Andy Moorer is a VFX artist and TD working in the film industry.

Archive for ICE

Jan
24

Example – Display Spotlight Data

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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

Update

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!

Thanks Petr for the tip and the screenshot!

Thanks Petr for the tip and the screenshot!

Categories : 3D Graphics, Examples
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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

Categories : 3D Graphics, Examples
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Jan
18

Example – Taper Deform

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Unlike most of the examples, I built this specifically to show how a deformer can be constructed with simple visual guides. So the good news is that it’s all nicely commented. This example shows the structure of a deformation, some tricks for making viewport guides, and the taper function itself (originally published by Alan Barr, it’s quite simple).

The down side is that I didn’t want to get into matrix transforms for the example, so this implementation is only on the object’s local Y axis. This limits it’s production value (not that there’s a great need for another taper deformer.) It’s an example, not a tool – adding in the transforms to make the taper axis arbitrary isn’t too difficult, but as I was making this I realized it was going to make the entire thing unreadable and that I was out of time – I have paying work I need to get to. ^_^ So here it is, as-is. Cheers – AM

File (softimage 2013 ~270kb): Example_TaperDeform

Update

Had a little time and I hated leaving this in a state that wasn’t that useful, so I added in the additional kinds of control I usually have in production compounds (in this case, mainly the optional ability to deform on an arbitrary axis as supplied by a control object like a null, and minor cosmetics.)

A taper deformer isn’t high-tech feeling and exciting, but it’s useful in everyday practice, and more to the point this is a structure that can be used for many useful kinds of deformations. For instance, once I had the taper structure it was pretty simple to replace the internal “taper” formula with one to do a twist:

I’ll share out the twist version eventually, in the meantime here’s the full taper compound (if you look inside you’ll see what I was getting at by the arbitrary axis adding a lot of seeming complexity, but it’s really not complex, ICE just tends to look that way when there are a lot of different things all connected.)

File (softimage 2013, 379kb): example_TaperDeform2

Categories : 3D Graphics, Examples
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I am a big fan of Polynoid. Ever since their first images of cybernetic snails came out I’ve been hooked on their often-dark blend of art-meets-tech imagery. 

Fabian Pross of Polynoid was, for a while, maintaining a very cool blog (come on Fabian, post new stuff!) One post in particular puts into words a critical concept I and many others often try to get across to newer artists – the importance of avoiding simulation where possible.

Simulations usually don’t quite achieve what you want them to, visually. The trap people fall into is to try to force a behavior out of a simulation. You end up making endless iterations while the setup you’re using grows more and more bloated and slow. A single directoral change becomes a nightmare. You lose control and the limitations of your setup starts to dictate the look.

The solution is to create what I think of as “deterministic” solutions – setups which change over time, but in very strict ways you specify. That’s one of the things I was trying to get at with the “post simulation” tutorials, the benefit of offloading much of the look outside of what is simulated.

Even skilled vfx artists fall into this trap with some regularity. I can’t say how many times I’ve seen production scenes which have grown bloated to the point of containing hundreds of forces and collision objects just to try to achieve a simple effect. You can’t afford it. A simple directoral change blows the whole thing apart. Stop. Take a deep breath. Don’t go over that cliff. Simulate judiciously, in small doses, only where you have to.

Simple simulation + deterministic stuff for a complex look = control.

And control is what makes a VFX artist, in my mind. Anyone can pull levers until they get a nice result out of fumeFX. But to achieve brilliant results which are new or spot-on to what is needed in prodution, you have to have control – be it in fumeFX, ICE, Realflow, Houdini or whatever. And one of the best ways to achieve control is to only simulate where you have to, and keep it simple when you do.

Fabian puts this idea into words better in this post. Even if the techniques he uses here are specific to ICE, the underlying message and workflow is the same everywhere – avoid simulation to gain control and speed.

Sparta

Even when you use simulation, who says that you have to stop there? Bake it and use it as an element you shape further or build on. This concept is really powerful. A good example of this idea in practice is demonstrated by a little DCC-agnostic tool called Sparta. Simulate, then shape the results.

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In the “postSim” tutorial we made shapes out of strands by constructing arrays of point positions. Many ICE users, myself included, forget that there are a bunch of shapes provided already which can be used in this fashion. They are in the “Debugging” section, because arrays like these can also be used with ICE attribute display properties to create onscreen widgets (hint: …or to add points to a pointCloud…)

I’ve found the factory nodes to be quite handy for a number of things, but I wanted some other shapes of my own (such as a star and spiral)  - so I made them, as well as made some adjustments to what was already available (with some digging) to suit my personal preferences. Here is a scene with a number of them, each packaged as a compound.

Freebies!

And here’s the file (softimage 2013 322kb): ICE Debug Elements

While experimenting around with these elements as display objects, I made a “protractor” compound.

It’s of limited production use because of a current problem with how softimage displays these elements in a shaded or hidden line view, and because it wasn’t particularly designed as a tool… it just evolved while I messed around. But it serves as an example of how you can use the “Debug” nodes to create visual feedback (another good example of these debug elements is the factory “bend” deformer in ICE.)

Judicious use of these display attributes can make a packaged compound much more useful, as well as act as a handy jumping off point to make interesting shapes with strands etc. Enjoy! – AM

File (softimage 2013 270kb): example_ICE_protractor

The spiral compound plus the postsim tutorial makes a nice basis for a “cloud chamber” like wallpaper… :)

Categories : 3D Graphics, Examples
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Jan
07

Example – PostSim Needles

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During the making of the film “Barnyard,” which happened to be around the time ICE was being first conceptualized and built, a number of effects were identified which were a challenge at the time. Some of those effects became some of the first demonstration compounds later, presumably Helge and others still had those challenges in mind… making footprints in mud, falling leaves, rain/snow interacting on characters etc.

One effect involved a bunch of hay getting dumped on a character. At the time Hans Payer completed the effect via some nice scripting and syflex tricks. Now in ICE it is pretty easy, so when a thread about a similar effect was mentioned on the softimage list, and so soon after I had done the post-sim tutorial, I gave it a quick go. They basically asked for a way to use strands with the “falling leaves” compound. Here’s the result… while the collisions are not accurate the way RBDs would be I hope it’s food for thought at least. :D

Caveat: like similar tricks using the post simulation tree, motion blur is a concern… this is the kind of “quickie” effect that can often get you by, but hero shots would take a lot more effort, for instance if you had to see clearly the fibers bend and react to collisions, collide with each other, accurate mb etc. That kind of difference in the details is why feature film effects can get so hairy – often you can’t get away with simple cheats like this one.

File: softimage 2013 .scn, 237 kb

example_postSimNeedles

 

Categories : 3D Graphics, Examples
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Jan
07

Example – More value propagation in ICE

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Same basic deal as the prior example, but much simpler and using a weightmap. In this case a turbulence pretty much drives the whole thing.

The main appeal is that it’s a ‘lil planet. Everybody loves lil planets, right?

File: softimage 2013 .scn ~190kb

example_propagateValueViaWeights

 

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Jan
06

Example – Greeble Push in ICE

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SI-Community has a “resource dump” for scraps of stuff people want to share in an unfinished or flawed state for others to pick over. This “Greeble push deformer” I made a while back is IMHO a good candidate for such a bin, so I’m sharing it there.

BTW, if you don’t regularly visit SI-Community, why not? It, rray.de and the softimage mailing list are the heart of the softimage community. And vimeo:

It works fine, so why am I putting it in a “public rubbish bin” rather than releasing it with fanfare? Well, I’m not particularly proud of it lol. Here are some reasons why this isn’t awesome:

  • It’s a “push” style deformer, meaning it doesn’t create geometry it just deforms it. That kinda blows, it means you have to start with a very dense mesh. In fact, this is the main reason why I haven’t released the loads of terrain stuff I’ve got hanging around – I haven’t come up with a good way to make the geometry as I go and add detail only where it’s needed that isn’t too slow.
  • This is just worley noise hooked to a push deform structure and a repeat node. I was sure a zillion people were going to do it, in fact I’m amazed I haven’t seen this compound done better from someone else. Surely we have some Star Wars fans somewhere messing with ice?
  • I never bothered to add in a control to decrease the amplitude of the noise per generation. This would be easy enough to sort out but I never got around to it.
  • The deformer respects normals, but the noise itself is spatial, in other words it doesn’t “flow” along the surface, which would be nice. Note the sphere shape in the video, instead of looking like the death star it reveals this spatial, circular character of the worley noise.

But it’s hardly doing any good sitting on my hard drive so here you go – consider it an example of how to iterate a push deformer. Try turbulence instead of worley noise and it will look a little terrain like. Change the worley noise and you can make some crater-like looks. So it sucks, but in a kinda fun way. Hope it’s of use to someone.

- AM

File: softimage 2013 scene, ~3 MB

example_worleyGreebleDeform

Categories : 3D Graphics, Examples
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To make a point that the underlying concepts introduced in this simple tutorial are far more important than the simple look of our example, here are some images which derive from the simple parametric circle equation discussed. The scene used to make the anaglyph is below. This isn’t rocket science stuff, this is novice level ICE… and much of it applies to realflow, thinking particles, maya or whatever. Cheers – AM

 

And here’s the scene used to make the anaglyph version, with comments throughout (softimage 2013 ed, ~200kb) spirographEmission_anaglyph

Categories : 3D Graphics, Examples
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So, we’ve made a strand circle which rings our original point positions from the simulation, now let’s make those circles align with the rotation of the simulated particle. In practice this is very, very simple. Just insert a “rotate vector” node after you calculate the coordinates on a circle for the strand points, and then use the particle orientation as the input rotation.

Ok, that was nice, but why did it work?

Point positions are vectors. Vectors are displacements:

This is one of the simple but critical concepts that is the real purpose for me writing this series of posts, because it’s a foundational way of thinking which lets you come up with solutions to problems every day.

What is a point? It’s a place, within a space. A particle can have all kinds of attributes, like color size and orientation. But a point is just a position, it only has a single value, a vector (x,y,z). In a manner of thinking, a point is a vector. The vector which describes a point is a direction and distance from the origin. It’s a displacement from that point of reference. When you talk about “global” and “local” space you are talking about different frames of reference, different points of origin from which to draw a vector describing points.

So, what we really did when we calculated an array of strand positions on a circle was make an array of vectors. Hence, rotating those vectors is really the same thing as rotating the strand point positions to match the orientation of our original particle. Points are vectors, they are offsets (or displacements) from an origin. And ICE is very, very good at doing stuff with points vectors. You can call these manipulations vector math if you want, but that in itself doesn’t make it beyond your average artist, who like ICE are also very, very good at manipulating points. If you are an artist you already have an intuitive grasp of vectors! You just need to define some terms, so that saying stuff like “rotate a vector” translates to the visual adjustments you do in your head day in and day out.

Seeing stars… and why modulo is so handy:

Ok, cool. We have a bunch of strand rings centered and oriented where our simulated particles were. Let’s make the rings star shapes, as a way of talking about another useful technique in ICE (it’s useful all over in fact), making patterns via the modulo function.

Ok, a digression first – some housekeeping. By now you’ve realized this isn’t one of those step-by-step makes-a-scene tutorial, I’m discussing more and glossing over a lot of the details you may need to actually plug all this together. I really should have provided a sample scene earlier, I don’t want you focusing on plugging nodes together, the whole point of this is the underlying ideas. So here you go. A sample scene with nifty comments and stuff. If all you want is a scene that will make circles and stars, there you go. And it was made with an educational license, even. But if you want the ideas used so you can make all kinds of other stuff, well then dear reader, read on.

The modulo function is just an instruction to divide two numbers and pick out the decimal remainder of that division. If you feed a linear sequence of numbers (like the index of an array: 0,1,2,3… call any of these numbers “n”) into the modulo function, you get a value counting up between 0 and 1. You can use this to identify every “n’th” item in your list. In fact if you crack open ICE’s “every n’th particle compound etc you will basically see exactly this.) If you can do things every “n’th” time, you can make patterns. Think about it. Braiding hair, knitting, drawing a dotted line – making almost any pattern involves counting and every “n’th” count doing something differently. Modulo is how you do that kind of thing in ICE (and elsewhere. Hey, realflow has an ICE like system now. And it works in scripting too. This math stuff pops up everywhere. The big secret is this – it’s just a way of looking at things you probably already do really well.

I’m a visual thinker so when I was first learning about modulo I had to scribble on a napkin, with results something like this:

All a star shape is, is a pattern where we take every other point on our circle and change it’s radius. Now we know how to find every other point from our list (the array) of strand positions, so we just change the radius of the formula we used to make the circle for those points. And you get a star.

Cooooool.

Ok, so just one last part to this tutorial, and a brief one – how to take the single circles we made and, using the earth-shaking power of ICE and the post-simulation region, turn that result into a lot of circles: all different and making little atom things like we see in the example video. And in fact, the example scene here already shows you how, so we’re not even going to do much besides discuss it and crack bad jokes. Cheers. – AM

The file (softimage 2013 educational, 1.2 mb)

strandPostSimOffset_tutorialPart4

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Andy Moorer

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