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The Exhaustive Lightning Tutorial- Check back for revisions!

Posted: Wed, 23rd Jul 2008, 2:13am

Post 1 of 7

The Duelist

Force: 1289 | Joined: 10th Aug 2006 | Posts: 100

VisionLab User FXpreset Maker MacOS User

Gold Member

Rating: +9

The Exhaustive Lightning Tutorial

With the release of the new version of VisionLab, FxHomers around the world leapt up in joy- VisionLab finally had lightning! However lightning, unlike lightsabers, lensflares, and other appearance-based effects, is far more difficult to create accurately because of one thing that absolutely must be done right: the motion. Colors and glows are easy. Motion is what makes lightning act like lightning. It’s complicated, it’s scientifically amazing, and it’s very hard to do right. And that’s why I’m writing this tutorial; everyone should be able to create convincing lightning using Visonlab’s fine toolset.

To begin, let’s talk about the different types of cinematic lightning. There are two: weather and fantasy. Each are very different from each other, so much so that I’ve divided this tutorial into two sections, leading us into:

Weather Lightning

In this section, we’re going to learn how to make convincing lightning. First, let’s take the simplest: Cloud-to-ground. This is a very thrilling type of lightning to include in any storm, but how is it done? In a real storm, opposite charges build up in the clouds and the ground. Around a half-second before the strike, a leader -a faint column of hot, almost-plasma gases- jumps simultaneously from the cloud and the ground, meeting in the middle. The lightning bolt then surges down the leader anywhere from once to twenty times (the additional strikes called “return strikes”), creating the classic flicker that defines lightning. When I started research to become a better user of the lightning engine, I found that YouTube is the greatest resource one could have. I started looking at clips of lightning and jotting down what made it lightning. Here are a few clips that were instrumental in my understanding of a convincing effect.

http://www.youtube.com/v/JRJl70ACBBI

Notice how it flickers several times, then fades somewhat slowly away. Also notice that the acutal bolt is only visible for a short time. The flash obscures it for most of the clip. That’s something we’ll be taking into account later on.

http://www.youtube.com/v/bNhY3Hx83fA

In this video we can see movement of the branches. They stay one way for a bit, then when the next flicker comes along they shift, then flicker and shift again, going through some pretty wild contortions that last around a frame or two each. Remember that it’s these small things that look almost silly that actually sell the effect because they’re shown for such a short time. If you try to make your lightning look too picturesque and perfect, it won’t look real in motion.

Now, let’s get to actually creating it. I’ll be working in progressive just so the frame rate is simple. If you’re working in interlaced, simply double the time values. (Make the effect and the motions last twice as long). Here’s a sample clip of a lightning strike I made on Visionlab. We’re really going to pick it apart, so watch carefully. I’m going to use timecode if referring to a video I’ve posted here, and simply count frames from the start of the simulated effect.



There are four parts to this strike. 1: Bolt Layer 1. 2: Bolt Layer 2. 3: Flash Gradient. 4: Lensflare. Here are the current settings:




The bolt is keyframed to take four frames to complete the strike. On frame one, Grow: End is 0. On frame four, Grow: End is 100. The bolt then vanishes on frame five, by reducing the Start Width and End Width to 0. REMEMBER: It is EXTREMELY important to set “continuity keyframes” a keyframe inserted by the keyframe tool under the settings you are going to modify one frame BEFORE the frame that you are going to change. Otherwise everything will happen gradually, tweened from the last time that attribute was modified. That will WRECK the effect- lightning is very sudden and random. So on frame four, I’ve set a keyframe under the Start Width and End Width attributes, then on frame five I’ve set them to zero, causing the bolt to vanish.



You can download the Real Lightning Bolt presets to see the rest of the keyframes in detail, but basically after the first strike is done at frame five, I change the seed so that after two blank frames, the return strike looks a little different, then change it again and turn it on and off for several frames to create the flicker look. For the final seven frames, I set the Start width at 4.67 and the end width at 3.74 and tween them down to zero. I also (though this is optional) tween the glow down to fade along with the bolt, like in the first clip.

Well, now you’ve got the motion of a cloud-to-ground bolt down, so I’ll talk briefly about the glow. The important thing to remember is that lightning is generally not bright, chroma anything, blue being the exception. When it’s reddish or purple, I’d recommend setting it at the chroma-bright level and then under grade, tone it down through use of the saturation slider to match your footage in saturation. Lightning at night is generally more colorful than lightning during the day, which is generally almost white. If you need more inspiration for lightning color, go to Youtube and watch some more lightning videos.

In-cloud lightning is very similar in settings and technical aspect to cloud-ground. For in-cloud, I’d recommend using multiple trunks (but no more than three) with a fairly high start and end radius, and a fairly high angle range for the branches. Then follow the “strike, change and flicker” routine. Interactive lighting on the cloud helps enhance the effect. For any lightning, I’d use a diffuse grade with an inverted mask at the point where the lightning enters or exits the cloud. It makes it look as though it dives into or out of the cloud rather than jumping off of the outside.




The Flash: interactive lighting is very important with lightning, if not only to light up the set, but to do what lightning does on camera: blots everything out! Refer to the first clip, at around 0:37 in the slo-mo section it blots out the entire sky. That’s important in creating a convincing effect. I wouldn’t want to make you go to the trouble of masking the trees and applying light spill and such, so we’re going to use a one-flash-fits-all. There’s only really two things it needs to be. Number one is big and bright. This has to make the lightning shine with a fury, so it’s going to be composite: add, and LARGE! Number two is indistinct and fuzzy. It’s very important that it doesn’t look like a simulated lensflare. A high Gaussian blur and not too many hard shapes will help this. Keyframe the flash to be very bright on the large flashes and less bright on the weaker. On the end fade, start it bright and tween it down to zero. You can download the preset for this, it’s the Real Lightning Flash. A small lensflare on the target (in this case a tree) also helps lend a more dramatic effect to the strike.
Hope this helps create convincing weather-based lightning!

Magic/Force Based Lightning

Possibly the moment you’ve all been waiting for, here is how to create force lightning. Since there are no actual force-lightning users on hand, we’re going to refer to the next best thing: telsa coils.

http://www.youtube.com/v/FY-AS13fl30

Notice in this video the movement of the sparks when they hit something as opposed to when flying free. That’s something we’re going to use later.

http://www.youtube.com/v/iO7j5LKmd3I

This video is especially important. It shows how a spark behaves when it connects to something. And here’s the big thing: it doesn’t move very fast. On the lightning engine, I’d say a speed of no more than 6.54, progressive. Double it if you’re on interlaced.

http://www.youtube.com/v/zDFuUgXWHIw

Finally, the holy grail of all force lightning resources. Look at 5:00 to 5:15. This is EXACTLY what we are trying to do, albeit with a little more control.

Once again, a little science on how force lightning would be done. When a Sith or sorcerer uses Force lightning, they use their powers to create an imbalance of charge between them and the person or thing they’re zapping. Because Force lightning is more like a Tesla coil, it has a continuous imbalance in charge, with each bolt correcting the imbalance only for a fraction of a second. That’s why a coherent stream is rare and unrealistic, because the imbalance would be corrected, the bolt would stop, a new imbalance would be formed, and another strike would take place, over and over and over, producing the flickering, zapping effect.
Now let’s get technical. Here’s the sample clip that I made using the Realistic Force Lightning preset.



I apologize for the quality of the video; I grabbed the first camera I could find and went out without costume or anything. I’ll post a better clip as soon as I have the time, but for now, please focus only on the lightning.

To begin, have your character hold his/her arms out in front of him/her. Straight or almost straight elbows are best, because the place where the lightning comes out has to be the closest to the target, otherwise the charge would select another, less desirable pathway. Secondly, people for some reason love to splay their fingers out like spiders (and it looks more realistic with fingers rather than palms) so that only one of them is actually pointing at the target. Keep them more or less pointing in the same direction. I also like to use small lensflares on the point where the lightning comes out so I don’t have to worry too much about finger alignment. No lensflare and intensive rotoscoping doesn’t look any better than a lensflare with less rotoscoping.

A moment before the actual lightning comes out, a subtle flicker of electricity around the hands as the lensflare is tweened in over around ten frames really gives the effect a unique “charging” look. Refer to the tesla coil clips, copying the dim and random zapping that occurs when a bolt hits nothing but air. After ten or so frames (longer if you desire a more emphasized charge), start your main lightning effect. You can check out the stats of the preset, Realistic Force Lightning, but I’ll give an overview of the important parts here:

Destination: No matter what your target is, slight to severe changes in destination make the effect convincing. If your target’s a person or other wide object, the places the lightning strikes should move around as the seed changes. I’d also recommend multiple points of impact (which necessitate separate effects, not just multiple trunks)

Speed: If you're going for the true 'tesla' look, no more than 6.54 on deinterlaced or progressive footage! If you're going for the Emperor's look, set the speed to 30-35.
Start Width and End Width: Keep them roughly equal, maybe a couple points higher on start, however remember the Tesla coil videos; the bolts that actually make connection are about the same width at start and end.

Seed: Remember to set continuity keyframes that will keep your seed constant until the frame that you want to change it. Changes need to be sudden and often. But how often? This is what I call the ‘tick.’ On a tesla coil, the power affects the speed of change. For instance, you could have a steady tick. tick. tick. tick, the branches changing maybe twice per second, or you could have tick-tick-tick-tick four times a second, or a speedy tickticktickticktick, possibly 16 times a second. The question is, what tick speed is the best? Well, for strong, powerful lightning in large amounts, I’d recommend changing both the seed and the destination every two to five frames. (For classic Emperor, change the destination every 5-6 frames. For slower, meandering lightning, five to eight. For an unbroken connection of one bolt connecting, say two wands, I wouldn’t change the seed or destination, but occasionally have the bolt vanish and the subtle flicker mentioned above appear for four frames, then immediately go back to the bolt. The speed of the bolt in this case could be a little faster, but no more than 15. Look at this video for a closeup of the flicker:

http://www.youtube.com/v/ZWbVDn19bIM

Look at this one for the whole shebang, but skip the geek talk to 7:41.

http://www.youtube.com/v/sQDcE4my9zw

See how it connects, dances, disconnects, flickers and then re-connects? That’s the look you’d want.

Now, back to the speed of the changes. I’d keep them fairly constant, but variation adds randomness that looks very good on the finished effect. Just don’t let anything linger too long. It’s far better to err on the side of quick changes than leave a bolt in the same place for too long.

Trunks: Varying the number of trunks for short periods looks great and behaves like real lightning. Just don’t go overboard.

Branches: The thicker the lightning, the fewer the branches. Thicker lightning means a better connection, so less streamers would go off into the air. Telsa coils typically have thick bolts, but force lightning is thinner, so take that into account.

Sticky: Makes the branches act as though they’re attracted to something. Only turn it on for a streak of lightning running down someone’s body or sinking into a surface. Normal Sith-to-victim bolts don’t need it.

Sticky Jitter: Thank God Sticky doesn’t actually need to be on to use this. This makes the branches switch around periodically and is a great tool! Set it at 100 for normal force lightning.

Glow: I like to layer two copies on top of each other and make a silvery inner glow with a wide, deep blue background glow.

Scatter Strength: I personally think Force lightning doesn’t benefit from scatter the way weather lightning does, but it’s a matter of personal taste. I leave it at zero for Force lightning.

Interaction with the person and the environment also is very important. Parts of Force lightning will zip off into the air, or hit the ground or a nearby object. Occasionally, it will briefly lose connection and go back to the hand flicker for a couple frames. The person or object being hit doesn’t actually need a ton of lighting flowing over their surface, because (as described in the Chriss Angel video) an electric shock kills you by going through your body and generally out your foot. Keep surface travelers short and sparse, using sticky if you like the effect.

Another thing to do is have small bolts leap off of the object or person and leap either into the air, a nearby object, or the ground. If it’s a person being hit, and their feet are in the shot, have periodic flickers of energy around their shoes. That’s the lightning going to ground, and in the Chriss Angel video you can see it when he gets injured, the lightning goes out his foot and into the ground.

Lastly, the force lightning flash is similar to the weather lightning flash. I keep it only for really big hits, but that’s a matter of personal preference. You can use it as much or little as you want and the effect will still be convincing.

As for sparks and smoke, a light smoke raising off your target is good, if it looks subtle and realistic. A person who’s been hit by force lightning doesn’t look like a chimney. Sparks are okay if you can rig a good particle effect to do what you want, or find some good stock footage. I’d keep them quick, and once again, subtle. You don’t want to distract from the lightning, and large showers of sparks are unrealistic.

Well, I hope you’ve enjoyed this tutorial. I’ve done my utmost to ensure every aspect was covered, but if there’s anything more I can do, or any questions you’d like answered, don’t hesitate to say so. Also, this is my first tutorial, so please let me know if I've helped at all!

-The Duelist.

Last edited Mon, 1st Sep 2008, 6:48am; edited 6 times in total.

Posted: Wed, 23rd Jul 2008, 3:55am

Post 2 of 7

Mandalorian

Force: 1905 | Joined: 24th Feb 2006 | Posts: 266

VisionLab User VideoWrap User Windows User

Gold Member

Very nice for a first tutorial. Lots of information to think about. I think this will be very beneficial to everyone. Thanks for taking the time to make this tutorial, I really enjoyed it. biggrin
Posted: Wed, 23rd Jul 2008, 8:19am

Post 3 of 7

Simon K Jones

Force: 27955 | Joined: 1st Jan 2002 | Posts: 11683

VisionLab User VideoWrap User PhotoKey 5 Pro User MuzzlePlug User PowerPlug User PhotoKey 3 Plug-in User FXhome Movie Maker FXpreset Maker Windows User

FXhome Team Member

Very cool tutorial! Could do with a few more gaps between paragraphs, just to make it easier to read, but otherwise great stuff. +1 and a news post.
Posted: Wed, 23rd Jul 2008, 3:49pm

Post 4 of 7

The Duelist

Force: 1289 | Joined: 10th Aug 2006 | Posts: 100

VisionLab User FXpreset Maker MacOS User

Gold Member

Wow! A news post? I'm so glad I could be of help here! I'll add a few of those line breaks, though, you're right about that.
Posted: Thu, 24th Jul 2008, 8:15am

Post 5 of 7

JackPot

Force: 10109 | Joined: 3rd Oct 2005 | Posts: 384

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Gold Member

Wow nice work on the tutorial! Its great to see the engine being used effectively!

The lightning strike you have created looked particularly great. The preset will be a must have for all fxhomers!

I have managed some other types of effects with the engine:

http://jack.fxhome.com/movies/Plasma/
http://jack.fxhome.com/movies/Orb/
http://jack.fxhome.com/movies/Flubber/
http://jack.fxhome.com/movies/Cells/

Although its designed for lightning you can create some other wierd effects, although I am not sure how useful they are biggrin
Posted: Thu, 24th Jul 2008, 6:01pm

Post 6 of 7

The Duelist

Force: 1289 | Joined: 10th Aug 2006 | Posts: 100

VisionLab User FXpreset Maker MacOS User

Gold Member

Thanks, JackPot! Interesting effects on your part. I never thought of something like that before, so your turn to write a tutorial! The blood plasma one was particularly nice, looked like something out of CSI. It seems the lightning engine is rivaled in complexity only by the particle engine, so I'm not surprised at its versatility. I think the lightning engine is the best FxHome product to date! ...But then again, I'm a lightning aficionado. I've loved any kind of lightning since I was four and saw the Emperor's mighty display.
Posted: Fri, 25th Jul 2008, 1:53pm

Post 7 of 7

The Flying Fox

Force: 1316 | Joined: 1st Sep 2007 | Posts: 155

VisionLab User FXpreset Maker FXhome Movie Maker Windows User

Gold Member

Fantastic Tutorial, really in depth and improves understanding of the concept, which is what you really need from a Tutorial. +1.