Large Scale Crowd Sims with Boids

Tutor Amit Official

This will be nice for creating zombie

I'm trying to figure out how to make this crowd of boids stay contained within a moving object. Could really use some advice on how to approach this. Nothing seems to be working. I'm using 2.93.2. I've tried parenting the emitter and the individual crowd elements to the moving container, which doesn't seem to help... as the container moves the crowd just falls off the end. I've done a bunch of searching and watched a bunch of boid tutorials with no luck.

Where do we download the crowd from

the emiter has a size setting you can change the scale and randomize scale

Quick question: how do I adjust the size of the people? I can make the emitter bigger, but the particles seem to remain the same size.

Ian Hubert

Oh thanks for sharing! I'm going to have to mess around with that! Do you still get problems if collision is turned off for the emitter object, and you just use a different object for the collusion/ground plane?

Erich Stenzel

Ah! Thanks for clueing me in!

Lukas Sprehn

I think he means that this is taking place before Dynamo, since it began with Axle in Shadow State Five.

VideoSlice

OK I figured it out. In 2.91 they interact naturally with the collision object if you turn off "allow land" so none of the default boid settings are turned on! Just an FYI to anyone trying this out. Spent easily two days of headache tweaking settings and assuming boids were broken~

VideoSlice

amazing tutorial! Just used this for a big ol' overhead shot of a biplane coming in for a landing at an airstrip. Just one more layer of realism to the piece! I realized too late that moving the source "people" or the collision plane seems to cause the particles to clip through your collision surface with no easy way to make them 'stop' at the collision again asid from rebuilding everything... appears to be a bug.

Goals can be very good for zombie crowds

This crowd is not covid friendly

Most people watching this: "ah yes, i can finally add convincing people to my city scene!" Me: "FuN CitY,"

Juan Romero

mmm, not sure about that, they could argue "the same functionality can be achieved with the new particle system" and there you go boids!!!!! I hope not but it has happended before.

Ian Hubert

Yeah I'm talking totally out of ignorance here, but I feel like the particle system hasn't been touched in a LONG time, and it's kept working as long as nobody touches it- but that's why they've been holding off for the current "everything node" project? We're getting a big ol' particle update with that, yeah?? I think? Oh man they better not take away my sweet baby boids.

Juan Romero

I just hate Blender particles can't be individually randomly offset in time. It shouldn't be that hard to do but once I poked some developer about it and it seemed to be like cold fusion to him, the universe could potentially implode.

Love your content man you're the best.

Erich Stenzel

Yay! The fate of Axle Rubix is finally revealed! (I like to think that was entirely for my benefit :-)) Thank you for these videos on Boids. I need to think of an excuse now to use them in a future project!

This takes me back to watching the LOTR special features dvds as a kid and seeing how they simulated the crowds with Massive (Which Weta made for the films I think?). I assume Massive is a more advanced piece of AI software than the particles in Blender, but it’s all making settings and introducing rules right? Is there a way for us in Blender to make an amount of the particles only follow some of the rules or have different settings? I’m imagining it could look even more realistic crowd if some of the people stood still in groups, while the others moved around them making their way to the goal. You could do it with two systems probably, but then the two systems wouldn’t interact and things would clip right?

cool as always Ian, thank youyou. are you going to do a day tutorial about post effects?

Doug Brown

Excellent... thanks Ian... some handy little pointers in this chat too. I can see me using this for a colony of ants... or a remake of Starship Troopers... :)

Ian Hubert

YES! I just found that out today! So nice- thanks for pointing that out. That's much easier than that whole "alphablend no shadow transparent material" song and dance :D

Jonathan

A bit unintuitive, but there's a separate "Viewport Display" section under the Particle Properties tab that has it's own "Show Emitter" checkbox. Unchecking that will hide the emitter plane without having to give it a transparent material.

Ian Hubert

HAH! I love it! 2008! I love that boids have been literally unchanged since, like, the 90s, too. Can't mess with perfection!

I remember playing with boids when I started with Blender. These are cool tips on how to use them usefully. Here's my 12 yr old boids video test by the way, lol: https://youtu.be/CAgTvMss1ZI

Ian Hubert

Oh no! Is it because I was covering ground too fast, or because I was starting with assets that you didn't have? Or because your laptop couldn't keep up? Cause I definitely want people to be able to follow along!

Ian Hubert

OH WHAT!?!? That's SUPER useful to know! I had no idea you could start physics type stuff before zero, thank you!

Regarding 16:20, In the particle settings, you can enter a negative number on "Frame Start" (say -50) so that you can skip the people falling from the sky part when you go back to frame 0.

I'm considering making a blender addon for this kind of thing that uses existing machine learning models for character-environment interaction (https://github.com/sebastianstarke/AI4Animation). I'll let you know how it goes :)

I usually try and follow along your tutorials on my laptop but today you've severely outdone me. congrats Ian, you've finally won, I hope you're happy.

Pete Burges

This is fantastic. As part of an episode or a movie, this shot reads like a genuine crowd- only the CG afficionados will suspect that it isn't, and slow it down or watch it on repeat to work out how it was achieved. And even then, it's a staggering achievement when you don't have a whole team of people with specced out workstations and a giant render farm at your disposal.

Ian Hubert

It's true, and I think that's one of the drawbacks of the boid system. ALTHOUGH- I wonder if, post-baking, it's possible to delete a specific particle? Cause yeah, if you had a sim that was pretty darn close except for one or two problem areas, it'd be GREAT to be able to just nix em.

Evan Barron

It would be very interesting to find a way to delete individual people who happen to be causing specific problems. Because the whole thing is one simulation, if one person is acting strange, you just have to figure out how to make the entire simulation better whereas finding a way to delete just the one person would be really helpful.

Ian Hubert

I agree! Doing that right now :D

that little bob in the step adds so much should definitely add it to them all

Love getting these long chunky videos to watch ngl, goes perfect with my dinner!

Ian Hubert

Oh man. If you're into people saying the word boid over and over and over- you're going to LOVE this video.

Mike Hay

Fantastic! I'm just moving into doing crowd scenes for an animated music video and this is SO helpful! Thanks Ian!

Shawn Hawkinson

Boid oh boid! Look at all those boid bois!

Ian Hubert

Hahaha, yeahhh- I keep thinking I'm done, then deciding to go back :P

Ian Hubert

You can absolutely make schools of fish with boids!!!!!

Kai Christensen

Yes! I SERIOULY need to try out boids, it really feels like there's a LOT of potential applications for this kind of logic-based simulation. OOH I BET YOU CAN MAKE SCHOOLS OF FISH WITH IT I'M GONNA TRY IT.

Oh so excited to watch this one!

damn still working on the waterworks shot

Jared Soto

Woohoo!