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QuaterNet: A Quaternion-Based Recurrent Model for Human Motion
- amelius 8y agoI was wondering about the advantage of quaternions over matrix/vector algebra, and found this quite interesting post: https://stackoverflow.com/questions/8919086/why-are-quaternions-used-for-rotations https://stackoverflow.com/questions/8919086/why-are-quaterni...
- notbob 8y agoRecurrent neural networks for modeling physical systems are starting to really come into their own. We have a few exciting years ahead of us.
- deleted 8y ago[deleted]
- babel_ 8y agoWait, so previous ones didn't consult the literature for animation systems and how (at least the ones I know) most of them nowadays use quaternions because of discontinuities and gotchas? That seems weird, even if you don't care about ik, quaternions have very nice properties for animation systems, and only add an extra variable (4 vs 3) so aren't too much of an overhead compared to reduced error handling or going all the way to 3x3 matrices.
- mikedh 8y agoI assumed that too until I read this slightly grouchy but very interesting thread: https://github.com/KhronosGroup/glTF/issues/1515 https://github.com/KhronosGroup/glTF/issues/1515
- miohtama 8y agoDid they in the end settle with quarternions as glTF is an export format (same playback on different apps) and not an authoring format?
- skocznymroczny 8y agoRotations in GLTF are specified with quaternions.
- throwaway66666 8y agoHa, sadly no! Whereas it's unacceptable for let's say an airplane to use euler, or a modern video game camera engine... Most animation software used by artists/animators uses euler angles, and in order to deal with gimbal lock they just... Use a 2 or even 3-child hierarchy (they call it "controllers") where each controller animates one axis (or two). That's a huge overhead compared to just using quaternions, but if it makes animators more productive it's probably worth it. Computer vs Human time. Especially in situations where render farms are used and a frame takes an hour to be rendered, does it really matter? ---- So, it's not the animation applications fault. it's the animators who always prefer euler + messy scene hierarchy :) I 've even see robotic arms be animated like that... robotic arms!