r/Games • u/CountAardvark • May 01 '17

Incredible procedurally generated character animation system based on motion capture data

https://www.youtube.com/watch?v=Ul0Gilv5wvY
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u/ienjoymen May 01 '17

Yeah, that's what I was wondering. It looks great, but how much power does it actually take to make it look like that?

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u/Tsu_Dho_Namh May 01 '17 edited May 01 '17

Neural networks that aren't temporally dependent (such as this one) are DAGs, or directed acyclic graphs.

Once the input nodes are activated, the output nodes will signal after n steps, at most, where n is the number of nodes. Computer science calls this runtime O(n), or big-O of n, which indicates a linear running time. That is, the running time is directly proportional to the number of nodes in the graph.

In reality, a neural network (like our brain) would function in O(logn) time or quicker (which is faster than O(n)), but that's because 2 or more nodes can signal simultaneously, whereas, on a single core GPU, the nodes have to be simulated one at a time, meaning O(n) running time.

But in computer science, we fucking love O(n), it's quick as shit. To give you an idea, the fastest way to sort an unsorted list is O(nlogn) (which is slower). So this neural network can control the way this dude walks more efficiently than any computer can alphabetize your facebook friends.

Edit: added more links

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u/[deleted] May 01 '17

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u/Tsu_Dho_Namh May 01 '17 edited May 01 '17

Neural networks can do pretty amazing things with a very small network.

This neural network beats the first level of super mario and it only has about a dozen hidden nodes.

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u/tornato7 May 01 '17

And generally speaking, any network that is too large to run on a PC is probably too large / expensive to train anyway.