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View Full Version : Crowd Simulation, How?



drclare
11-24-2003, 02:44 AM
I know that in the manual, or on the box, or the website, it says that lightwave 7.5 can do crowd simulation. How do you do this, i heard that it works with the particle system? What i want to do is create an animation of a character, and i want that same animation duplicated a number of times, but somewhat random in position, rotation, and start time. So can i create this animation in a scene, and then link that scene to a particle emitter to get this effect?

Melvil
11-24-2003, 10:14 AM
I don't know much about it, but I think this tutorial (http://www.newtek.com/products/lightwave/tutorials/animation/flocking_birds/index.html) uses it.

-Dave

eblu
11-24-2003, 01:29 PM
I watched a tute on this at siggraph last year (through the newtek web streaming thing).
basically they built a character and gave him a walk/run cycle, and worked it up through motion mixer (something I have almost zero exp with bc of its bugs/flaws). then they emit a bunch of particles and have them ride over a surface, turn on the unique ID feature for the particles and then attach the character to the particles, that move the way they like. it looked easy... its not.

particles have serious problems, bc usually you don't want to render the "ramp up" portion of the particles, the part where particles are generating and may be off-camera. But if you don't render these frames, then the simulation screws up royally. Of course you can save the particle motion once you are happy with it (and if you are even thinking of network rendering, then You HAVE to save the particle motion to a file), but I have also had mixed results with That! I use particles sparingly, now.

I forget just how they got the cycle to apply to the character but it kinda animated with some ability to keep pace with the actual movement of the partical, but... it always looked cheezy, it never looked like the character was moving under its own volition. Even when the experts did it. For some things (like maybe "scooby doo") thats alright, but in my estimation, LW does Not do crowds well at all. maybe this will change in V8, but there are Too many holes in the features that LW relies upon to do it, for it to be worthwhile.
anyway, just my opinion.
-eb

monovich
11-24-2003, 05:00 PM
spent the last two months doing crowds in lightwave. In short, there is no easy way to do it, nor is there an elegant way, but it is possible to get some crowds.

Lightwave crashed all the time while doing it.

Our crowds ended up being stationary with very basic arms waving and dancing motion. We got away with it because the people were tiny and in a dimly lit environment.

-s

drclare
11-26-2003, 03:38 PM
If i have an object animated, but then parented to a null with the null also animated, can i use FX_Linker to copy the null onto particles and keep the object underneath it? Or will it just copy the null?

monovich
11-26-2003, 04:17 PM
it would just copy the null unfortunately.

there is a clone hierarcy LScript that will clone parented items, but you can't use it in conjunction with FX_Linker.

:(

Phil
11-27-2003, 09:42 AM
Presetcentral.com has an example called particleguy - I think that this is closely related to the one that most people have a vague memory of.

It helped here, but FX_Link is incredibly fussy. If you remove objects that are located earlier in the scene file, FX_Link will lose the connection to the PFX emitter(s). That's easy enough to fix (kill all linked objects and re-link them, but it's annoying and shouldn't happen at all. It's been reported to NT although I haven't had any comment back from them on this issue (have had on others though).

The annoying problem is that I haven't yet found a way to tie in the particle velocity to the endomorph. If your particle slows down, the endomorph just carries on chugging away. I'm not sure if there's any way to work this out - I just worked the shot slightly differently as time was running short.