chapman posted a cool whirlpool deformer to the “Resource Dump” on SI-Community here. Since I had been doing a lot with logarithmic spirals recently I decided to make one from scratch and compare the two. Here’s the result.
Instead of using Rob’s wave deformer, since it’s fun to share it out there’s a “ridged turbulence” compound in there. Here’s what it looks like when used as a deformer:
And here’s the file (softimage 2013 ~160kb): alt_whirlpool