Hi There,
I was playing around with the new rigging features in version 16.
Quite nice.

I was rigging a horse. I have animations like trot, gallop etc correctly rigged and animated,
But i was wondering if any Houdini user ever found a procedural way to make the horse go forward at the correct speed.

(in a way that would make it possible to blend between trot and gallop after 40 meters for example)

Anybody ever did something similar by any chance?
And I was wondering if you know any kind of mathematics or method to calculate the speed of a horse moving forward in a animation? (most run cycles that I see are on a single spot) I have always been guessing the speed of the horse moving forward unless there might be a better way to calculate?

Da Costa

Moin,

> But i was wondering if any Houdini user ever found a procedural way to make the horse go forward at the correct speed.

I am not sure that I fully get what you mean by “go forward at the correct speed”. Horses don't just speed up their motion vectors when “going faster”, they will usually make wider steps. So if your basic animation is laid out well (*NOT* motion captured or if so, then tweaked and edited so that you can refine it), you can, to some degree, lengthen the steps but *may* have to change the overall timing (not a good method for “game accuracy”, i.e. you want to stay within, say, 24 frames).

> (in a way that would make it possible to blend between trot and gallop after 40 meters for example)

You would need the passing phase from trot to gallop, it's not a simple change “this frame = trot”, “this frame = gallop”. Again, as long as you are not talking about game optics.

> Anybody ever did something similar by any chance?

Yes, and it is not trivial.

> And I was wondering if you know any kind of mathematics or method to calculate the speed of a horse moving forward in a animation?

Just take the touch down moment in your animation (foot hits ground) and measure the distance covered until lift off. You can do that even with animations that run “in place”, since the hoof will still move the distance within local space of the animation. Together with the fps rate of your animation you basically have the speed the horse is moving at.

Marc

I did this once, although not in Houdini but Softimage, maybe the few insights I have about this will be of some value to you.
From my experience if you intend to use the animated character into something other than to showcase your animating walk/run cycles skills, or a game, you'll want to not animate “in place”. The way I did it, was to move forward the hips ctrl and keep the global (main parent of the rig) in place. Then, when the cycle end at the n'th frame, snap the global ctrl by the amount the hip moved forward. You can save all the animated ctrls in action clips (not sure what's the term in H, something related to CHOPs I'm sure) which can be cycled indefinitely and work only the global ctrl. Of course, this is relatively simple when dealing with a forward movement, which is rarely the case in movies/commercials and then you'll want to bake to editable keys every “captured” animation for full manual control. The (more costly, but with better results) alternative is to use motion capture, something you're probably aware of.

This is the animation I was talking about:
I also did a trot and a single suspension gallop animation where I used the technique I described above (not in the video since it's a short walk), but those never met the public eye since they've been abandoned before were unfinished. Now that I've managed to get the animation itch I'll have to scratch and I might get back to them to finish what I've started, a decade ago.