Dot Physics

Modeling vs. Art

I have been reflecting on my recent failure to realize that the Giant Water Slide Jump was fake (more analysis here). I think the guys that made this video did a really good job on several levels. First, the motion appears to do two important things:

  • shows constant acceleration in the vertical direction
  • shows constant velocity in the horizontal direction

That seems like such a simple thing, but it is surprising how often fake videos don’t have those two elements. Maybe they were not close, but with the error associated with the panning and zooming camera, it seemed close enough. Also, to the credit of the makers of this video, they have a situation that is physically possible. So, I salute you Mr. Giant-Water-Slide-Jump-Video-Maker.

Here is the question. Should you use physical models to make animations or just ‘eyeball it’? I don’t think it should be model vs. art, because you can artistically use a model. Anyway, here are some cases:

The elephant jumping on a trampoline video. Here it is in case you missed it.

How would you make that elephant jump? In this case the creators seemed to have used mostly constant acceleration, but not quite. Maybe they wanted to the elephant to “hang at the top a little bit more” – you know, for dramatic effect.

Here is an analysis of a falling GPS unit from the movie Up. In this case, the motion is not based on physical models. I don’t know, it just seems like it would be easier to use constant acceleration than it would be to play around with it to get it to look “right”.

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And here is my favorite.

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In case you can’t tell, this is Sully from the movie Monsters Inc. Pixar had the problem of representing hair. Of course you could just find some way to ‘draw’ it, but you want it to look real. You know the way hair on a real blue monster would look. So, they came up with an algorithm for modeling hair and how it interacts with other hair around it. The result is realistic looking monster hair.

I am not sure this falls in the same category as the above situations because I would assume that Pixar would create a model that just works rather than use existing models that work in the real world. However, I think it is cool.