August 2008

Cartoon Explosion

Even though it’s just about impossible to find a Hollywood blockbuster these days that doesn’t include its fair share of special effects and explosions, people just don’t seem to ever grow tired of them. On the contrary; take a poorly written excuse for a story, add a couple of nice, rich explosions and some other FX while you’re at it, and people will still see it. Let’s not single out a specific film because there’s just too many to choose from. Nevertheless, in all fairness sake, the sheer fun of blowing things up just might vindicate an otherwise totally uncalled-for explosion, or possibly even a bunch of them.

Without getting to scientific, let’s have a quick look at what we are about to create. Everything explodes differently, so depending on what’s causing it the result can range from a massive eruption of fireballs to a modest puff. Even so, they do share the same elemental course of events. The abrupt and violent release of energy sets of the explosion from a small or limited area and will aggressively grow larger. As the explosion or cloud travels away from the point of origin it loses its energy and will settle down and gradually fade away.

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Hydraulic Piston in XSI

By looking at hydraulic pistons in action you’ll soon find there’s quite a lot things going on at the same time. When trying to recreate the same functionality in 3D, you’ll most likely become aware of it even sooner. As the arms, to which the piston is attached, moves the piston obviously needs to stay connected at both ends at all times. This is achieved by making it expand and contract. However, this will also change the rotation of the piston which is what makes the setup a bit complicated. While it is the hydraulic system that is driving the arm in reality, there’s really no point in creating the same setup in 3d since you’ll be animating by hand anyway. It’s far more intuitive to do it the other way around, animate the arm and make the piston follow the movement.

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Studio Lighting

There’s a certain irony involved when people enquire about photorealism because, apart from the spelling, there isn’t really anything ‘real’ about it. What we perceive as being ‘realistic’ in an image (or an animation, for that matter) has more to do with whether it’s consistent with our expectations of it, rather than whether it’s truly representative of the real world. Over time, we get used to certain motifs being rendered in a certain way, and any deviation from this stands the risk of being regarded as strange or unnatural. As an extreme example, imagine Godzilla painted in vibrant pink and yellow stripes. No matter how good the paint job is, or how cute he looks, the effect would still look slightly odd, to say the least.

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Stylized Fur Creation

Let me start of as a true party-pooper and point out that none of those characters where designed, modeled, covered in fur and rendered by a single person during a coffee brake (although while the final scene is rendering, you’ll probably have enough time for a good cup of java). Having given you that advice, please disregard it – because we’re going to try to do so anyway.

Given that carton or stylized animals generally are quite clear-cut and unfussy in there design, the time spent on adding fine details such as wrinkles and creases can usually be kept to a minimum. Basically, all you have to is to get a cube and start moving the points around till you’re happy with shape. Sounds simple enough, right? Well, even if the technical side of the modeling isn’t necessarily more complicated than so, it is the very same simplicity that makes it challenging. As you chuck out most of the details you stand a great risk of ending up with a rather meaningless and uninteresting character, which is pretty much the opposite of what you’ve original planed.

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Getting Started in Animation Part 1

While having the largest box of crayons in class may have been thrilling when you were a kid, ithad little or nothing to do with the quality of the images you drew. Although we doubt thatanyone would seriously argue with this, it’s something people often forget when it comes to 3D. With the manuals of modern 3D applications weighing more than the contents of a schoolsatchel, it’s as easy to be dazzled by the number of features available as it was by the number of crayons. But the basics of 3D are exactly that – basic enough for anyone to follow.

During this four-part tutorial series, we’ll introduce you to the fundamental concepts of 3D animation. While primarily aimed at newcomers, we also encourage more experienced users to drop by our 3D kindergarten; no matter how well you know your software, there’s no substitute to an understanding of the principles of weight and timing. At the end of the day, animation is all aboutbringing things to life, not marvelling at the tools employed to do so.

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Getting Started in Animation Part 2 and 3

One of many files lost when my old backup decided to crash, was all the images for the 2nd and 3rd part of the Getting Started in Animation. I should have a second backup somewhere tucked in the closet, so if anyone asks me to I’ll have another go at finding them.

In the meantime, both articles can still be found at 3D World’s website http://www.computerarts.co.uk/tutorials/premium_content/3d__and__animation/get_started_in_animation_part_2
and Getting Started in Animation part 3 at http://www.computerarts.co.uk/tutorials/premium_content/3d__and__animation/get_started_in_animation_3

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Getting Started in Animation Part 4

With the summer vacation just within your grasp, our 3d kindergarten are about to come to an end with this very issue. Throughout this four part tutorial series we’ve been focusing on the concept of animation, rather than fancy features offered by any given 3d software. With topics ranging from boxes of crayons to green peas we’ve surely had an odd mix of metaphors for the fundamental ideas, but this hopefully helped you getting the bigger picture.

During the course our hopper has evolved from just being a lifeless object to a joyful character with a will (and rig) of his own. Until now, we’ve put together the animation by directly moving and scaling the geometry of the hopper at different frames. While this approach is very straightforward and time efficient you don’t have any real control of the hoppers posture or any specific expression, even less the ability to change them over time. Using the rig from last issue enables us to continue working in the same manner as before, but with the power to add additional details to the poses and the animation as a whole.

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Realistic Grass

Step 1

Growing grass
From the Get > Primitive > Polygon Mesh menu chose Grid. Press [Ctrl] + [2] to switch to the Hair Toolbar. From the Create > Hair menu chose From Selection. In the Hair PPG, set the number of Total hairs 13000 or so. The lawn is still way to sparse, but using the Strand Multiplier will be more efficient than further increasing the Total hairs, so set it to 2. Next, set the Splay at tip to 0.5 and the Splay at root to 0.25 to separate the strands.

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Color at Vertices (CAV)

The short answer to the question is No. Well, if we are to be perfectly honest the elongated answer is sadly no as well. At least not in any sense that can be even remotely considered a 3d painting feature. With that being said, you do have some basic options to paint or store (color) information directly on your geometry. While they are limited at best, yet they just might do the trick if you’re not in the need of anything too fancy.

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Leaving Footprints in the Snow

Step 1
The snow surface
From the Get > Primitive > Polygon Mesh menu chose Grid. In the PPG set the U Length to 20, the V Length to 10 and change the U Subdivisions to 100 and the V to 50. Next, add a Randomize operator from the Modify > Deform menu. In the PPG, set the X,Y and Z Displacement 0.1 and the Repetitions to 15. From the Modify > Deform menu, chose Smooth. In the PPG, set the Strength to 5.

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