Help Request: 3d shape on an animated spline, and lightning

Hello - I've looked for tutorials and through the forum, and my search-fu is weak right now.

I know how to make a 2d animated light wave (think lightsaber, but more like a whip) effect follow a keyframed motion path, but I really want to figure out how to make one in 3d so that depth effects like perspective can be easily added.

I have created a cylinder shape in a 3d scene, but I want to make the shape follow an animated path through the scene, and that's what I can't figure out.

If anyone has any advice, I would greatly appreciate it.

The effect I'm going for is like the image below, where the tip of the saber looks bigger since it is closer to the camera perspective.

Thank you!

And the lightning question is: Does anyone know how to procedurally make a lighting effect in 3d space? I've found tutorials on making them in 2d, but nothing for 3d.

Thank you!

So are you trying to create a 3D lightsaber?
Because if you're after something else, it may be better to show the stuff you're working on yourself, because then the suggestions will align with your needs. A cylinder animated in 3D space is quite different from whip like motions. Without for example the Krokodove plugins it's pretty difficult to create animated 3D lines in Fusion. But let's start at the beginning: what is it that you really need?

I'm looking to create a light whip - same principal as a lightsaber, but along an animated, flexible path. See the image below.

So far all I have is a cylinder shape in my scene - if I can figure out how to animate a cylinder along a path, I can figure the rest out.

What is the plugin you referenced?

There is a Saber plugin made by Video Copilot for After Effects that does what I'm looking for (animate a glow along an animated path) but it is also just 2d - I'm just looking for a way to do it animated in 3d space.

Any other suggestions?

For that sort of thing to look good with a 3d approach, you probably need an actual physics simulation for the spline. You'd have to track the camera in 3D, and object track the handle of the whip, then attach the spline to the base of the handle, run the physics sim, and adjust the properties of the spline, like stiffness, mass, drag, gravity, etc, so that it doesn't flop around like a wet noodle. Houdini 18's added tools to help guide simulation, but I'm not sure if they'd apply here, I'm new to it. Once the physics was behaving properly, you'd give the whip geometry, and decide whether or not to texture it in 3D space, or do that in the 2D composite. If the whip is a completely CG element, you'll also need to rotoscope out anything that passes in front of it, such as your actor.

It might be easier, and give you more natural results if you used a real prop, and altered its appearance in post. That'd pose its own problems, though. You'd need to use a small shutter angle and high framerate to be able to minimize the motion blur of the whip enough to track and/or key it, then add motion blur back to the scene to keep it from looking Saving Private Ryan-y.

I wouldn't worry so much about it being "real" 3d just so that you can do depth of field and motion blur. You'll need to match the amount of DOF and MB to your actual footage anyway, and it'd probably be faster to render and give you more control if you kept that part of the 2D composite.

Anyway, this sort of effect is a high-budget Hollywood feature, type thing. It's not the sort of thing you just download a plugin, and press a button to do. It's not beyond the purview of a single, talented artist, but I think a VFX boutique might have a few people working on it, if only to split off the rotoscoping, I mean, if we're talking lots of shots.

And the lightning question is: Does anyone know how to procedurally make a lighting effect in 3d space? I've found tutorials on making them in 2d, but nothing for 3d.

Thank you!

The lights in Fusion are technically 3d, and technically procedural, but Fusion's renderer can't cast area shadows, or do global illumination, and its ambient occlusion is limited to SSAO. If you want the light of the whip to interact with elements of the scene (ie, cast shadows, illuminate objects), you'd need to render that in a dedicated 3d package, and composite it with Fusion.

Houdini is great for procedural. There's a free learning edition, and a cheap indie version after you've learned enough to want to get rid of the watermarks. It supports more advanced render engines if you ever want to move to those. Ideally, BMD would add support for them in the future.

Camera tracking and scene reconstruction are other elements of the puzzle that you might need to consider, though. I use C4D for that, and it works in a pinch, but Syntheyes, PFTrack, and Boujou used to be the standards for that. I'm not so sure what the kids use these days.

**edit**
OH, you said lightNing. There's a Reactor plugin by Vito from Pirates of Confusion AKA Captain LeBuck. The plugin is called blitz something.

Oh, and one last thing. The saber plugin from videocopilot is just a frontend for glows, displacement, and distortion. There's nothing in it that you can't do with Fusion. That's all the easy stuff. The hard stuff is getting the glowing, displaced, distorted bits to interact with your live footage.

Here's a little thing I did a while back that uses a lot of the same techniques. I didn't use a real fluid dynamics sim, and only used 2d tracking on her hands, but the glows and the turbulence, compositing, etc are all native Fusion.

It might be easier, and give you more natural results if you used a real prop, and altered its appearance in post. That'd pose its own problems, though. You'd need to use a small shutter angle and high framerate to be able to minimize the motion blur of the whip enough to track and/or key it, then add motion blur back to the scene to keep it from looking Saving Private Ryan-y.

A practical whip is all but impossible to direct effectively and safely unless you have a very skilled user. We did some whip shots for Teen Wolf a couple years ago in which the actor just had the handle and we added a CG whip. It was all hand animated, though—the client wanted to art direct the behavior too much to make simulating useful.

The Krokodove plug-in suite does have a tool that might be useful. It's called Tube3D. However, Krokodove is available only for Fusion Studio (not the free version).

The easiest way to obtain Krokodove (sometimes abbreviated KKD) is to download it from Reactor.

Capture.JPG (229.15 KiB) Viewed 1511 times

A practical whip is all but impossible to direct effectively and safely unless you have a very skilled user.

I just fell down a very deep, very dark YouTube rabbit hole, trying to find an example of the old 80's practical effect where they'd film the tentacles coming off, then play it back in reverse. I almost didn't resurface with anything besides Cthulhu nightmares for my troubles... until I found...

... some very helpful reference footage:

^^^ It's the Smarter Every Day guy and a bull whip expert with a Vicon mocap rig at 500fps. No, really.

Now that is some cool stuff! Thanks! It's got me curious about modeling that motion in Houdini. Might be a fun little project to learn more about dynamics.

Off the top of my head, there was an episode of Buffy the Vampire Slayer where they did the reverse tentacle gag with vines. I believe the technique was discussed in the audio commentary on the DVD. Season 4, episode 18 "Where the Wild Things Are."

So, I tried a physics-based approach, and... it's interesting...

I can see where the main problem isn't getting the sim to work accurately. Rather, it's what happens when you do. Not only do you need to be a good animator, but you also need to be good at using a whip!

I *think* I got my virtual whip to crack once because when I did, all of the constraints utterly exploded.

It's definitely a fun experiment though, and it was a good softbody dynamics learning exercise. Here's my setup. I only have a few months of experience with it, so I welcome suggestions from more experienced users and would caution other beginners against following my lead. It's Houdini 18 Indie, but should work in Apprentice (I think). Since this is a Fusion forum, I'll also post an .FBX and .EXR once I get a halfway decent animation and have some time to cook out a frame.

https://drive.google.com/file/d/1BkUCD3OMA196rw0UixVdsRDNL8WOhonG/view?usp=sharing

screenshot

Screen Shot 2020-09-04 at 1843.jpg (76.22 KiB) Viewed 1396 times