Lightwave Hellboy Fire Effect

ne of the best bits in superhero movies such

as Hellboy and the X-Men series is where

a character has the ability to cause fi re to

spew forth from their hands before hurling an

almighty fl aming ball at their nemeses. It’s certainly a handy

superpower, and we can only hope that these people are

sensible enough to ask someone else to fi ll their car up at the

petrol station. In this tutorial, we’ll show you the safe way to

recreate this fantastic ‘pyrokinetic’ effect.

Helping us with the drama is a lovely mademoiselle, who has

gleefully posed for a brief video clip, running down a deserted

corridor and screeching to a halt before summoning up her dark

powers and throwing a powerful blue thunderbolt – presumably at

someone who’s stolen her jar of Nutella. [Pardon? – Ed.]

The visual effects, of course, step in where our heroine’s powers

end: creating the fi reball and the wisps of blue fl ame that spring

from her palms as her power builds. We’ll use LightWave 3D to LightWave 3D to LightWave 3D

track a 3D model of a hand into the scene, which will then serve

as an emitter for particles that will lap around the hand and spiral

upwards. Volume HyperVoxels will enable us to render the particles

as an ethereal blue fl ame, and we’ll use After Effects to composite After Effects to composite After Effects

the render back into the background footage, enhancing it a little to

fi t the scene better.

Most of the actual work will be done with LightWave’s particle

tool, ParticleFX, and since we’ll be using collisions, calculating the

simulation will probably be quite slow and somewhat unstable. For

this reason, we strongly suggest saving the scene as my_scene_

v001.lws and using the Incremental Save feature to save a new

version every few minutes.

Benjamin Smith is Creative Director of Red Star Studio, a digital

fi lm production company. Sadly, his own superpowers are

limited to leaping tall kittens in a single bound.

www.redstarstudio.co.uk

O

060 | 3D WORLD3D WORLD February 2006

FACTFILE

FORLightWave 3D 8+

DIFFICULTYIntermediate / Expert

TIME TAKEN2-10 hours

ON THE CD• Full-size screenshots• Background footage• LightWave scene fi lesLightWave scene fi lesLightWave• Finished shot

ALSO REQUIREDA compositing program such as After Effects

Running into a dead end is no fun at all, so it helps if you have the power of LightWave 3D at your fi ngertips to blast a hole in the wall. We show you the best way to generate the necessary superheroic VFX BY BENJAMIN SMITH

Fire at your fi ngertipsLIGHTWAVE 3D

TUTORIALS | Pyrokinetic effects

February 2006 | 061

From the Compositing tab on the Effects panel, set the plate as the Background Image. In the Display panel [D], set the Camera View Background

to Background Image. Set the scene’s end frame to 320 and scrub the Time Slider to see our heroine go through her motions in the Camera view.

Set the Camera Zoom to something like 4.3 (roughly a horizontal fi eld of view of 35 degrees), and move it to about 1.5m in Y. Rotate it so the horizon and

perspective in the grid approximates that in the plate.

03

STAGE ONE | The background plate and initial scene

Locate the Fireball folder on this issue’s CD and copy it to your computer. Inside, you’ll fi nd a JPEG image sequence that makes up the background plate for

the shot, as well as a lo-res QuickTime movie. Load QuickTime movie. Load QuickTime LightWaveLayout, set the content folder to Fireball > lwcontent and, from the Image Editor, load the plate image sequence. Make sure the start frame is set to 1 and not 0.

01 02

Once you’ve got the position of the hand roughed out in 10-frame intervals, you can go back and fi ne-tune the position of the fi ngers to match the

live action. You can then start fi lling in keyframes where necessary between the 10s, so the 3D hand remains locked over the live action throughout the shot.

08

To create fi re fl ying from our model’s hand, we’ll need to rotoscope a 3D hand over her own and use it as an emitter for particles. Enter Modeler and load

hand.lwo from the Objects folder. This is a generic hand model with a simple skeleton already set up.

04Load hand.lwo into Layout, convert the bones layer to Skelegons and set the hand geometry to use these bones to deform. You can now move and

rotate the tiny root bone of the hierarchy to match the position of the model’s hand.

05Start at frame 220. Position the root bone over her wrist (you can see her watch, which is a useful guide) and rotate Bone01(7) to fl ex the hand into

position. You can roughly select and rotate the fi nger bones into position, too.

06

Step forward 10 frames and move the hand to keep it loosely in position. Repeat this at each 10-frame interval throughout the sequence, so the animation

is blocked out. The tricky bit comes around frames 250-280, where she pulls her hand back and shoots it forward. Make sure you move the hand back and forth in Z enough so that it scales with perspective.

07

STAGE TWO | Rotoscoping the 3D hand

▲Pyrokinetic effects | TUTORIALS

EXPERT TIPView the whole frameWith the 3D hand superimposed over our heroine’s own hand, it’s hard to see what she’s doing with her fi ngers. Refer to the background image by going into the Image Editor, making sure Use Layout Time is on and double-clicking the thumbnail image sequence. The current frame opens.

Since playback of the scene is jerky with the plate loading in the background, make a preview if you need to watch the animation back to check it. Alternatively, just load the fi reball_roto.lws scene from the CD to get to this stage.

i


With the hand nicely rotoscoped, you can start adding some particles. In Modeler, select the hand object, then copy and paste it twice into two other

layers. In the fi rst layer, delete the polygons around the wrist and use the Smooth Scale tool to expand the hand by about 3mm. Name the layer ‘Emit’.

09In the ParticleFX panel, the Nozzle should already be set to Object-Surface. Set the Birth Rate up to 500, the Particle Limit to 2,000, activate Fixed and

set the Start Frame to 180. Hit either the Calculate button on the Dynamics tab or bring up the FX Browser (Utilities > Plugins (Additional) > FX Browser) and choose Start.

11

Set the type to Object-Subdiv and Bounce/Bind power to 100. Simulate again and this smaller collision hand will repel the particles created just

outside its surface by the slightly bigger emitter hand, causing them to lap around the main hand. You can set Roughness in the Collision panel to 50% for variation.

14Once the fi re has started burning from the model’s hand, it shoots upwards and away. We want it to spiral in an organic, fl ame-like way, so we’ll add

a couple of Wind objects to propel the particles. However, we want these effects to be located around the middle of the hand.

15

The trail of particles looks great, but it should really drift upwards. Add a Dynamics Gravity object and simulate again to see the particles drift up. You can

add some randomisation by setting variations on Weight and Resistance with the +/– fi elds on the emitter’s Particle tab, as well as a tiny bit of Vibration on the Motion tab.

12

Shrink the second copy of the hand by a few millimetres and name this layer ‘Collision’. Both layers are automatically added to Layout, and you

just need to set them to use the bones from the Skelegons layer to animate them. From the hand_emit object’s Properties panel, add FX_Emitter on the Dynamics tab.

10

Add a null and call it parented_to_bone. On its Motion panel, add the Follower plug-in and set Item To Follow to be a suitable bone in the hand’s palm.

Turn on World Coordinates and turn off the HPB rotate and XYZ scale options (by setting Source to None). The null will now follow the position of the hand, but will remain oriented vertically (because it isn’t inheriting rotations).

16


Where particles are born under the hand, they now immediately pass through it upwards under ‘gravity’, so we won’t get any fi re lapping around it. To resolve

this, select the hand_collide layer. On its Properties panel’s Dynamics tab, apply FX Collision and open its panel.

13

STAGE THREE | Adding the particles

EXPERT TIPDon’t move!LightWave 3D 8.3 locks up the computer while simulating particles, so once you’ve pressed Start or Calculate, it’s important not to touch anything else in the program, or to try to switch to another application or process. This will crash LightWave, so resist the temptation to check your email! You can quit the particle simulation by pressing [Ctrl] for a few seconds if you really need to do something else. Thankfully, this bug has been fi xed in LightWave 8.5, which also has a handy progress slider for dynamics calculation on the FX Browser.

i

February 2006 3D WORLD 3D WORLD | 063

Pyrokinetic effects | TUTORIALS

Add a Wind, call it spiral_wind and parent it to the parented_to_bone null. Set the Wind mode to Rotation(Y), the Radius to 150mm and Spiral

Amount to 100%. Simulate and you’ll see the particles rise with a slight spiralling motion. You could turn this Wind off (tick the box next to FX_Wind in the Dynamic tab) to see the results of other Winds without being affected by this one.

17Add another Wind and call it turbulence_wind. Leave it at the origin and, on its panel, set Mode to Turbulence and turn off Falloff. Use the Vector

tab to set the Turbulence Size XYZ to 500mm and make Turbulence Vector X 1m. This Wind adds a random motion that helps to add more organic twists.

19

In the HyperVoxels panel, activate the hand_emitter layer, set Object Type to Volume and open VIPER to render a quick particle preview.

On the Geometry tab, set Particle Size to about 40mm and Variation to 50%. On the Shading tab, set Color to a suitable shade of blue, Opacity to 25% and Thickness to 5%. On the HyperTexture tab, choose the Crumple texture.

23You can use the Preview pop-up in VIPER to create a lo-res preview to check how the effect looks in motion. Particles tend to pop into and out of

existence, so you can use Gradients to control and refi ne the effect. Apply a Gradient on the Particle Size, set to Particle Age (so the particles are 0 per cent when they’re born), scale up really quickly and scale down as they get older.

24

We found that we had to turn the collision with hand_collide object off at certain points (like when the hand moves violently through the frame) to

prevent particles bouncing around like crazy. Add an envelope to the Bounce/Bind power, and keyframe it down to 0% if you experience any strange behaviour.

21Load particles_fi nal.lws to see the fi nal particle animation created for the shot. We applied a few more tweaks to add some extra detail and to fi x any

problems. We also animated the emitter’s Birth Rate so the fi re cuts off once the fi reball is released, and added a little random variation during the rest of the shot.

20

STAGE FOUR | Render settings for HyperVoxels

Add another Wind, call it vertical_wind and again parent it to parented_to_bone. Set this Wind’s mode to Cylinder-Explosion, its Radius to 250mm and

Power to –50%. Simulate and you’ll see that this Wind causes the particles to be sucked inward toward the middle of a cylindrical effector, so they seem to rise in a column without spreading out so much.

18

It may take some tweaking to get the HyperVoxels looking really good, and the render time for the sequence can be quite long. You can load the

fi reball_fi nished LightWave scene from the LightWave scene from the LightWave 3D World CD to 3D World CD to 3D Worldsee our fi nal settings..

25

We also created the actual fi reball, which is straightforward compared to the trail of fi re – a particle emitter simply shoots out of our character’s

hand at the appropriate moment, leaving a trail of particles that are rendered with HyperVoxels.

22

STAGE THREE (Continued) | Adding the particles

▲



The background video is extremely noisy (it was shot in low light), whereas the rendered fi re is totally clean. Add a Noise fi lter into the fi re effect

using its Alpha channel as a mask, and match the noise against our model’s dark surroundings.

29

As always with a composite, it’s the extra touches at the end that really help to sell the fi nal result. If you look at the fi nal_shot.mov on the CD, you’ll

notice that we’ve added a few extra sweeteners to this scene, such as the lens fl are that comes from the fi reball when it’s at its peak intensity. After Effects has a standard After Effects has a standard After EffectsPhotoshop-like lens fl are generator that works just fi ne, but

for this effect (pictured above), we used the excellent Knoll Lens Factory suite of plug-ins to make a really impressive Lens Factory suite of plug-ins to make a really impressive Lens Factoryfl are that sends refl ections across the shot. Alternatively, you could create this kind of effect by parenting a light to the fi reball emitter in LightWave, turning on Lens Flares to render it as a separate pass, and then compositing it in. All of these methods will produce a great fi nishing touch. ●

31

STAGE FIVE | Compositing in After Effects

We also added camera shake to the fi nal shot. Create a new composition and drag the fi rst composition into it. You can now expand the

motion options for the clip in the composition, scale it up a tiny bit and add keyframes for position and rotation to simulate shake.

30

In After Effects (or the compositing package of After Effects (or the compositing package of After Effectsyour choice), start a new composition at 640x480 (square pixels) and 25fps. Import the background

image sequence and the rendered fi re element, layering the render over the background (remember that the render only begins at frame 170).

26You can duplicate the fi re layer again and apply a Brightness/Contrast tool to darken it until only the brightest areas of the scene remain. Blur this and

layer over the original with the Blending mode set to Screen. This creates a highlight glow that seems to spill around the edges of the model’s fi ngers.

28Now copy and paste the fi re layer, select the lower layer and apply a Blur fi lter to it. Blur it by about 100 pixels until you have a vague blue blob, and

then set the Layer Blending mode to Screen. This will add a blue halo around the fi re, so it seems to light up the screen and nearby objects.

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Documents

Lightwave Hellboy Fire Effect