Adding noise/vibrations to a path animation?

[elder]

Hey Everyone,
I need a way to add noise/vibrations. I've got a path animation that's a fighter plane and it looks too computerized. I want to add some vibrations...noise to it. I'd even be willing to start my animation from scratch to insert the noise. I found a post where someone replied "One way to do it is to group an object to itself, animate the group, and make an expression for the actual object using the noise function:

object.tx = noise(time);
object.ty = noise(time);
object.tz = noise(time);

I guess the problem I have is where do you insert that information? Where is the noise function? I really feel dumb having to ask it but is there possibly a way someone could give me a step by step mini lesson from the "beginning to end" on the steps I need. Is this exactly the stuff I copy and paste somewhere and that's all?

I do modeling, texturing and lighting a lot but animation (and expressions) is somewhat new to me and would really appreciate someone's help. Thanks in advance.
Mark

[joojaa]

Okay, here goes idea first. Add a additional transform under the objects hiearchy, So just group it (even if its allready grouped make a ADDITIONAL group). Then bind the lowest level transfrom (the newly generated group), to the path anim. And put the expression to the child node. Now they sum up nicely.

DISCLAIMER:I had vey bad luck explaining this to a person who had little knowlege of how maya works. Because he had trouble selecting a group that parentted his object , so IF it seems it doesent work then, use a locator instead as a parent. A locator is the same thing as a group wich is just a transform without a shape (wich supprise supprise makes a group invisible also possibly confusing, if one desent know tha basics).

save your scene out just in case

Assign the expression to whatever object you want to path animate. (Its easier if the objects pivot is actualy located at 0 0 0 for step 4).

Group the object (yes it will be a group without any other objects) by hitting controll-g (make sure you dnt have capslock on) , Make sure that your group stays selected so dont select anything extra (or click around)!

(Conditional), if your object desent reside pivot at the origing, then its time to move the bnewly made groups pivot to wherever you want it by hitting insert and moving it where it should be, hit insert to exit.

if you yove come this far without selecting or deselcting anything then all should be okay, otherwise go back to your saved scene, begin from the beggining!

Shift select the curve.

Choose Animation menuset -> animate -> Motion paths -> Attach to motion path.
[/list]

[elder]

Thank you much! I appreciate it. I'm going to try it right now.

Also if anyone is also needing help in this area I thought I'd copy this info that I got in an email from Sean on the board.

---

Here's an example,

If I have a sphere that I want attached to a motion path, but I want the animation to be a little "noisy", I would put the sphere into a group of it's own and attach the group to the path, not the sphere itself. That way I can create the expression you're asking about on the sphere directly. If the sphere itself was attached to the path, you could not animate it by hand or with expressions, as you have probably noticed.

So, once the sphere's group, "group1", is attached to the motion path and the path animation is all how you like it, you could animate the sphere object any way you want, because the group that contains the sphere is constrained to the path, not the sphere object itself. You could animate the sphere by hand so that it moves around slightly within its group, which is moving along the path, or you could add an expression to do the animation for you, which is what I was referring to.

To create the expression, select the sphere (not the group this time). go Window -> Animation Editors -> Expression Editor... The Expression editor will appear, and the sphere will be listed under "Selection". This is just so that the object you have selected is listed with all of its available attributes which you could use in the expression you are about to write. In this example, the object selected is a nurbs sphere, and it is called, "nurbsSphere1". In the big box under "Expression:" you will type the following:

nurbsSphere1.translateX = noise(time);
nurbsSphere1.translateY = noise(time);
nurbsSphere1.translateZ = noise(time);

and click the "Create" button at the bottom. That's it, you have an expression. If you play the animation, you may notice that the ball moves more erratically along the curve, although probably not all that much.

The expression you made does the following: the nurbsSphere.translateX equals a noise function which is driven by time, and the same for translate Y & Z. It is easy to adjust the expression to increase the amplitude of the noise, or the frequency of the noise. To edit the expression open the expression editor, and under "Select Filter", click "By Expression Name". The "Objects" menu will list the expression you made, "expression1", and the expression itself will be listed in the box below. If you wanted to increase the amplitude of the noise, you might edit the expression to something like this, where the noise function is multiplied by four (or whatever you want):

nurbsSphere1.translateX = 4 * noise(time);
nurbsSphere1.translateY = 4 * noise(time);
nurbsSphere1.translateZ = 4 * noise(time);

When you're done editing the expression, click "Edit" at the bottom, and you're done.

If the noise is too slow or fast, you could multiply "time" in the noise function by any value as well:

nurbsSphere1.translateX = 4 * noise(time * 5);
nurbsSphere1.translateY = 4 * noise(time * 5);
nurbsSphere1.translateZ = 4 * noise(time * 5);

If you find that the noise expression is making the sphere move erratically in all directions, but you really only want the noise to be perpendicular to the path, you could just cut out the whole "translateZ" line (or whichever one(s) you don't want.

That's about it, hope it helps.

-Sean