rotation by number

[Master chief]

OK i recently posted a post with a test of a helicopters main roter , now i have been testing some spin speeds and have gotten mixed results , apparently the blades need to spin The right way or every one dies. my questions is that in order to get some of the good spin speeds i have to rotate 4000+ degrees a second and that number is getting pretty big like 12000+ 8-9 minutes into the animation, i heard a while back there was a way to make a item rotate X amount of time by using some pose option but the only ones i could find where on of or 0-100% . any one know how to do this?

[rusty]

OK i recently posted a post with a test of a helicopters main roter , now i have been testing some spin speeds and have gotten mixed results , apparently the blades need to spin The right way or every one dies. my questions is that in order to get some of the good spin speeds i have to rotate 4000+ degrees a second and that number is getting pretty big like 12000+ 8-9 minutes into the animation, i heard a while back there was a way to make a item rotate X amount of time by using some pose option but the only ones i could find where on of or 0-100% . any one know how to do this?

 

I saw a tut many years ago which showed how to rotate an object where you just entered the number of spins... as I recall the rotation handle was rotated instead of the bone. Unfortunately I own almost every tutorial cd/DVD made for A:M and I've not been able to find it again. Hopefully someone will know and answer you and we'll both find out.

 

Beyond that I'm not at all certain that actually spinning the rotor is the best way to go. I don' do cartoons, only realistic and personally I would create a disk with a decal with outline of the blades going all around it and an alpha channel making the rest invisible. Then I'd make the outline of 4 of the blades even spaced around the disk darker and then I'd rotate the disk slowly, a little faster when it goes faster and when it goes real fast I'd rotate it back wards slowly.

 

Just my 2 cents.

 

Rusty

[John Bigboote]

Sounds like between you and Rusty you have the answer...

 

MC- You know how to switch from quaternion to euler rotation math, right?

[Rodney]

I'm with Rusty on this.

Whether in cartoon or realistically it may be better to lathe a disk or decal a patch and represent the spinning of the props that way versus actually rotating the blades.

 

One of the reasons this tends to be a better solution is that rotating objects tend to create a false sense of turning due to their symmetry. This is best demonstrated with the example of a character walking past a fence where all the fence planks are exactly the same. The lack of difference in the planks (or helicopter blades) can give the illusion that nothing has moved as the sequence plays.

 

Having said that there are approaches to this that can work with actual spinning. Those renderings can even be used to get the nice images you'd need to 'cheat' the effect.

 

I did notice that almost one year ago to this date the answer to your question was answered. I'm not sure you got a chance to read the responses then as you were more interested in the orientation of the blades. Looks like everyone anticipated your question by approximately one year. Check it out and see if this doesn't lead you to the solutions you are looking for. I see about four different approaches here and there, Euler Rotation, Expressions, MUFOOF and imagery.

 

Regarding the strobing phenomenon:

One of the issues we face when rendering a spin in 3D is that the images will be rendered onto a 2D plane; the screen. Something that looks like its rotating in 3D space may not convey the same movement within that plane. In some cases the rotation may appear to reverse or (something to avoid) not rotate at all. This is fairly easy to address with objects that we can change to create differences and avoid symmetry. In the fence example we might remove a fence plank or tilt one or two in a different direction. This is harder to do with objects such as rotor blades which have an expectation of being the same.

 

Regarding Euler Rotations.

This was my approach when I created my first rotor animation. Simple math will get it done and its almost as straightfoward as entering the number of rotations; 1, 2, 3 and so on. Just enter the numbers in increments of 360; a full rotation.

 

360=1 rotation

720=2 rotations

1080=3 rotations

etc.

 

If you need to rotate in increments of a full rotation (to make sure the spin looks right to the viewer) you can work in thirds/halves etc.:

 

480= 1 1/3 rotation

540=1 1/2 rotation

etc.

 

Here's your previous 'Rotor Fix' topic which may already have the solution you need.

[Master chief]

um yes i have switched it to eular , my problem is that the rotation number is like 14890 and im starting to lose the correct count

[Rodney]

um yes i have switched it to eular , my problem is that the rotation number is like 14890 and im starting to lose the correct count

 

You might want to do the rotation in an Action. Actions excel at cyclic motion.

Then you could specify how many rotations by number (1, 2, 3 ...559) in the Action's properties once assigned to the Model in the Choreography.

 

So the idea would be to divide and conquer.

 

In this way you could develop different rotations and swap them out in as needed.

 

Do you know how many rotations you need?

[Rodney]

Here's a quick project that demonstrates the idea.

I set it to 400 rotations in 1 second and I think it just laughed at me.

Looks more like 10 rotations.

 

It would be helpful to know more about your goal here.

 

now i have been testing some spin speeds and have gotten mixed results , apparently the blades need to spin The right way or every one dies. my questions is that in order to get some of the good spin speeds i have to rotate 4000+ degrees a second and that number is getting pretty big like 12000+ 8-9 minutes into the animation

 

I think MUFOOF is the only thing that will keep us from attending the funeral.

I'll miss everyone.

 

8-9 minutes into the animation

 

Is there a particular reason this 9 minute shot needs to be contained in one choreography?

spinspinspin1.zip

spinspinspin1.mov

spinspinspin.mov